The Dragon Archive - User contributions [en]

RACE Computer Expansion Cage

2021-06-12T09:20:18Z

Maestrosoftware: Got confirmation (from tjewell) that reading address $feff does switch to slot 2

This is a cartridge port replicator by [[RACE Electronics]], pretty much like the [http://www.cocopedia.com/wiki/index.php/Multi-Pak Tandy CoCo MultiPak], that allows up to 4 cartridges to be inserted.

==Technical information==
* Writing to address $feff will select one of the 4 slots (0-3 - only bits 0 and 1 are used ; other bits are discarded).
* Reading address $feff will select slot 2

== Pictures ==
<gallery>
Image:RACE_Expansion01.JPG
Image:RACE_Expansion02.JPG
Image:RACE_Expansion03.JPG
Image:RACE_Expansion04.JPG
Image:RACE_Expansion05.JPG
Image:RACE_Expansion06.JPG
Image:RACE_Expansion07.JPG
Image:Race-cart-front.jpg
Image:Race-cart-back.jpg
Image:Race-cage-front.jpg
Image:Race-cage-back.jpg
</gallery>

[[Category:Hardware]]

RACE Computer Expansion Cage

2021-06-03T17:38:48Z

Maestrosoftware:

This is a cartridge port replicator by [[RACE Electronics]], pretty much like the [http://www.cocopedia.com/wiki/index.php/Multi-Pak Tandy CoCo MultiPak], that allows up to 4 cartridges to be inserted.

==Technical information==
* Writing to address $feff will select one of the 4 slots (0-3 - only bits 0 and 1 are used ; other bits are discarded).
* Reading address $feff will select slot 2 (to be confirmed on other boards)

== Pictures ==
<gallery>
Image:RACE_Expansion01.JPG
Image:RACE_Expansion02.JPG
Image:RACE_Expansion03.JPG
Image:RACE_Expansion04.JPG
Image:RACE_Expansion05.JPG
Image:RACE_Expansion06.JPG
Image:RACE_Expansion07.JPG
Image:Race-cart-front.jpg
Image:Race-cart-back.jpg
Image:Race-cage-front.jpg
Image:Race-cage-back.jpg
</gallery>

[[Category:Hardware]]

Memory Map

2021-06-03T17:37:23Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FEFF
| [[RACE Computer Expansion Cage]]
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40-FF44 (?)
| [[Delta DOS]]
| (from a quick disassembly of Delta DOS ROM)
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF49
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D CMD_REG Command/Result ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_LATCH_REG - single byte parameters ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_READ_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_WRITE_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF54
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_STATUS_REG AVR status ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF55
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_PIA_MAP PIA redirect (write only) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF56
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D_RAM_CTRL RAM / ROM control register ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_MSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF59
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_LSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF59
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF5A-FF5B
| [[DragonMMC SDCard|DragonMMC]]
| RAM bank read / write registers ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF69
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF79
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-31T13:38:02Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */ Added DragonMMC info from forum

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40-FF44 (?)
| [[Delta DOS]]
| (from a quick disassembly of Delta DOS ROM)
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF49
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D CMD_REG Command/Result ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_LATCH_REG - single byte parameters ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_READ_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_WRITE_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF54
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_STATUS_REG AVR status ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF55
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_PIA_MAP PIA redirect (write only) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF56
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D_RAM_CTRL RAM / ROM control register ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_MSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF59
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_LSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF59
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF5A-FF5B
| [[DragonMMC SDCard|DragonMMC]]
| RAM bank read / write registers ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF69
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF79
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-31T13:34:40Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40-FF44 (?)
| [[Delta DOS]]
| (from a quick disassembly of Delta DOS ROM)
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF49
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D CMD_REG Command/Result ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_LATCH_REG - single byte parameters ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_READ_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_WRITE_DATA_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
-
| FF54
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_STATUS_REG AVR status ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
-
| FF55
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC D_PIA_MAP PIA redirect (write only) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
-
| FF56
| [[DragonMMC SDCard|DragonMMC]]
| Dragon D_RAM_CTRL RAM / ROM control register ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
-
| FF58
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_MSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
-
| FF59
| [[DragonMMC SDCard|DragonMMC]]
| D_SAMBITS_LSB (16 bits as programmed to SAM) ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF59
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF5A-FF5B
| [[DragonMMC SDCard|DragonMMC]]
| RAM bank read / write registers ( [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938])
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF69
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF79
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-29T21:43:28Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */ added coco Miniflash (info from forum)

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40-FF44 (?)
| [[Delta DOS]]
| (from a quick disassembly of Delta DOS ROM)
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF49
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF59
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF69
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF79
| [http://www.cloud9tech.com/ Cloud-9] Coco miniFlash
| Flash bank selection register (selectable between FF49, FF59, FF69, FF79) [https://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&t=10938]
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T22:06:21Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40-FF44 (?)
| [[Delta DOS]]
| (from a quick disassembly of Delta DOS ROM)
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:58:10Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control register ([https://archive.worldofdragon.org/phpBB3/download/file.php?id=4675])
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:56:06Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|-
| FFE0
| Compusense [[Dragon Plus]]
| 6845 control registerban
|
|-
| FFE1
| Compusense [[Dragon Plus]]
| 6845 data register
|
|-
| FFE2
| Compusense [[Dragon Plus]]
| Memory bank register & status of 6845 display
|
* Bits 1-2 : select 32K bank (00 = standard lower 32K ; 01= bank A ; 11 = bank B)
* Read bit 0 : 0=video display available (i.e. blanking) / 1=video display not available (not blanking)
* Write bit 0: 1=select video RAM in the lower 2K
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection

|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:38:39Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]] - default addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate addresses
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:38:08Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF8F
| [[The Dragon's Claw]]
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FF9F
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFBF
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:37:30Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF80-FF9F
| [[The Dragon's Claw]]
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-FFAF
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFBF
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFB0-FFCF
| [[The Dragon's Claw]] - alternate address
| Rockwell 6522 VIA - 16 registers, base address can be changed to FF90, FFA0 or FFB0 with a wire link
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:29:48Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04-FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:29:07Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5F
| [[Touchmaster Tablet]]
| PIA ( [http://archive.worldofdragon.org/index.php?title=File:Touchmaster_UserGuide_09.jpg])
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T21:25:43Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42-FF43
| [[Dragon Speech Synthesis|JCB Microsystems' Dragon Speech Synthesis]]
| PIA data and control registers ([https://archive.worldofdragon.org/browse/downloads/Software/Dragon/J.C.B%20Microsystems/Dragon%2032%20Speech%20Synthesis/JCB%20Speech%20Synthesis%20Module%20User%20Manual.pdf])

|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:53:47Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Command/status register
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Track register
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| Sector register
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| Floppy data register
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Talk:Memory Map

2021-05-28T20:23:07Z

Maestrosoftware: Created page with "=FF56 for DragonMMC= In Simon's first version of this page, it said that FF56 was used by DragonMMC. I can't find a reference to that address in DragonMMC's dragon assembler s..."

