MS-DOS v1.25 Release

v1.25/Tim_Paterson_16Dec2013_email.txt

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+From: Tim Paterson 
+To: Len Shustek 
+Date: Mon, 16 Dec 2013 10:34:17 -0800
+Subject: RE: Source code to MS-DOS 1.0
+
+
+I have found and attached the source code for MS-DOS 1.25 as shipped by Seattle Computer Products.  Version 1.25 was the first general release to OEM customers other than IBM so was used by all the first clone manufacturers.
+ 
+IBM's DOS 1.1 corresponds to MS-DOS 1.24.  There is one minor difference between 1.24 and 1.25, as noted in the revision history at the top of MSDOS.ASM.
+ 
+Of the file attached, only STDDOS.ASM/MSDOS.ASM (DOS main code) and COMMAND.ASM (command processor) would have been used by an OEM other than Seattle Computer.  The other files:
+ 
+IO.ASM - I/O system unique to SCP (equivalent to ibmbio.sys).
+ASM.ASM & HEX2BIN.ASM - Old 8086 assembler developed by SCP (used to assemble older version of DOS).
+TRANS.ASM - Z80 to 8086 assembly source code translator developed by SCP.
+ 
+I also have a 6” stack of printouts of assembly listings for some of these and probably other related programs.
+ 
+Tim Paterson
+Paterson Technology
+http://www.patersontech.com/
+ 
+ 

