BASIC ROM reference

#FILE: $RCSfile: romref.txt $
#DESC: Dragon 32/64 ROM Reference guide
#REV: $Revision: 1.3 $
#DATE: $Date: 1995/08/18 15:37:03 $
#AUTHOR: Graham E. Kinns
#DISCLAIMER: All information provided as is etc.
#ARCHIVE: This file is part of the DRGNINFO collection of Dragon info files
#CONTACT: Comments, bugs, revisions, suggestions to
#HISTORY: 1.0 16/01/95 - Initial version split from memmap.txt
#RCSID: $Id: romref.txt 1.3 1995/08/18 15:37:03 Graham Exp $

This information was originally part of memmap.txt and started as a
brief note of the routines I found whilst compiling the memory map but
its turning into a complete Rom reference .. 

For a more detailed description of the differences between a Dragon 32
and 64, especially software in the 32k mode rom - see d64difs.txt - this
includes commented disassembly of the changes.

Format conventions:
  $xxxx references a memory address
  0xab or 0xabcd are C style hexadecimal constants
  %TITLE% shows a 'standard' assembler reference
  UPPERCASE words typically refer to Basic keywords or Assembler mneumonics
  {1} Numbers in braces refer to reference sources - see section at end

  CoCo	refers to the Tandy CoCo only
  D32	only applicable to Dragon 32
  D64	only applicable to Dragon 64
  DOS	refers to a generic DragonDos compatible unless stated otherwise
  lsb	least significant byte
  msb	most significant byte
  ptr	pointer (or address of)
  SAM	Synchronous Address Multiplexer - Motorola MC6883 or 74LS783
	device used in the Dragon to control RAM access.
  w/o	without

Additional shorthand for subroutines:
  Pre:	Registers definitely preserved
  Des:	Registers apparently destroyed
  Ret:	Explicit return values