=FF56 for DragonMMC=
In Simon's first version of this page, it said that FF56 was used by DragonMMC. I can't find a reference to that address in DragonMMC's dragon assembler source code... but I might not have looked thoroughly.

Memory Map

2021-05-28T20:22:16Z

Maestrosoftware:

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:19:26Z

Maestrosoftware:

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196)
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:13:06Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register [https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48< [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF57
| Dragon-MSX2+ (in MPI mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+ (in MPI mode)
| V9958 ports
|
|-
| FF5C-FF5D
| Dragon-MSX2+ (in MPI mode)
| YM2149 ports
|
|-
| FF5E
| Dragon-MSX2+ (in MPI mode)
| Video select port
| Only bit 0
|-
| FF76-FF77
| Dragon-MSX2+ (in native mode)
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF78-FF7B
| Dragon-MSX2+ (in native mode)
| V9958 ports
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7C-FF7D
| Dragon-MSX2+ (in native mode)
| YM2149 ports
|
|-
| FF7E
| Dragon-MSX2+ (in native mode)
| Video select port
| Only bit 0
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:10:38Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register [https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48< [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF57
| Dragon-MSX2+
| YM2413 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF58-FF5B
| Dragon-MSX2+
| V9958 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF5C-FF5D
| Dragon-MSX2+
| YM2149 ports ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
|
|-
| FF5E
| Dragon-MSX2+
| Video select port ([http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906])
| Only bit 0
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:08:21Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register [https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48< [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40-FF43 (mirrored upto FF5F)
| Voltmace Delta 14B multi-button joystick adapter
| 6821 PIA [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF4A
| CocoSDC
| Flash Data Register
|
|-
| FF4A
| CocoSDC
| Flash Control Register
|
|-
| FF4C-FF4F (mirrors once at FF5C-FF5F)
| Ikon Drive
| [http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=9&p=23906#p23906]
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T20:03:19Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register [https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48< [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: command register (write), status register (read) [http://archive.worldofdragon.org/phpBB3/download/file.php?id=2248]
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 1
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
| For CocoSDC: param register 2 or data register 1
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
| For CocoSDC: param register 3 or data register 2
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:57:16Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==
{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register [https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48< [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller - HDDATA - data transfer byte (read/write)
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: read HDSTAT status, write HDRSET reset
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDATTN ; get attention of controller
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| MFM disk controller: write HDMASK ; controller dma and interrupts (not used on coco or dragon)
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59 )
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:45:44Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Comments and references
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
| PIA 0 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48, [http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf] p.196 )
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| PIA 0 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| PIA 0 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| PIA 0 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| PIA 1 side A data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| PIA 1 side A control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| PIA 1 side B data register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| PIA 1 side B control register ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf] p.48)
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
| Disk controller latch
|
|-
| FF50
| [https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf Burke & Burke Coco-XT]
| HDDATA - data transfer byte
|
|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC CMD_REG ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Latch ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Read data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| Dragon MMC Write data reg ( [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm], [https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm])
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| MPI (and clones) slot selection ([https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf], p.59
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|-
| FFA0-FFAF
| MooH
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:37:02Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
|
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Burke & Burke Coco-XT
| https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/CoCo%20XT%20Hard%20Disk%20Interface%20v2.4%20(Burke%20&%20Burke).pdf
| HDDATA - data transfer byte
|

|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:34:34Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40-FF5F
| [[Dragon I/O Cartridge (Rink)]]
|
| To control which output pins are high and which are low, you write a single byte to any address between 0xFF40 and 0xFF5F.
|
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:31:49Z

Maestrosoftware:

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| [[DragonMMC SDCard|DragonMMC]]
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| | [[DragonMMC SDCard|DragonMMC]] ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:30:20Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| Dragon MMC ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7A-FF7B
| Orchestra 90
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:28:30Z

Maestrosoftware: /* DIY PROJECTS */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| Dragon MMC ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF79
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Orchestra 90
|
|
|
|-
| FF7B
| Dragon-MSX2+
|
|
|
|-
| FF7B
| Orchestra 90
|
|
|
|-
| FF7C-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:28:16Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| Dragon MMC ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF79
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Orchestra 90
|
|
|
|-
| FF7B
| Dragon-MSX2+
|
|
|
|-
| FF7B
| Orchestra 90
|
|
|
|-
| FF7C-FF7E
| Dragon-MSX2+
|
|
|
|-
| FF7F
|
* MPI
* Mega-Mini MPI
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf, p.59
| MPI (and clones) slot selection
|
* Bits 5-4: # of active CTS slot (ROM)
* Bits 1-0: # of active SCS slot (Floppy Disk Controller)
|-
| FF90-91
| MooH
|
|
|
|-
| FFA0-FFAF
| MooH
|
|
|
|-
| FFC0-FFD9
| All Dragons
| SAM Control bits (see below)
|
|
|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:24:29Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| Dragon MMC ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|
|-
| FF76-FF79
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Dragon-MSX2+
|
|
|
|-
| FF7A
| Orchestra 90
|
|
|
|-
| FF7B
| Dragon-MSX2+
|
|
|
|-
| FF7B
| Orchestra 90
|
|
|

|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:23:00Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|
|-
| FF56
| Dragon MMC ???
|
| Dragon MMC ???
|
|-
| FF56-FF5E
| Dragon-MSX2+
|
|
|

|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:21:50Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FFEF
| [[RACE Computer Expansion Cage]]
| Paper manual
| TO BE CONFIRMED
| Bits 0-1 : slot selection
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC CMD_REG
|
|-
| FF51
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Latch
|
|-
| FF52
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Read data reg
|
|-
| FF53
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| Dragon MMC Write data reg
|

|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:18:25Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|-
| FF50
| Dragon MMC
| https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm , https://github.com/prime6809/DragonMMC/blob/master/DragonFirmware/defs/mmc2def.asm
| CMD_REG
|
|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:10:12Z

Maestrosoftware: /* DISK CONTROLLERS */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|}

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:09:28Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24-FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port
|-
| FF2C-FF2F
| Dragon Alpha
|
|
| Dragon Alpha Floppy Disk Controller
|-
| FF40
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF41
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF42
|
* Dragon FDC
* Coco FDC
* CocoSDC
* Becker Port (DriveWire)
|
|
|
|-
| FF43
|
* Dragon FDC
* Coco FDC
* CocoSDC
|
|
|
|-
| FF48
|
* Dragon FDC
* Coco FDC
|
| Disk controller latch
|
|}