v1.25/source/HEX2BIN.ASM

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+; HEX2BIN  version 1.02
+; Converts Intel hex format files to straight binary
+
+FCB:	EQU	5CH
+READ:	EQU	20
+SETDMA:	EQU	26
+OPEN:	EQU	15
+CLOSE:	EQU	16
+CREATE:	EQU	22
+DELETE:	EQU	19
+BLKWRT:	EQU	40
+GETSEG:	EQU	38
+BUFSIZ:	EQU	1024
+
+	ORG	100H
+	PUT	100H
+
+HEX2BIN:
+	MOV	DI,FCB+9
+	CMP	B,[DI]," "
+	JNZ	HAVEXT
+	MOV	SI,HEX
+	MOVB
+	MOVW
+HAVEXT:
+;Get load offset (default is -100H)
+	MOV	CL,4		;Needed for shifts
+	MOV	[OFFSET],-100H
+	MOV	SI,FCB+11H	;Scan second FCB for offset
+	LODB
+	CMP	AL," "		;Check if offset present
+	JZ	HAVOFF
+	MOV	B,[SIGN],0	;Assume positive sign for now
+	CMP	AL,"+"
+	JZ	GETOFF		;Get a positive offset
+	CMP	AL,"-"
+	JNZ	GETOFF1		;If not + or -, then not signed
+	MOV	B,[SIGN],1	;Flag as negative offset
+GETOFF:
+	LODB			;Eat sign
+GETOFF1:
+	CALL	HEXCHK		;Check for valid hex character
+	JC	HAVOFF		;No offset if not valid
+	XOR	BX,BX		;Intialize offset sum to 0
+CONVOFF:
+	SHL	BX,CL		;Multiply current sum by 16
+	OR	BL,AL		;Add in current hex digit
+	LODB			;Get next digit
+	CALL	HEXCHK		;And convert it to binary
+	JNC	CONVOFF		;Loop until all hex digits read
+	TEST	B,[SIGN],-1	;Check if offset was to be negative
+	JZ	SAVOFF
+	NEG	BX
+SAVOFF:
+	MOV	[OFFSET],BX
+HAVOFF:
+	MOV	DX,STARTSEG
+	MOV	AX,DS
+	ADD	DX,AX		;Compute load segment
+	MOV	AH,GETSEG
+	INT	33
+	MOV	ES,DX
+	SEG	ES
+	MOV	CX,[6]		;Get size of segment
+	MOV	[SEGSIZ],CX
+	XOR	AX,AX
+	MOV	DI,AX
+	MOV	BP,AX
+	SHR	CX
+	REP
+	STOW			;Fill entire segment with zeros
+	MOV	AH,OPEN
+	MOV	DX,FCB
+	INT	21H
+	OR	AL,AL
+	JNZ	NOFIL
+	MOV	B,[FCB+32],0
+	MOV	[FCB+14],BUFSIZ	;Set record size to buffer size
+	MOV	DX,BUFFER
+	MOV	AH,SETDMA
+	INT	33
+	MOV	AH,READ
+	MOV	DX,FCB		;All set up for sequential reads
+	MOV	SI,BUFFER+BUFSIZ ;Flag input buffer as empty
+READHEX:
+	CALL	GETCH
+	CMP	AL,":"		;Search for : to start line
+	JNZ	READHEX
+	CALL	GETBYT		;Get byte count
+	MOV	CL,AL
+	MOV	CH,0
+	JCXZ	DONE
+	CALL	GETBYT		;Get high byte of load address
+	MOV	BH,AL
+	CALL	GETBYT		;Get low byte of load address
+	MOV	BL,AL
+	ADD	BX,[OFFSET]	;Add in offset
+	MOV	DI,BX
+	CALL	GETBYT		;Throw away type byte
+READLN:
+	CMP	DI,[SEGSIZ]
+	JAE	ADERR
+	CALL	GETBYT		;Get data byte
+	STOB
+	CMP	DI,BP		;Check if this is the largest address so far
+	JBE	HAVBIG
+	MOV	BP,DI		;Save new largest
+HAVBIG:
+	LOOP	READLN
+	JP	READHEX
+
+NOFIL:
+	MOV	DX,NOFILE
+QUIT:
+	MOV	AH,9
+	INT	21H
+	INT	20H
+
+ADERR:
+	MOV	DX,ADDR
+	JMP	SHOWERR
+
+GETCH:
+	CMP	SI,BUFFER+BUFSIZ
+	JNZ	NOREAD
+	INT	21H
+	CMP	AL,1
+	JZ	ERROR
+	MOV	SI,BUFFER
+NOREAD:
+	LODB
+	CMP	AL,1AH
+	JZ	DONE
+	RET
+
+GETBYT:
+	CALL	HEXDIG
+	MOV	BL,AL
+	CALL	HEXDIG
+	SHL	BL
+	SHL	BL
+	SHL	BL
+	SHL	BL
+	OR	AL,BL
+	RET
+
+HEXCHK:
+	SUB	AL,"0"
+	JC	RET
+	CMP	AL,10
+	JC	CMCRET
+	SUB	AL,"A"-"0"-10
+	JC	RET
+	CMP	AL,16
+CMCRET:
+	CMC
+	RET
+
+HEXDIG:
+	CALL	GETCH
+	CALL	HEXCHK
+	JNC	RET
+ERROR:
+	MOV	DX,ERRMES
+SHOWERR:
+	MOV	AH,9
+	INT	21H
+DONE:
+	MOV	[FCB+9],4F00H+"C"	;"CO"
+	MOV	B,[FCB+11],"M"
+	MOV	DX,FCB
+	MOV	AH,CREATE
+	INT	21H
+	OR	AL,AL
+	JNZ	NOROOM
+	XOR	AX,AX
+	MOV	[FCB+33],AX
+	MOV	[FCB+35],AX	;Set RR field
+	INC	AX
+	MOV	[FCB+14],AX	;Set record size
+	XOR	DX,DX
+	PUSH	DS
+	PUSH	ES
+	POP	DS		;Get load segment
+	MOV	AH,SETDMA
+	INT	21H
+	POP	DS
+	MOV	CX,BP
+	MOV	AH,BLKWRT
+	MOV	DX,FCB
+	INT	21H
+	MOV	AH,CLOSE
+	INT	21H
+EXIT:
+	INT	20H
+
+NOROOM:
+	MOV	DX,DIRFUL
+	JMP	QUIT
+
+HEX:	DB	"HEX"
+ERRMES:	DB	"Error in HEX file--conversion aborted$"
+NOFILE:	DB	"File not found$"
+ADDR:	DB	"Address out of range--conversion aborted$"
+DIRFUL:	DB	"Disk directory full$"
+
+OFFSET:	DS	2
+SEGSIZ:	DS	2
+SIGN:	DS	1
+BUFFER:	DS	BUFSIZ
+
+START:
+STARTSEG EQU	(START+15)/16
+

v1.25/source/STDDOS.ASM

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+	TITLE	MS-DOS version 1.25 by Tim Paterson     March 3, 1982
+	PAGE	60,132
+; Use the following booleans to set the switches 
+FALSE	EQU	0
+TRUE	EQU	NOT FALSE
+
+; Use the switches below to produce the standard Microsoft version of the IBM
+; version of the operating system
+MSVER	EQU	TRUE
+IBM	EQU	FALSE
+
+; Set this switch to cause DOS to move itself to the end of memory
+HIGHMEM	EQU	FALSE
+
+; Turn on switch below to allow testing disk code with DEBUG. It sets
+; up a different stack for disk I/O (functions > 11) than that used for
+; character I/O which effectively makes the DOS re-entrant.
+
+DSKTEST	EQU	FALSE
+
+	INCLUDE	MSDOS.ASM
+
+