$8000-8002	Hardware Initialisation (JMP $bb40; D64 JMP $bb3c)
$8003-8005	Software Initialisation (JMP $bb88)
$8006-8008	%POLCAT% Scans keyboard, rets value in A (JMP $bbe5)
		  Called indirectly from [$a000]
$8009-800b	%CBLINK% Cursor Blink (JMP $bbb5)
$800c-800e	%CHROUT% Write chr in A to screen (JMP $bcab)
$800f-8011	%LPOUT%	Line printer character output in A reg., forces
		  end-of-line  sequences, outputs extra spaces to cause
		  LFs etc. See: $0099-009c, $0148 (JMP $bd1a)
$8012-8014	Reads Joystick (JMP $bd52)
		  Called indirectly from [$a00a]
$8015-8017	Cassette relay on (JMP $bdcf)
$8018-801a	Cassette relay off (JMP $bddc)
$801b-801d	Write leader to cassette (JMP $be68)
		  Called indirectly from [$a00c]
$801e-8020	Output byte in A to cassette (JMP $be12)
$8021-8023	Cassette on, init for reading (JMP $bde7)
  		  Called indirectly from [$a004]
$8024-8026	Input byte from cassette into A (JMP $bdad)
$8027-8029	Get one bit from cassette to CC.C (JMP $bda5)
$802a-802c	Reads a byte from serial port (JMP $be7b)
$802d-802f	Sends a byte to serial port (D32 JMP $be7c; D64 JMP $be98)
$8030-8032	Set serial port baud rate (D32 JMP $be7d; D64 JMP $bea6)
$8033-8153	Reserved words table
$8154-81c9	Reserved words dispatch table (Tokens 0x80-0xba only)
$81ca-824f	Function words table
$8250-8293	Function words dispatch table
$8294-82a8	Another dispatch table:
		  0x79, $910e  	+
		  0x79, $9105	-
		  0x7b, $9275	*
		  0x7b, $933c	/
		  0x7f, $96a0	^
		  0x50, $8a12	AND
		  0x46, $8a11	OR
		  The related functions come from {2, p.347}
$82a9-82de	Error code table
$82df-82e5	' ERROR', 0x00
$82e6-82ea	' IN ', 0x00
$82eb-82ef	0x0d, 'OK', 0x0d, 0x00
$82f0-82f6	0x0d, 'BREAK', 0x00
$8344		System Error - generates error message according to B
		  (CoCo $ac46)
$8371		Prints OK prompt and returns to Command mode (CoCo $ac73)
$83ed		BasVect2 - completes init once BASIC program loaded
		  (CoCo $acef)
$8415		NEW token dispatch address
$8417		Erases program in memory same as NEW (CoCo $ad19) {1}
		  Called from BASIC init routine ($b3ba)
$841f		BasVect1 - sets up various vectors after a BASIC program
		  loaded (CoCo $ad21)
$8434		Resets stack - all entries are lost (CoCo $ad33)
$8448		FOR token dispatch address
$849f		RUN BASIC - runs BASIC program in mem used by Autorun
		  programs (CoCo $ad9e)
$8514		RESTORE token dispatch address
$852b		Waits for key press, returns key in A (CoCo $adfb)
$8532		END token dispatch address
$8539		STOP token dispatch address
$8560		CONT token dispatch address
$8571		CLEAR token dispatch address
$85a5		RUN token dispatch address
$85b9		GO token dispatch address
$85f3		RETURN token dispatch address
$8613		DATA token dispatch address
$8616		REM, ', ELSE token dispatch address
$8647		IF token dispatch address
$8675		ON token dispatch address
$86bc		LET token dispatch address
$8705-870b	'?REDO', 0x0d, 0x00
$872b		INPUT token dispatch address
$8777		READ token dispatch address
$8829		NEXT token dispatch address
$8877		Get expression: evaluates next expression and puts VARPTR
		  addr in $0052:0053 (CoCo $b146)
$8887		Get string: compiles a string and puts it in free string
		  space (CoCo $b156)
$89a4		CkClBrak: checks cmd line for closed bracket (CoCo $b267)
$89a7		CkOpBrak: checks cmd line for open bracket (CoCo $b26a)
$89aa		CkComa: checks next cmd line chr for a comma, if not a Syntax
		  error is generated (CoCo $b26d)
$89ac		CkChar: as for CkComa but checks for chr in B (CoCo $b26f)
$89b4		Both reserved word and function dispatch tables of Stub 1
		  at $012a point here
$8a11		OR operator dispatch address (see $8294)
$8a12		AND operator dispatch address (see $8294)
$8a8b		DIM token dispatch address
$8a94		%GETVAR% gets VARPTR addr of following variables name
		  (CoCo $b357)
$8b29		%GETUSR% returns value of arg in USR fn in D (CoCo $b3e9)
$8b2d		%INTCNV% 
$8b30		Passes parameters to machine code routine {1}
$8b39		Used to pass back values from m/c to BASIC {1}
$8b8d-$8b91	Jump to this causes ?FC ERROR
$8c31		MEM function token dispatch address
$8c35-8c3f	Assign16Bit: assigns D to numeric variable (CoCo $b4f2)
		  ?? 8c35:8c36 is a BRN
$8c36-8c3f	Assign8Bit: assigns B to numeric variable (CoCo $b4f3)
		  clears A, stores D in FAC
$8c37-8c3f	%GIVABF% returns D as 16bit val in FAC
$8c40		STR$ function token dispatch address
$8cd7		Forces String space Garbage collection (CoCo $b591)
$8d9a		Sub - 