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:05:09Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF25
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF26
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port

|}

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T19:04:11Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Addr
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF20
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A data register
|
* Bit 0 - cassette data input
* Bit 1 - RS232 data output
* Bits 2-7 : 6 bit D/A(.25 to 4.75 volts out)
|-
| FF21
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side A control register
|
* Bit 0 - control of CD : 0=FIRQ to CPU disabled, 1=enabled
* Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
* Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
* Bit 3 - Cass Motor control, 0=off, 1=on
* Bit 4,5 - always 1
* Bit 6 - not used
* Bit 7 - CD interrupt flag
|-
| FF22
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B data register
|
* Bit 0 - RS 232 data input
* Bit 1 - single bit cound output
* Bit 2 - RAM size input
* Bit 3 - VDG Control Output CSS(color set ct)
* Bit 4 - VDG Control Output GM0&NOT(INT)/EXT
* Bit 5 - VDG Cont Output GM1
* Bit 6 - VDG Cont Output GM2
* Bit 7 - VDG Cont Output NOT(A)/G
|-
| FF23
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 1 side B control register
|
* Bit 0 - control of cartridge, 0=FIRQ to CPU disabled, 1= enabled
* Bit 1 - Interrupt input, 0=sets flag on falling edge of cartridge, 1=sets flag on rising edge of cartridge
* Bit 2 - Normally 1, 0=changes FF22 to DDReg
* Bit 3 - 6 bit sound enable
* Bits 4,5 - always 1
* Bit 6 - not used
* Bit 7 - cartridge interrupt flag
|-
| FF24
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF25
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF26
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF27
| Dragon Alpha
|
|
| Dragon Alpha PIA
|-
| FF28
| Dragon Alpha
|
|
| Dragon Alpha 6850 Modem Port

|}

<pre>
65316 FF24 - Dragon Alpha PIA
FF25 - Dragon Alpha PIA
FF26 - Dragon Alpha PIA
FF27 - Dragon Alpha PIA
FF28 - Dragon Alpha 6850 Modem Port

</pre>

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T18:51:02Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Hex
! scope="col"| Decimal
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
| 65280
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
| 65281
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
| 65282
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
| 65283
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
| 65284
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
| 65285
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
| 65286
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
| 65287
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|

|}

<pre>

65312 FF20 Bit 0 - cassette data input
1 - RS232 data output
2/7 - 6 bit D/A(.25 to 4.75 volts out)
65313 FF21 Bit 0 - control of CD
0=FIRQ to CPU disabled, 1=enabled
Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
Bit 3 - Cass Motor control, 0=off, 1=on
4 - always 1
5 - always 1
6 - not used
7 - CD interrupt flag
65314 FF22 Bit 0 - RS 232 data input
1 - single bit cound output
2 - RAM size input
3 - VDG Control Output CSS(color set ct)
4 - VDG Control Output GM0&NOT(INT)/EXT
5 - VDG Cont Output GM1
6 - VDG Cont Output GM2
7 - VDG Cont Output NOT(A)/G
65315 FF23 (Coco) POKE 54 to disable auto exec of cartridge
POKE 55 to enable auto execute of cartridge
Not certain re above for Dragon
Bit 0 - control of cartridge
0=FIRQ to CPU disabled, 1= enabled
Bit 1 - Interrupt input
0=sets flag on falling edge of cartridge
1=sets flag on rising edge of cartridge
Bit 2 - Normally 1, 0=changes FF22 to DDReg
3 - 6 bit sound enable
4 - always 1
5 - always 1
6 - not used
7 - Cartridge Interrupt Flag
65316 FF24 - Dragon Alpha PIA
FF25 - Dragon Alpha PIA
FF26 - Dragon Alpha PIA
FF27 - Dragon Alpha PIA
FF28 - Dragon Alpha 6850 Modem Port

</pre>

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T18:50:17Z

Maestrosoftware: /* INPUT/OUTPUT ADDRESSES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

{| class="wikitable"
|-
! scope="col"| Hex
! scope="col"| Decimal
! scope="col"| Device
! scope="col"| Reference
! scope="col"| Comments
! scope="col"| Bit by bit
|-
| FF00
| 65280
|
* Dragon 32
* Dragon 64
|
* https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
* http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf - p. 196
| PIA 0 side A data register
|
* Bit 0 right joystick button
* Bit 1 left joystick button
* Bits 0 to 6 Keyboard row input
* Bit 7 joystick comparator input
|-
| FF01
| 65281
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side A control register
|
|-
| FF02
| 65282
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B data register
| Bits 0 to 7: keyboard column output
|-
| FF03
| 65283
|
* Dragon 32
* Dragon 64
| https://www.lomont.org/software/misc/coco/Lomont_CoCoHardware.pdf - p.48
| PIA 0 side B control register
|
|-
| FF04
| 65284
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF05
| 65285
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF06
| 65286
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|
|-
| FF07
| 65287
|
* Dragon 64
* Dragon Alpha
|
| ACIA
|

|}

<pre>
65280 FF00 Bits 0 to 6 Keyboard row input
Bit 7 joystick comparator input
FF01 PIA
65282 FF02 Bits 0 to 7 keyboard column output
FF03 PIA
FF04 ACIA - D64/Alpha
FF05 ACIA - D64/Alpha
FF06 ACIA - D64/Alpha
FF07 ACIA - D64/Alpha

65312 FF20 Bit 0 - cassette data input
1 - RS232 data output
2/7 - 6 bit D/A(.25 to 4.75 volts out)
65313 FF21 Bit 0 - control of CD
0=FIRQ to CPU disabled, 1=enabled
Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
Bit 3 - Cass Motor control, 0=off, 1=on
4 - always 1
5 - always 1
6 - not used
7 - CD interrupt flag
65314 FF22 Bit 0 - RS 232 data input
1 - single bit cound output
2 - RAM size input
3 - VDG Control Output CSS(color set ct)
4 - VDG Control Output GM0&NOT(INT)/EXT
5 - VDG Cont Output GM1
6 - VDG Cont Output GM2
7 - VDG Cont Output NOT(A)/G
65315 FF23 (Coco) POKE 54 to disable auto exec of cartridge
POKE 55 to enable auto execute of cartridge
Not certain re above for Dragon
Bit 0 - control of cartridge
0=FIRQ to CPU disabled, 1= enabled
Bit 1 - Interrupt input
0=sets flag on falling edge of cartridge
1=sets flag on rising edge of cartridge
Bit 2 - Normally 1, 0=changes FF22 to DDReg
3 - 6 bit sound enable
4 - always 1
5 - always 1
6 - not used
7 - Cartridge Interrupt Flag
65316 FF24 - Dragon Alpha PIA
FF25 - Dragon Alpha PIA
FF26 - Dragon Alpha PIA
FF27 - Dragon Alpha PIA
FF28 - Dragon Alpha 6850 Modem Port

</pre>

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+
FF7F - Mega-Mini MPI | DOSPlus Extended

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>

Memory Map

2021-05-28T18:15:57Z

Maestrosoftware: /* INPUT/OUTPUT ROUTINES */

== MEMORY MAP ==

DRAGON 32 and 64 in 32 mode

<pre> 0 - 1023 0000 - 03FF SYSTEM USE
1024 - 1535 0400 - 05FF TEXT SCREEN
1536 - 3071 0600 - 0BFF GRAPHICS: PAGE 1
3072 - 4607 0C00 - 11FF PAGE 2
4608 - 6143 1200 - 17FF PAGE 3
6144 - 7679 1800 - 1DFF PAGE 4
7680 - 9215 1E00 - 23FF PAGE 5
9216 - 10751 2400 - 29FF PAGE 6
10752 - 12287 2A00 - 2FFF PAGE 7
12288 - 13823 3000 - 35FF PAGE 8
13824 - 32767 3600 - 7FFF PROGRAM USE
32768 - 49151 8000 - BFFF BASIC ROM
49152 - 65279 C000 - FEFF CARTRIDGE USE
65280 - 65535 FF00 - FFFF INPUT/OUTPUT
</pre>

PLEASE NOTE:
With disks in use, the Disk work space occupies the first
page of graphics (1536 to 3071) and in consequence Graphics
screens are moved up one page, starting at 3072 (&H0C00) and
ending at 15359 (&H3BFF).
On start up the Dragon does a PCLEAR4 and in consequence the
memory available for program use starts at 7680, or 9216
with the DOS Controller in place.

DRAGON 64 in 64 MODE.

Same as above, except the BASIC ROM is moved from 32768
(&H8000) to 49152 (&HC000), which gives a substantial
increase in memory available for program use, but means that
disks cannot be used as the ROM overlays the Cartridge area.
Programs exist to overcome this problem however.

<pre>13824 - 49151 3600 - BFFF PROGRAM USE
49152 - 65279 C000 - FEFF BASIC ROM
65280 - 65375 FF00 - FF5F INPUT/OUTPUT
65376 - 65503 FF60 - FFDF SAM CONTROL BITS
65504 - 65535 FFE0 - FFFF MPU VECTORS</pre>

NOTE

The following pages contain details of the Dragon's memory,
both the Basic work pages and the Basic ROM. While every
effort has been made to ensure the accuracy of these
details, the Editor has had to rely on a number of sources
and it has not been possible to check them all.
Where possible details have also been given of the Tandy
Coco2 equivalent, making it possible for the conversion of
programs from American sources. In so doing you are reminded
that the Coco disk system differs greatly from Dragondos and
is closer to the cassette system in the way that it handles
data files.
One other major difference is the way that graphic binary
files are stored, they are usually 512 bytes higher in
memory than Dragon graphics.

== MEMORY MAP DETAILS ==
<pre>
0 0 BREAK message flag
1 1 STRING delimiting character
2 2 Another delimiting character
3 3 General counter
4 4 Count of IF's seen looking for ELSE
5 5 DIM flag
6 6 VARIABLE type flag 0=numeric 255=string
7 7 Garbage collection flag
8 8 Subscript allowed flag
9 9 INPUT/READ flag
10 A Arithmetic use
11) B) String pointer - first free temporary
12) C)
13) D) String pointer - last used temporory
15-24 E-18 Temporary results
25/26 19/1A Start address of Basic program
27/28 1B/1C Start address of simple variables table
see D User 1/86 p38 for details of
variables.
29/30 1D/1E Start address of ARRAY table
31/32 1F/20 End of storage (last byte used by Basic)
33/34 21/22 Top of Stack. ((Stack grows down)
35/36 23/24 Top of free STRING space. By subtracting the
contents of 33/34 you get free string space
37/38 25/26 Pointer to STRING in string space
39/40 27/28 Top of RAM available to Basic
41/42 29/2A Line number used in 'CONT' command
43/44 2B/2C Temp G.P. line number store
45/46 2D/2E Pointer to statement to be executed
47/48 2F/30 Direct mode command text pointer
49/50 31/32 Current DATA statement line number
51/52 33/34 Address of next item in current data sta'nt
53/54 35/36 Address of keyboard input buffer
55/56 37/38 Pointer to VARIABLE last in use
57/58 39/3A VARPTR address of variable last in use
59/78 3B/4E Evaluation variables
65/66 41/42 High end destination address for block move
67/68 43/44 High end origin address
69/70 45/46 Low end destination address
71/72 47/48 Low end origin address
79/84 4F/54 Floating Point Accumulator: No 1
79 4F Exponent )
80/83 50/53 Mantissa ) Details of FPA
84 54 Sign )
85 55 Temporary sign of FAC
86 56 String variable length
92/97 5C/61 Floating Pt Acc No 2: details as before
98 62 Sign comparison
99 63 Extended precision byte-Coco
104/105 68/69 Current line number (65535 in direct mode)
106 6A VDU Comma field width (default 16)
107 6B VDU Last Comma field (screen width - above)
108 6C VDU Current column number (0 - 31)
109 6D VDU Line width. No of characters per line
110 6E Cassette I/O flag. Set FF on input incurring
111 6F DEVN: re text output: 0=VDU 255=tape 254=prt
112 70 Cassette EOF flag: EOF reached if non zero
113 71 Restart flag. If<>$55 - cold start on reset
114/115 72/73 Restart vector. If flag=$55 & vector points
points to a NOP then warm start else
a cold start.
116/117 74/75 Physical end of RAM
120 78 Cassette status:0=closed 1=input 2=output
121 79 I/O buffer size
122/3 7A/B Header buffer address:where f'name block is
124 7C Cassette block type:
0=f'name block 1=data block 255=EOF marker b
125 7D BLKLEN:Cass Block length:Bytes to read/write
126/7 7E/F Cassette I/O buffer address
128 80 Used internally to calculate the checksum
129 81 I/O error code 1=CRC 2=attempt load into RAM
130/2 82/4 Temp store used by COS
133 85 Last sine value
134 86 Data for Lo-res SET/RESET routine
135 87 ASCII code of last key pressed
136/7 88/89 Current VDU cursor address (ie screen pos)
138/9 8A/B G.P. (16 bit) scratch pad
140 8C Sound pitch value (frequency)
141/2 8D/E GP Countdown facility (?duration of sound)
143 8F Cursor Flash Counter
144/5 90/1 Cassette leader byte count (number of &H55s)
146 92 Min Cycle width of 1200HZ - Init=12
147 93 Min Pulse width of 1200HZ - Init=0A
148 94 Max pulse width of 1200HZ - Init=12
149/50 95/6 Dragon - Motor on delay
Coco - Serial printer Baud rate constant
HEX Msb Lsb (decimal) Baud
149 150
02EB 2 235 75
01CA 1 202 120
0173 1 115 150
00BE 0 180 300
0057 0 87 600 (default)
0028 0 41 1200
0012 0 18 2400
0006 0 6 4800
0001 0 1 9600
151/2 97/8 Keyboard Scan Delay constant: Init=&H045E
153 99 Printer Comma Field Width: Default 16
154 9A Printer Last Comma Field
155 9B Printer Line Width: Set this to width 80?
156 9C Printer Head Column:same as POS(-2) in basic
157/8 9D/E Exec Entry address
159/170 9F/AA Self modifying routine which reads next char
166/7 A6/7 Address of current sig byte - next char pntr
171/4 AB/E Used by RND command