$8d9f		%DELVAR% frees space taken by variable (CoCo $b659)
$8dc7		LEN function token dispatch address
$8dd2		CHR$ function token dispatch address
$8de6		ASC function token dispatch address
$8df1		LEFT$ function token dispatch address
$8e0e		RIGHT$ function token dispatch address
$8e15		MID$ function token dispatch address
$8e51		Get8Bit: returns value of following number in B (CoCo $b70b)
$8e5c		VAL function token dispatch address
$8e83		Get16Bit: returns value of following number in X (CoCo $b73d)
$8e96		PEEK function token dispatch address
$8e9d		POKE token dispatch address
$8ea4		LLIST token dispatch address
$8eaa		LIST token dispatch address, List Basic to DEVN
		  (CoCo $b764)
$903d		PRINT token dispatch address
$90a1		Print CR/LF: moves cursor posn to start of new line
		  (CoCo $b958)
$90e5		Out String: Prints ASCIIZ string ptd to by X to DEVN
		  (CoCo $b99c)
$9105		- operator dispatch address (see $8294)
$910e		+ operator dispatch address (see $8294)
$923c		LOG function token dispatch address
$9275		* operator dispatch address (see $8294)
$933c		/ operator dispatch address (see $8294)
$93bf-93d4	%MOVFM% Converts a 5-byte BASIC Real variable structure
		  pointed to by X to FAC at $004f {2}
$9425		SGN function token dispatch address
$942d		Jumped to from GIVABF routine at 8c37-8c3f - returns 16
		  bit value in FAC to BASIC ??
$943e		ABS function token dispatch address
$9499		INT function token dispatch address
$9564-9568	5 byte floating point number
$9569-956d	5 byte floating point number
$956e-9572	5 byte floating point number
$957a		Print Number: outputs D as number to DEVN (CoCo $bdcc)
$9697		SQR function token dispatch address
$96a0		^ operator dispatch address (see $8294)
$9713		EXP function token dispatch address
$9772		RND function token dispatch address
$978e		Random Number: generates 8bit random number in $0116
$97cb		COS function token dispatch address
$97d1		SIN function token dispatch address
$9816		TAN function token dispatch address
$9877		ATN function token dispatch address
$98e3		Called from BASIC init routine ($b3ba-)
$9956		FIX function token dispatch address
$9965		EDIT token dispatch address
$9ad9		TRON token dispatch address
$9ada		TROFF token dispatch address
$9ade		POS function token dispatch address
$9af4		VARPTR function token dispatch address
$9b84		STRING$ function token dispatch address
$9bb4		INSTR function token dispatch address
$9c3e		Assign16BitB: assigns value in $0052:0053 to a variable
		  (CoCo $880e)
$9c81		DEF token dispatch address
$9d00-9d0c	Sub
$9d0d-9d1c	Sub which returns a ptr in X to the address in the USR table
		  (ref'd by $00b0:00b1) of the USR function to be called
$9d1d		USR function token dispatch address
$9d35-9d3c	Sub which checks for '=' token, then gets value of next expression
		  by JMPing to $8e83
$9d3d		IRQ interrupt service routine
$9d59		TIMER function token dispatch address
$9d61		DEL token dispatch address
$9dfa		RENUM token dispatch address
$9fca-9fcd	3 bytes Unused ? 'UL '
$9fce-9fff	D32 - Unused 0x00
$9fd0-9fd8	D64 - Patch to support VARPTRs >32K
$9fd9-9fff	D64 - Unused 0x00
$a000-a00d	Indirect jump table
$a000:a001	Keyboard input ($8006)
$a002:a003	Character output in A to DEVNUM ($b54a)
$a004:a005	Cassette on for reading ($8021)
$a006:a007	Block input from tape ($b93e)
$a008:a009	Block output to tape ($b999)
$a00a:a00b	Joystick input ($8012)
$a00c:a00d	Write leader to cassette ($801b)
$a00e		HEX$ function token dispatch address
$a049		DLOAD token dispatch address
$a0e0		Can be used to wait for 2 keypresses {1}
$a0ea		Waits for keypress with flashing cursor (CoCo $8cc6)
$a0f4		Sub: called from DLOAD routine
$a438-a440	Sub - returns CC.C set if A is not char '0'-'9'
$a6ef		PSET token dispatch address
$a6f3		PRESET token dispatch address
$a6c7		PPOINT function token dispatch address
$a749		LINE token dispatch address
$a8c0		PCLS token dispatch address
$a8c7		Clear Graphics: Clears current graphics screen with data
		  in B (CoCo $9539)
$a8d4		COLOR token dispatch address
$a928		Set Colours: sets up locations $00b4, $00b5 (CoCo $959a)
$a938		Select Display: Selects Text (CC.Z=1) or Graphics (CC.Z=0)
		  mode (CoCo $95aa)
$a93a		Reset VDU: resets default VDU mode (CoCo $95ac)
$a989		Set VDG Mode given in A (CoCo $95fb)
$a99d		Set VDG Offset for graphics mode (CoCo $960f)
$a9a4		Set VDG Colour set from $00c1 (CoCo $9616)