175 AF TRON/TROFF flag: Non zero - trace on
176/7 B0/1 Address os start of USR address table
178 B2 Current foreground colour
179 B3 Current Background colour
180 B4 Temp colour in use
181 B5 Byte value for current colour: ie bits set
182 B6 Graphics PMODE number in use.
183/4 B7/8 Address of LAST byte of current graphics
185 B9 Number of bytes per line in current PMODE
186/7 BA/B Address of FIRST byte: current graphics disp
188 BC Start of graphics pages (MSB) defaults to 06
Changed to 0C by Dragondos
189/90 BD/E Current X Cursor position (not available
191/2 BF/C0 Current Y Cursor position (n.a.)
193 C1 Colour Set currently in use
194 C2 Plot/Unplot flag:0=Reset, Non-zero=Set
195/96 C3/4 Current Horizontal Pixel number
197/8 C5/6 Current Vertical Pixel number
199/200 C7/C8 Current X cursor co-ordinate
201/2 C9/CA Current Y cursor co-ordinate
203/4 CB/CC Circle command X co-ordinate
205/6 CD/CE Circle command Y co-ordinate
207/8 CF/D0 RENUMber increment value
209/10 D1/2 RENUMber Start line (original number)
211/2 D3/4 CLOADM: 2's complement load offset value
213/4 D5/6 RENUMber New Start line (new number)
215 D7 Editor line length - not user available
216/221 D8/DD Graphics use
222 DE Current octave in use (0 - 4)
223/4 DF/E0 Volume data for volume setting in PLAY
225 E1 Current note length in PLAY
226 E2 Current TEMPO for PLAY command
227/8 E3/4 Music duration count
229 E5 Music dotted note flag
230 E6 Coco - Baud rate constant
231 E7 Coco - Input timeout constant
232 E8 Current ANGLE used in DRAW routine
233 E9 Current SCALE used in DRAW routine
234 EA Disk operation code-what operation specified
235 EB Disk Drive number(1 - 4) Coco(1 - 3)
236 EC Disk read/write TRACK number
237 ED Disk read/write SECTOR number
238/9 EE/F Disk read/write Sector Buffer address
240 F0 Disk Error Status byte (Convt to DDOS code)
241 F1 Disk File Control Block number (1 - 10)
242 F2 Number of bytes in Disk buffer area
243 F3 No of bytes to transfer to/from buffer
244 F4 Number of SIDES/TRACKS for current drive
00=1 side 40 tracks 01=2 sides 40 tracks
FF=1 side 80 tracks FE=2 sides 80 tracks
The FORMAT of a disk is taken from the last
few bytes of Sector 1 of Track 20 in Drogon
DOS, on first access of disk after switch on
or RESET.
245 F5 File Read/write flag
0=read, 1=write & FF=verify
246 F6 Disk I/O in progress flag
256/8 100/2 SWI3 JUMP VECTOR - called from &HFFF2
Execution of a SWI3 instruction of &H113F
will stack Registers and jump here
259/61 103/5 SWI2 JUMP VECTOR - called from &HFFF4
Execution of a SWI2 instruction of &H103F
will stack registers and jump here
262/4 106/8 SWI1 JUMP VECTOR - called from &HFFFA -&H3F
will stack registers and jump here
265/7 109/B NMI JUMP VECTOR -non-maskable interrupt
called from &HFFFC, set to &H7ED7AE JUMPD7AE
by initialisation of disk operating system
in the Coco. Okay for Dragon?
268/70 10C/E IRQ JUMP SECTOR - Interrupt request called
from &HFFF8. Set to &H7EA9B3 to initialise
Basic, Set to &H7E894C for initialisation of
extended Basic or set to &H7ED7BC for the
initialisation of DOS in the Coco.
271/3 10F/111 FIRQ JUMP VECTOR - Fast interrupt request
called from &HFFF6, set to &H7EA0F6 by the
initialisation of Basic and causes a jump to
the Cartridge Port in the Coco.
274/6 112/4 In Coco this is EXEC of USR basic function
274/5 112/3 Timer - current value of system timer
In both Dragon and Coco (double function)
277/81 115/9 Random number seeds used in RND function
282/7 11A/F Unused in Dragon
282 11A Coco - Caps lock 1=lock 0=unlock (lower case
283/4 11B/C Coco - keyboard delay constant
285/7 11D/F Coco - Vector to 45509 (JUMP $8489)
288 120 Number of Basic commands (reserved words)
289/90 121/2 Address of list of Basic commands
291/2 123/4 Address of Command Despatch Table
293 125 Number of Basic functions
294/5 126/7 Address of list of Basic functions
296/7 128/9 Address of Function Despatch Table
298/307 12A/133 As for 288 to 297, but in Dragon refers to
Disk commands and functions, but in the Coco
to Extended Basic commands and functions.
308/317 134/13D These addresses as above re COCO disks.
308/327 134/147 DRAGON - USR Table (20 bytes 2 each USR)
This USR table is switched to 1667 to 1686,
or Hex 683 to 696 when DOS is connected and
is replaced with Disk Stub3 which acts as a
terminator.
328 148 PRINTER AUTO LF/CR Flag
329 149 Dragon - Caps Lock flag:non zero=upper case
330 14A Number of chars in end of line sequence(1-4)
331/4 14B/E End of Line Characters: Set to CR/LF/NUL/NUL
This sequence is sent to printer when a
carriage return is output.
336/45 150/9 Dragon Keyboard 'Roll-over' table
338/45 152/9 Coco Keyboard 'Roll-over' table
</pre>

DRAGON/COCO KEYBOARD ROLLOVER TABLE
<pre>
Response:
Address 191 223 239 247 251 253 254
Dec Hex D C D C D C D C D C D C D C
338 152 ENT ENT X 8 P 0 H X @ P 8 H 0 @
339 153 CLR CLR Y 9 Q 1 I Y A Q 8 I 1 A
340 154 BRK BRK Z : R 2 J Z B R : J 2 B
341 155 ; S 3 K C S ; K 3 C
342 156 , T 4 L D T , L 4 D
343 157 - U 5 M E U - M 5 E
344 158 . V 6 N F V . N 6 F
345 159 SPC / W 7 O SPC G W / O 7 G
</pre>
RESPONSE IS 255 OR &HFF IF NO KEY IS PRESSED
<pre>
346 15A Right Joystick(0) - X value
347 15B Right Joystick(1) - Y value
348 15C Left Joystick (2) - X value
349 15D Left Joystick (3) - Y value

350 to 424 15E to 1A8 RAM HOOKS (each 3 bytes)
350/2 15E/160 Device Open- called just before OPEN command
353/5 161/3 Device Number-called when a DEVN is verified
356/8 164/6 Device Initialisation- called before setting
up the Device parameters in Loctn 106 to 109
359/61 167/9 OUTPUT CHAR TO DEVN:called just before out-
putting char in A Reg to DEVN
362/4 16A/C INPUT CHAR FROM DEVN: called just before
inputting a char from DEVN into A Register
365/7 16D/F INPUT FILE: called just before inputting a
file using INPUT
368/70 170/2 OUTPUT FILE: called just before outputting
to a file using PRINT
371/3 173/5 CLOSE ALL FILES: called before all files are
closed, action only taken if Cassette open
374/6 176/8 CLOSE FILE: called before device is CLOSED
action only taken if DEVN is -1 (tape)
377/9 179/B COMMAND INTERPRETER: called before interpret
of token in A Reg as command, used by Delta
380/2 17C/E RE-REQUEST INPUT. Called before requesting
more data from keyboard- ie before ?? prompt
383/5 17F/181 CHECK KEYS. Called before keyboard scanned
for BREAK and SHIFT/@. Keyboard not scanned
if DEVN is -1.
386/8 182/4 LINE INPUT FILE. Called before Line Input is
executed on current DEVN
389/91 185/7 CLOSE FILE & COMMAND. Called before closing
an ASCII file just read in as a Basic prog'm
by CLOAD & returning to COMMAND mode.
392/4 188/A CHECK EOF. Called before checking for EOF
for current DEVN
395/7 18B/D EVALUATE EXPRESSION. (obvious)
398/400 18E/190 USER ERROR TRAP. Can be patched by the user,
that is in Basic, to trap error messages.
401/3 191/3 SYSTEM ERROR TRAP. Can be patched by the
'system', ie Basic extension ROMs to trap
errors (used by Dragondos)
404/6 194/6 RUN LINK. Called when RUN command is about
to be executed. Patched by DDOS to allow a
disk filename to be specified.
407/9 197/9 RESET BASIC MEMORY. Called from two routines
in ROM before Basic Memory vectors are
changed, ie by entering or editing lines,
running programs etc.
410/2 19A/C GET NEXT COMMAND. Called before reading in
the next Basic command to be executed while
program is running.
413/5 19D/F ASSIGN STRING VARIABLE. (obvious)
416/8 1A0/2 SCREEN ACCESS. Called before the CLS,GET and
PUT commands are executed.
419/21 1A3/5 TOKENISE LINE. Called before an ASCII line
is tokenised in internal Basic format
422/4 1A6/8 DETOKENISE LINE. Called before a Tokenised
line is converted to ASCII characters
425/464 or 1A9/1D0 STRING BUFFER AREA
465 1D1 Cassette filename length
466/73 1D2/9 Cassette filename to search for/or write out
474/728 or 1DA/2D8 CASSETTE FILE DATA BUFFER
Area of memory used to load filename block &
ASCII data blocks - if this contains a file-
name block then this can be peeked (474-488)
474/81 1DA/1E1 Cassette filename (in buffer)
482 1E2 File type: 0=token basic 1=ASCII 2=binary
483 1E3 ASCII flag: 0=binary, non-zero=ASCII files.
484 1E4 Gap flag: 1=continuous, 255(FF)=gapped files
485/6 1E5/6 Execution address of machine code file
487/8 1E7/8 Load address of ungapped machine code file
729/33 2D9/C Basic line input buffer preamble
734/984 2DD/3D8 Basic line input buffer
985/1002 3D9/EA BUFFER space
1003/20 3EB/3FC Unused
1021/2 3FD/E End of line delay - RS 232 port on D64
1023 3FF D64 RS 232 port Baud rate controller port
1024) 400) TEXT SCREEN
1535) 5FF) Default area.
</pre>
The Coco Buffer areas are slightly different:
733/988 2DD/3DC 255 byte Keyboard buffer
737/827 2E1/33B 90 byte Screen buffer

The Disk Work area is from 1536 to 3071, or &H0600 to &H0BFF
Otherwise if disks are not installed these addresses are in
respect of the first of the Graphic pages, but with the DOS
installed the Graphics page 1 starts at 3072 (&H0C00).

== DRAGONDOS WORK SPACE ==
<pre>
1536 0600 Start of Disk work space or Graphics Page 1
when Disk cartridge not installed
1541 0605 Countdown to Disk motor off: Off when zero
1544 0608 Auto Verify ON/OFF: 0=off else checks sector
1546 060A Current Default drive No. Used when no Drive
number is specified in the command
1549/50 060D/E Auto command line number in use
1551/2 060F/10 Auto command increment value
1553 0611 Program LOAD/RUN flag: 0=Load else Load/RUN
1555 0613 Auto command ON/OFF flag: 0=off else Auto on
1556 0614 Error command ON/OFF flag: 0=off else ERR on
1557/8 0615/6 ERROR trap line number: Basic line error rtn
1559/60 0617/8 ERL: line number of last error
1561 0619 ERR: Error code of last basic error
1562/3 061A/B Address of start of statement in error
1564/9 061C/21 Drive 1 details
1570/5 0622/7 Drive 2 details
1576/81 0628/D Drive 3 details
1582/7 062E/33 Drive 4 details
1588) 0634) Disk Buffers 1 to 4 details, 7 bytes each
1615) 064F)
1616/66 0650/82 Current Drive information
1618/9 0652/3 Start address of program loaded
1620/1 1654/5 Length of program loaded
1622/3 1656/7 Entry (EXEC) address of M/code program
1667/86 1683/96 USR Vector table: relocated from 308-327(dec
1687 to 1706) Disk Drive Parameter table
0697 to 06AA) 4 bytes per parameter - 1 for each drive
1687/90 0697/A On Line Flag: Non zero means dive on line
1691/4 069B/E Current Track, if Drive on line
1695/8 069F/A2 Head Stepping rate: This should only be
changed if slower drives are used.
1699/702
06A3/6 Disk Tracks on each drive
1703/6 06A7/A Disk Sectors per track on each drive
1707/24 06AB/BC Directory Sector status
1725/2034 File Control Blocks: 10 in all: One for each
6BD/7F2 open file: Each FCB 32 bytes long
2035/47 7F3/F Temporary variables
2048/3071 )Disk Buffers: 4 in all, each 256 bytes long
800/BFF)

3072 0C00 Start of Graphic Page 1 when disks in place
otherwise start of Graphic Page 2 for tapes.
</pre>