$a9af		PMODE token dispatch address
$a9e1		Set Page to B (CoCo $9653)
$a9fe		SCREEN token dispatch address
$aa10		Select Colour set 0 or 1 from B (CoCo $9682)
$aa19		PCLEAR token dispatch address
$aa23		Reserve HiRes Graphics RAM, moves BASIC if nec. (CoCo $9695)
$aa81		Called from BASIC init routine ($b3ba-)
$aabe		PCOPY token dispatch address
$aada-aaef	Sub - reads and checks PCOPY page numbers
$aaf0		GET token dispatch address
$aaf3		PUT token dispatch address
$abd4-abec	5 entry table of form Word, Word, Token for matching PUT mode
$ac87		PAINT token dispatch address
$adbd		PLAY token dispatch address
$ae9a		Play Note: A contains ASCII code (CoCo $9ad7)
$af33		Sub - gets next PLAY cmd in A
$afd9		PLAY IRQ routine - branches to $bb02 if $00e3 == 0x0000
$aff6-affc	Table maps PLAY notes A-G to tone number
$affd-b014	Table
$b015-b050	Table
$b051		DRAW token dispatch address (CoCo $9cb6)
$b238		CIRCLE token dispatch address
$b39b-b3b3	Called after Hardware init routine, following a RESET
		  Inits stack, checks for Cold/warm start.  If $0071 contains
		  0x55 and $0072:0073 points to NOP then execution is passed
		  to [$0072:0073] otherwise branches to $b3ba
$b3b4-b3b9	RESET interrupt service routine (CoCo $a027)
		  Loads Y with $b39b and JMPs $8000
$b3ba		Cold start routine - clears lo mem, inits BASIC
$b400		Boot Basic: Restarts BASIC interpreter (CoCo $a0b6)
$b432-b43b	Checks for $c000:c001 = 0x444b ('DK') and branches to $c002 if
$b44f		Warm start RESET jumps here
$b469-b46e	FIRQ interrupt service routine - branches to $b46f if source
		  was cartridge else RTI
$b46f-b47a	Calls $b480 twice, then JMPs to $8000 with Y = $b47b
$b47b-b47f	CLRs $0071, then JMPs $c000 to start cartridge
$b480-b486	Loads X from $008a (0x0000) and decrements to 0x0000
		  Gives 524,298 cycle, approx. 590ms delay
$b487-b494	14 bytes copied to $009d-$00aa at startup
$b495-b4b2	30 bytes copied to $010c-$0129 at startup
$b4b3-b4cc	'(C) 1982 DRAGON DATA LTD ', 0x0d
$b4cd-b4ec	'16K BASIC INTERPRETER 1.0      ', 0x0d
$b4ed-b504	'(C) 1982 BY MICROSOFT', 0x0d, 0x0d, 0x00
$b505		Waits for key with cursor ? Called from SuperDos E6 ROM
$b54a		%OUTCHR% Sends char in A to DEVN (CoCo $a282)
		  Called indirectly from [$a002]
$b64c		CLOSE token dispatch address
$b65f		Close files: closes an open tape stream (CoCo $a42d)
$b682		CSAVE token dispatch address
$b6d4		CLOAD token dispatch address
$b6a5		Write BASIC: writes BASIC program to cassette (CoCo $a469)
$b714		Loads a headerless program from cassette {10}
$b748		Read Binary file from tape (CoCo $a511)
$b770		EXEC token dispatch address
$b796		INKEY$ function token dispatch address
$b7cc		Copy B bytes from X to U
$b800		EOF function token dispatch address
$b81e		SKIPF token dispatch address
$b828		OPEN token dispatch address
$b8b3		Find File: searches tape for matching filename (CoCo $a681)
$b933		Read 1st Block: reads filename block to cas. buf (CoCo $a701)
$b93e		%BLKIN% reads a block of data into cas. buffer (CoCo $a70b)
		  Called indirectly from [$a006]
$b981		MOTOR token dispatch address
$b991		Write 1st Block (CoCo $a7e5)
$b999-b9d1	%BLKOUT% writes a block of data to cassette (CoCo $a7f4)
		  Called indirectly from [$a008]
$b9cd-b9d1	Write byte 0x55 to cassette by JMPing to $801e
$b9cf-b9d1	JMPs to $801e to write byte in A
$b9d2		SET token dispatch address
$b9df		Set LoRes Pixel: X contains screen addr, B the colour and
		  $00b8 the OR data (CoCo $a88d)
$ba03		RESET token dispatch address
$ba07		Reset LoRes Pixel: X contains screen addr, $00b8 OR data
		  (CoCo $a8b5)
$ba28		Calc LoRes Pixel Pos: Stack contains vert and horiz coords
		  (CoCo $a8d9)
$ba44		POINT function token dispatch address
$ba5f		CLS token dispatch address
$ba77-ba85	Clears text screen (CoCo $a928)
$ba79-ba85	Clears text screen with value in B (CoCo $a92a)
$ba86-ba8d	Clears screen, prints '(C) 1982 BY MICROSOFT' msg at $b4ec 
$ba9a		SOUND token dispatch address
$baa0		Produces Beep of length B, pitch in $008c (CoCo $a951)
$bac3		Audio off: Disables sound (CoCo $a974)
$bac5-bad3	Enables sound (CoCo $a976)
$bad4-bade	Reset DAC - writes (D32 0x7e; D64 0x7c) to D/A (CoCo $a985)
$bad6-bade	Writes A to DAC - bits 0,1 of A must be 0 (CoCo $a987)
$badf		AUDIO token dispatch address
$baec		AUDIO ON: B must be 0x00 on entry (CoCo $a99d)
$baf1-bb01	Sub to init PIA for sound source output specified by the lower
		  2 bits of B - 00 = DAC, 01 = Tape input, 10 = External
		  Cart source, 11 = none
		  This code duplicates the function of $bd41-bd51, the only
		  dif being an ASRB replacing a RORB
$bb02-bb0c	Interrupt service subroutine to decrement $008d:008e, returns
		with RTI
$bb0d		JOYSTK function token dispatch address
$bb26-bb34	Jumped to from selfmodifying CHRGET routine at $009f
$bb3c-bb87	D64 - Hardware init, JMPd to from $8000, Y should contain
		  return address
$bb40-bb87	D32 - Hardware init, JMPd to from $8000, Y should contain
		  return address
$bb80-bb82	D64 - Boots 64K mode with JMP $bf49
$bb88-bb9e	Software init, JMPd to from $8003,
		  inits $008f-009b, $0148-0150 with ROM defaults
$bb92-bb94	D64 - patched to JSR $BEFF (CLR $03fd-03ff; LDU #$0148)
$bb97-bb9e	CopyXtoU - copies B bytes from X to U
$bb9f-bbab	default values for $008f-009b
$bbac-bbb4	default values for $0148-0150
$bbb5-bbcc	Flashes cursor, JMPd to from $8009 (CoCo $a199)
$bbc5-bbcc	Decrements X from 0x045e, gives 1ms delay
$bbc8-bbcc	Decrements X until 0 then returns
$bbcd-bbd9	subroutine
$bbe5-bbea	%INCH% Scans keyboard, returns char in A, JMPd to from $8006
		  (CoCo $a1c1)
$bbec		Keyboard polling sub, returns key code in A
$bca0		Clear VDU line from cursor posn (CoCo $a323)
$bcab		%OUTCH% Put char in A to screen, JMPd to from $800c
		  (CoCo $a30a)
$bcf5-bd09	%TXLPCH%  Low level routine to print char in A (CoCo $)
$bd0a		PCRLF: moves print head to next line
$bd1a		Send char in A to printer, JMPd to from $800f (CoCo $a2bf)
		D64 - This routine uses Y as well and is source of a
		bug in the Clear-J fn of Visitext Word-Pro.
$bd41-bd51	%SNDSEL%  Selects Analogue Mux channel from B.  Used to read
		  Joysticks or set sound channel (CoCo $a9a2)
		  0x00	DAC       / Right Joystick, x-axis
		  0x01	Cassette  / Right Joystick, y-axis
		  0x02	Cartridge / Left Joystick, x-axis
		  0x03	Unused    / Left Joystick, y-axis
		  See also $baf1-bb01
$bd52		%JOYIN% Reads Joysticks updates $015a-015d, JMPd to from $8012
		  (CoCo $a9de)
$bd8a-bd90	Increments $0082, samples Cassette input bit into CC.C
$bd91-bd9d	Sub
$bd97-bd9d	Sub
$bd99-bd9d	Sub
$bd9e		Sub
$bda0		Sub
$bda5		%BITIN% Get one bit from cassette to CC.C, JMPd to from $8027
		  (CoCo $a755)
$bdad		%CBIN% Input byte from cassette into A, JMPd to from $8024
		  (CoCo $a749)
$bdb9		Sub
$bdbf		Sub
$bdcf-bddb	%CASON% Motor on - Turns on relay, loads X with delay value
		  from $0095:0096 (0xda5c) then LBRAs to $bbc8, JMPd to from
		  $8015 (CoCo $a7ca)
$bddc-bde6	%CASOFF% Motor off - turns relay off, re-enables FIRQ, IRQ,
		  JMPd to from $8018 (CoCo $a7eb)
$bde7		%CSRDON% Read Leader - Disables FIRQ, IRQ, Cassette on, 
		  init for reading, JMPd to from $8021 (CoCo $a77c)
$be12-be43	%CBOUT% Output byte in A to cassette, JMPd to from $801e
		  (CoCo $a82a)
$be44-be67	36 bytes of Sine Wave data in upper 5 bits of each byte.
$be68-be7a	%WRTLDR% disables FIRQ, IRQ, turns on cassette, writes number
		  of leader bytes = 0x55 according to $0090:0091 (d32 0x0080),
		  JMPd to from $801b Pre: B,Y Des: CC,A,X Ret: X=0x0000,A=0x55
$be7b		D32 - JMPd to from $802a (RTS) 
$be7b-be97	D64 - Read byte from serial port to A, JMPd to from $802a
$be7c		D32 - JMPd to from $802d (RTS)
$be7d-be7e	D32 - JMPd to from $8030 (COMB; RTS)
$be7f-bfef	D32 - Unused area, all 0x00
$be98-bea5	D64 - Output byte in A to serial port, JMPd to from $802d
$bea6-bebd	D64 - Set baud rate in B, JMPd to from $8030
$bebe-bec4	D64 - Lookup table to map B to ACIA baud rate constant
$bec5-beda	D64 - Key scan which pauses printer during printing {8}
$beff-bf0b	D64 - Patched into Software init to CLR $03fd-03ff
$bf0c-bf1f	D64 - handles serial printer end of line delay
$bf20-bf48	D64 - IRQ routine which can be hooked in D32 mode to
		  provide 64 mode style auto-repeat and serial support
$bf49-bf59	D64 - Copies 64 mode bootstrap code to $01da and JMPs
		  EXEC points here at startup.
$bf5a-bfe8	D64 - Bootstrap routine code copied to $01da-0268
$bf9c:bf9d	D64 - '64' Can be used to check for D64 32k mode ROM
$bfe9-bfef	D64 - Unused 0x00
$bff0-bfff	6809 interrupt vectors mapped to $fff0-$ffff by SAM
$bff0:fff1	Reserved     ($0000)
$bff2:bff3	SWI3 vector  ($0100)
$bff4:bff5	SWI2 vector  ($0103)
$bff6:bff7	FIRQ vector  ($010f)
$bff8:bff9	IRQ vector   ($010c)
$bffa:bffb	SWI vector   ($0106)
$bffc:bffd	NMI vector   ($0109)
$bffe:bfff	RESET vector ($b3b4)