== BASIC INTERPRETER CODES ==
<pre>
32768 8000 Hardware initialisation
32771 8003 Software initialisation
32774 8006 POLCAT:Keyboard input:put into Register A
32777 8009 Cursor Blink
32780 800C CHROUT:Write character in Reg A to screen
32783 800F Writes out character in Reg A to printer
32786 8012 Joystick input:stored in addresses 346/9 dec
32789 8015 Cassette on
32792 8018 Cassette off
32795 801B Write leader to cassette (or A00C)
32798 801E Output byte from Reg A to cassette
32801 8021 CSRDON:Cassette on, prepare for reading
32804 8024 Input one byte from cassette to Register A
32807 8027 Gets one bit in from cassette into carry
32810 802A Reads in a byte from another computer
32813 802D Sends a byte to another computer
32816 8030 Select Baud rate of communications line
</pre>
From here on the Coco equivalents are given in brackets and
only a few Hex addresses will be given
<pre>
33604 (44102) SYSERR: Generates appropriate action for
Error code in B Reg
33649 (44147) CMDMODE: prints OK prompt & returns to the
command mode
33773 (44271) BASVECT2: complete initialisation process
after Basic program loaded
33815 (44313) NEW Basic:removes current Basic program from
memory, resets stack & clears variables
33823 (44321) BASVECT1: Sets up various necessary vectors,
once a Basic program has been loaded
33844 (44339) RESETS STACK: Resets stack to initial position
all entries are lost
33951 (44446) RUN BASIC: runs a basic program in memory,
used to AUTORUN programs
34091 851B (44539) WAIT KEY: waits for a key press, and
when key pressed puts it in A Register
34935 (45382) GET EXPR: routine will evaluate & put VARPTR
address of following expression into 82/83
34951 (45398) GET STRG: compiles a string and puts it into
free string space
35236 (45671) CKCLBRAK: as for CKCOMA, but checks for a
closed bracket
35239 (45674) CKOPBRAK: as for above, but checks for an
open bracket
35242 (45677) CKCOMA: Checks to see next significant char
in command line is a comma, and if not it
produces a SYNTAX error
35244 (45679) CKCHAR: as for CKCOMA, but checks for char
in B Register
35476 (45911) GETVAR: Get VARPTR address of the follwing
variable's name
35625 (46057) GETUSR: Returns value of the argument in the
USR function as 16 bit number in D register
35632 INTCNV: pass parameters to M/code routine
35641 GIVABF:used to pass values from M/C to Basic
35893 (46322) ASSIGN-16-BIT:assigns value in D Register to
a numeric variable
35894 (46323) ASSIGN-8-BIT:assigns value in B register to
a numeric variable
36055 (46481) GARBAGE COLLECT: forces a controlled garbage
collection of string space
36255 (46681) DELVAR: frees space taken by a variable
36433 (46859) GET-8-BIT: returns value of the following
number in B Register
36483 (46909) GET-16-BIT: returns value of the following
number in X register
36522 (46948) LIST BASIC: lists basic program in memory to
to DEVN (device specified)
37025 90A1 (47448) PRINT CR/LE: moves cursor position
to start of a new line
37093 90E5 (47516) OUT STRING:Outputs a text string to
device number in DEVN
38266 957A (48588) PRINT NUMBER:outputs 16 bit number
in D Reg to DEVN
38798 978E RANDOM NUMBER: Generates an 8 bit random
number and puts it in location 278
39998 (34830) ASSIGN-16-BITB:alternative to 35893, assigns
value in Locs 82/83 to a variable
41194 A0EA (36038) WAIT WITH CURSOR:scans keyboard for
a keypress, flashing cursor at print pos.
43207 (38201) CLEAR GRAPHICS:clears current graphics
screen to data in B Register on entry
43304 (38298) SET COLOURS: sets up locations 180 & 181
43320 (38314) SELECT DISPLAY: Selects text or graphics
depending on Z condition code, if Z=1 text
43322 95AC (38316) RESET VDU: resets default VDU mode
43401 (38395) SET VDG MODE:sets VDG in mode given in A Reg
43421 (38415) SET VDG OFFSET: sets display offset for the
graphics mode
43428 (38422) SELECT VDG COL: selects required VDG colour
set from the data in location 193
43489 (38483) SELECT PAGE: on entry B reg contains page no
43536 (38530) SELECT COL SET: selects colour set 0 or 1,
according to data in B reg
43555 (38549) RESERVE HRG RAM: reserves RAM for graphics
and moves basic if necessary
44698 (39639) PLAY NOTE: A Reg contains ASC code of note,
other parameters should be set up
45137 (40118) DRAW:allows access to all facilities of DRAW
46004 (40999) RESET:resets whole works, as if reset button
has been pressed
46080 (41142) BOOT BASIC: restarts the Basic interpreter
as if on power up or reset
46410 B54A (41602) OUTCHAR:outputs character in A Reg
to device number in DEVN (location 111)
46687 (42029) CLOSE FILES: closes any open tape stream and
flushes buffer
46757 (42089) WRITE BASIC: writes current basic program to
cassette
46920 (42257) READ BINARY: reads in BIN file from tape
47283 (42625) FIND FILE: searches tape for matching filename
47411 (42753) READ 1ST BLOCK:gets filename block into tape
buffer
47422 B93E (42763) BLKIN: reads a block of data into
cassette buffer
47505 (42981) WRITE 1ST BLOCK: (obvious)
47513 B999 (42996) BLKOUT: write block of data to tape
47583 (43149) SET LRG LEVEL:on entry the X Reg contains
Lo-res screen address, B Reg colour & loc184
the OR data
47623 (43189) RESET LRG PIXEL:as above but B Reg ignored,
Pixel reset to Black
47656 (43225) CALC PIXEL POS:on entry the top of stack
must contain Lo-res vertical co-ordinate,
preceded by horizontal co-ordinate
47735 BA77 (43304) CLEAR SCREEN: clears screen to space
and 'homes' cursor
47737 BA79 (43306) CLEAR SCREEN to CHR: clears screen
to character in B Reg
47776 (43345) BEEP:sound Beep for length held in B Reg and
pitch set by location 140
47811 (43380) AUDIO OFF: disables sound:clears bit 3 65315
47813 (43382) ENABLE SOUND: enables 6 bit sound by setting
Bit 3 of 65315
47828 (43397) RESET D/A: Puts value $7E into D/A converter
address
47830 (43399) WRITE D/A: puts contents of A Reg into D/A C
47852 (43421) AUDIO ON:on entry the B Reg must be zero
48000 BB80 BOOT BASIC64K: Boots 64 mode
48053 BBB5 (41369) UPDATE CURSOR: flashes cursor
48101 BBE5 (41409) POLCAT: scans keyboard and puts the
character in A Register
48288 BCA0 (41763) CLEAR VDU LINE: clears current VDU
line from the cursor position
48299 BCAB (41738) VDU OUT: prints char in A Reg to VDU
48373 BCF5 PRINTER DIR OUT: char in A Reg sent printer
48394 BD0A PCRLF:moves print head to start of next line
48410 BD1A (41663) PRINTER OUT:Char in Reg A to printer
48449 (43426) SELECT JSK:selects joystick sources (ports -
0 - 3) from A Register
48466 BD52 (43486) READ JSKS: Updates all joystick data
locations (346/9)
48549 BDA5 (42837) BIT IN:reads a single bit(see below)
48557 BDAD (42825) BYTE IN:reads a byte into A Reg(tape
48591 (42954) MOTOR ON: tape - sets bit 3 of $FF21
48604 (42987) MOTOR OFF: tape - clears bit 3 of $FF21
48615 (42876) READ LEADER: motor on & prepares COS to read
48658 (43050) BYTE OUT: writes byte in A Reg to tape
48746 BE6A WRTLDR:turns cassette on and writes a leader
</pre>
THE FOLLOWING ARE DRAGONDOS ROUTINES
<pre>
49166 C00E LENFIL: Report file length
49168 C010 CLOSAL: Close all files
49176 C018 GETFRE: Get free space
49178 C01A DELETE: Delete a file
49180 C01C PROTECT/UNPROTECT a file
49182 C01E RENAME a file
49184 C020 GETDIR: Get directory entry
49406 C0FC WRITE SECTOR: Writes 256 bytes to disk
49412 C104 READ SECTOR: reads 256 bytes from disk
49509 C165 DRIVE INIT: initialises DOS hardware
49513 C169 HARDWARE I/O: low level command to hardware
50108 C3BC FORMAT DISK: in the DEFD drive
53581 D14D GET FREE SPACE: free bytes on current drive
54033 D311 CONVERT SECTOR:converts LSN(Logical sect no)
in Y Reg to Track/Sector
55868 DA3C DIR DSK: directory of disk in DEFD drive to
DEVN
56229 DBA5 BEEP: on entry B Reg should contain number
of beeps
56267 DBCB WAIT TIME:on entry X Reg should contain the
number of milliseconds to wait
56330 DC0A BOOT DSK: boots an OS off disk in DEFD drive
</pre>