CoCo routines only - a complete cross-reference should really appear in
another file .. when I've got time ..

$894c		IRQ Interrupt service routine (Extended BASIC) {1}
$a0f6		FIRQ Interrupt service routine {1}
$a9b3		IRQ Interrupt service routine {1}
$ac46		System Error (Dgn $8344)
$ac73		Command Mode (Dgn $8371)
$ad19		Erases program in memory same as NEW (Dgn $8417)
$adfb		Waits for keypress (Dgn $852b)


{1}	'The Dragon Notebook', Ray Smith, NDUG.
{2}	'Inside the Dragon', Duncan Smeed and Ian Sommerville,
	   Addison-Wesley, 1983.
{3}	'TRS-80 Color Computer Tech Ref Manual', Tandy Corp, 1981.
{4}	WD2797 Floppy Disc Driver Controller Data Sheet (RS #6991).
{5}	Dragon Disc Controller Circuit Diagram, ex Dragon Data Ltd, now NDUG.
{6}	Dragon 32/64 Upgrade Manual, R. Hall, NDUG, 1985.

Various Articles appearing in Dragon User magazine:
{7}	'Inside the 32', Dave Barnish, p13, Jan 1987.
{8}	'BREAKing the '64', Martyn Armitage, p8-9, Feb 1988.
{9}	'Firmware - Part 1', Brian Cadge, p19, Sep 1985.
{10}	'Dragon Answers', Brian Cadge, p31, Sep 1985.


PC CoCo Emulator ( by Jeff Vavasour, without the excellent
debugger / monitor included with the package checking some of the above
would have been a lot harder.

Ray Smith for the Dragon Notebook which was a major source and inspiration.

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