== INPUT/OUTPUT ADDRESSES ==

<pre>
65280 FF00 Bits 0 to 6 Keyboard row input
Bit 7 joystick comparator input
FF01 PIA
65282 FF02 Bits 0 to 7 keyboard column output
FF03 PIA
FF04 ACIA - D64/Alpha
FF05 ACIA - D64/Alpha
FF06 ACIA - D64/Alpha
FF07 ACIA - D64/Alpha

65312 FF20 Bit 0 - cassette data input
1 - RS232 data output
2/7 - 6 bit D/A(.25 to 4.75 volts out)
65313 FF21 Bit 0 - control of CD
0=FIRQ to CPU disabled, 1=enabled
Bit 1 - RS 232 status input - 0=set flag falling edge CD, 1=rising edge
Bit 2 - normal Data Direction Register addsd - 0=change FF20 to DDR
Bit 3 - Cass Motor control, 0=off, 1=on
4 - always 1
5 - always 1
6 - not used
7 - CD interrupt flag
65314 FF22 Bit 0 - RS 232 data input
1 - single bit cound output
2 - RAM size input
3 - VDG Control Output CSS(color set ct)
4 - VDG Control Output GM0&NOT(INT)/EXT
5 - VDG Cont Output GM1
6 - VDG Cont Output GM2
7 - VDG Cont Output NOT(A)/G
65315 FF23 (Coco) POKE 54 to disable auto exec of cartridge
POKE 55 to enable auto execute of cartridge
Not certain re above for Dragon
Bit 0 - control of cartridge
0=FIRQ to CPU disabled, 1= enabled
Bit 1 - Interrupt input
0=sets flag on falling edge of cartridge
1=sets flag on rising edge of cartridge
Bit 2 - Normally 1, 0=changes FF22 to DDReg
3 - 6 bit sound enable
4 - always 1
5 - always 1
6 - not used
7 - Cartridge Interrupt Flag
65316 FF24 - Dragon Alpha PIA
FF25 - Dragon Alpha PIA
FF26 - Dragon Alpha PIA
FF27 - Dragon Alpha PIA
FF28 - Dragon Alpha 6850 Modem Port

</pre>

== DISK CONTROLLERS ==

<pre>

FF2C - Dragon Alpha FDC
FF2D - Dragon Alpha FDC
FF2E - Dragon Alpha FDC
FF2F - Dragon Alpha FDC

FF40 - Dragon FDC | CoCo FDC | CoCo SDC
FF41 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF42 - Dragon FDC | CoCo FDC | CoCo SDC | Becker Port (DriveWire)
FF43 - Dragon FDC | CoCo FDC | CoCo SDC
FF48 - Latch

</pre>

== DIY PROJECTS ==

<pre>
FF50 - DragonMMC
FF54 - DragonMMC
FF56 - Dragon-MSX2+ | DragonMMC
FF57 - Dragon-MSX2+
FF58 - Dragon-MSX2+
FF59 - Dragon-MSX2+
FF5A - Dragon-MSX2+
FF5B - Dragon-MSX2+
FF5C - Dragon-MSX2+
FF5D - Dragon-MSX2+
FF5E - Dragon MSX2+

FF76 - Dragon-MSX2+
FF77 - Dragon-MSX2+
FF78 - Dragon-MSX2+
FF79 - Dragon-MSX2+
FF7A - Dragon-MSX2+ | Orchestra 90
FF7B - Dragon-MSX2+ | Orchestra 90
FF7C - Dragon-MSX2+
FF7D - Dragon-MSX2+
FF7E - Dragon-MSX2+

FF90 - MooH
FF91 - MooH
FFA0 - MooH
FFA1 - MooH
FFA2 - MooH
FFA3 - MooH
FFA4 - MooH
FFA5 - MooH
FFA6 - MooH
FFA7 - MooH
FFA8 - MooH
FFA9 - MooH
FFAA - MooH
FFAB - MooH
FFAC - MooH
FFAD - MooH
FFAE - MooH
FFAF - MooH

65471 FFBF
</pre>

== SAM CONTROL BITS ==
<pre>
65472/7 FFC0/5 VDG Control Registers for 6883 SAM
Contains 3 pairs of addresses (V0-V2), and
poking any value to EVEN addresses sets Bit
Off(0) in VDG circuitry. Poking value to ODD
addresses set Bit ON(1) in 6847 VDG circuit
65472/3 FFC0/1 Control of Bit 0 (V0)
65474/5 FFC2/3 1 (V1)
65476/7 FFC4/5 2 (V2)
65478/91 Page Select Register contains 7 pairs of
FFC6/D3 (F0-F6) control Display Start address (Bin)
Address os upper left most display element=
0000+1/2*OFFSET. Poking any value to even
addresses sets Bit OFF (0) in Page select.
Poking any value to ODD addresses sets Bit
ON(1) in Page Select Circuitry.
Also BASEPAGE is set by converting binary
value of F (Bits F0 to F6) to decimal and
multiplying this decimal number by 512.
65478/9 FFC6/7 Control of Bit 0 (F0)
65480/1 FFC8/9 1 (F1)
65482/3 FFCA/B 2 (F2)
65484/5 FFCC/D 3 (F3)
65486/7 FFCE/F 4 (F4)
65488/9 FFD0/1 5 (F5)
65490/1 FFD2/3 6 (F6)

65492/3 FFD4/5 Page #1 P1 control of Bit 7: (F7) 0=Normal
65494/7 FFD6/9 Clock Speed (R0-R1) Poking any value to even
addresses sets Bit OFF (0). Poking any value
to ODD addresses sets bit ON (1).
65494/5 FFD6/7 Control of Bit R0
65496/7 FFD8/9 Control of Bit R1
R0=0, R1=0 (slow mode defa
</pre>

== MPU VECTORS ==

<pre>
65522/3 FFF2/3 SWI 3 Vector mapped to 49138/9 BFF2/3
65524/5 FFF4/5 SWI 2 vector 49140/1 BFF4/5
65526/7 FFF6/7 FIRQ vector 49142/3 BFF6/7
65528/9 FFF8/9 IRQ vector 49144/5 BFF8/9
65530/1 FFFA/B SWI 1 vector 49146/7 BFFA/B
65532/3 FFFC/D NMI vector 49148/9 BFFC/D
65534/5 FFFE/F RESET vector 49150/1 BFFE/F
</pre>