Initial commit

Initial import of the transcribed source code from Tim Paterson's DOS listings. Co-authored-by: RichCini <rich.cini@gmail.com>
2026-04-22 01:04:31 +10:00
commit 8065d4d8be
29 changed files with 72598 additions and 0 deletions
@@ -0,0 +1,4 @@
 * -text
 LICENSE text=auto
 *.md text=auto
 *.txt text=auto
@@ -0,0 +1,613 @@
   CCCCCCCCCCCC      HHH         HHH      KKK         KKK      DDDDDDDDDDDD            SSSSSSSSSSSS      KKK         KKK
   СССССССССССС      HHH         HHH      KKK         KKK      DDDDDDDDDDDD            SSSSSSSSSSSS      KKK         KKK
   СССССССССССС      HHH         HHH      KKK         KKK      DDDDDDDDDDDD            SSSSSSSSSSSS      KKK         KKK
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD      SSS                  KKK         KKK
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD      SSS                  KKK         KKK
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD      SSS                  KKK         KKK
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD      SSS                  KKK      KKK   
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD      SSS                  KKK      KKK   
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD      SSS                  KKK      KKK   
 CCC                  HHHHHHHHHHHHHHH      KKKKKKKKK            DDD         DDD         SSSSSSSSS         KKKKKKKKK      
 CCC                  HHHHHHHHHHHHHHH      KKKKKKKKK            DDD         DDD         SSSSSSSSS         KKKKKKKKK      
 CCC                  HHHHHHHHHHHHHHH      KKKKKKKKK            DDD         DDD         SSSSSSSSS         KKKKKKKKK      
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD                  SSS      KKK      KKK   
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD                  SSS      KKK      KKK   
 CCC                  HHH         HHH      KKK      KKK         DDD         DDD                  SSS      KKK      KKK   
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD                  SSS      KKK         KKK
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD                  SSS      KKK         KKK
 CCC                  HHH         HHH      KKK         KKK      DDD         DDD                  SSS      KKK         KKK
   CCCCCCCCCCCC      HHH         HHH      KKK         KKK      DDDDDDDDDDDD         SSSSSSSSSSSS         KKK         KKK
   СССССССССССС      HHH         HHH      KKK         KKK      DDDDDDDDDDDD         SSSSSSSSSSSS         KKK         KKK
   СССССССССССС      HHH         HHH      KKK         KKK      DDDDDDDDDDDD         SSSSSSSSSSSS         KKK         KKK
   AAAAAAAAA            888888888            666666666   
   AAAAAAAAA            888888888            666666666   
   AAAAAAAAA            888888888            666666666   
 AAA         AAA      888         888      666            
 AAA         AAA      888         888      666            
 AAA         AAA      888         888      666            
 AAA         AAA      888         888      666            
 AAA         AAA      888         888      666            
 AAA         AAA      888         888      666            
 AAA         AAA         888888888         666666666666   
 AAA         AAA         888888888         666666666666   
 AAA         AAA         888888888         666666666666   
 AAAAAAAAAAAAAAA      888         888      666         666
 AAAAAAAAAAAAAAA      888         888      666         666
 AAAAAAAAAAAAAAA      888         888      666         666
 AAA         AAA      888         888      666         666
 AAA         AAA      888         888      666         666
 AAA         AAA      888         888      666         666
 AAA         AAA         888888888            666666666   
 AAA         AAA         888888888            666666666   
 AAA         AAA         888888888            666666666   
 *START* User ROS BASIC [500,500]  Job  86DOS Seq. 7115 Date 16-Jun-81 15:13:30 Monitor Microsoft 1091 603a4d80j *START*
 File: DSKC:CHKDSK.A86<055>[500,500] Created: 15-Jun-81 04:10:28 Printed: 16-Jun-81 15:32:54
 QUEUE Switches:  /FILE:ASCII /COPIES:1 /SPACING:1 /LIMIT:565 /FORMS:NORMAL
 00100	
 00200	; CHKDSK	Version 1.0	03/10/81
 00300	
 00400	; Verifies and repairs 86-DOS disk directory.
 00500	
 00600	SETDRV:	EQU	14
 00700	GETDRV:	EQU	25
 00800	GETMAP:	EQU	27
 00900	OPEN:	EQU	15
 01000	CLOSE:	EQU	16
 01100	DELETE:	EQU	19
 01200	SETDMA:	EQU	26
 01300	SRCHFST:EQU	17
 01400	SRCHNXT:EQU	18
 01500	OUTCH:	EQU	2
 01600	BLKWRT:	EQU	40
 01700	PRINTBUF:EQU	9
 01800	
 01900		ORG	100H
 02000		PUT	100H
 02100	
 02200	CHKDSK:
 02205		MOV	SP,STACK
 02300		MOV	AH,GETDRV
 02400		INT	21H
 02500		MOV	[CURDRV],AL
 02600		MOV	DL,[5CH]
 02700		OR	DL,DL
 02800		JZ	DRVSET
 02900		MOV	AH,SETDRV
 03000		DEC	DL
 03100		INT	21H
 03110		CMP	AL,DL
 03120		JA	DRVSET
 03130		MOV	DX,BADDRV
 03135	ERROR:
 03140		MOV	AH,PRINTBUF
 03150		INT	33
 03160		INT	32
 03170	
 03175	BADDSK:
 03177		MOV	AX,CS
 03178		MOV	DS,AX
 03180		MOV	AH,SETDRV
 03185		MOV	DL,[CURDRV]
 03190		INT	33
 03195		MOV	DX,DIRBAD
 03197		JP	ERROR
 03200	DRVSET:
 03202		MOV	B,[WRKDRV],DL	;Save drive indicator
 03300		MOV	AH,GETMAP
 03400		INT	21H
 03410		CMP	B,[BX],0FEH	;Check for initialized disk
 03420		JNE	BADDSK
 03500		PUSH	DS
 03600		PUSH	ES
 03700		POP	DS
 03800		MOV	[DSKSIZ],DX	;Number of allocation units
 03900		MOV	[SECSIZ],CX	;Size of physical sector
 04000		MOV	AH,0
 04100		MOV	[CLUSSIZ],AX	;Sectors per cluster
 04200		MOV	CX,DX
 04300		MOV	DI,MAP
 04400		XOR	AX,AX
 04500		REP
 04600		STOW			;Zero out allocation map
 04700		MOV	CX,AX
 04800		MOV	[ALLOC],AX	;Count of allocation units used
 04900		MOV	[FILECNT],AX	;Number of files found
 05000		MOV	[DELCNT],AX	;Number of files deleted due to error
 05100		MOV	BP,DI
 05200		MOV	[NAMTAB],BP	;First address of file list
 05300		MOV	DX,DI
 05400		MOV	AH,SETDMA
 05500		INT	21H
 05600		MOV	AH,SRCHFST
 05700		MOV	DX,ALLFILE
 05800		INT	21H
 05900		INC	AL
 06000		POP	ES		;ES:BX point to FAT
 06100		JNZ	GETFILES
 06200		JMP	COMPMAP
 06300	GETFILES:
 06400		INC	CX		;Count number of files
 06500		ADD	DI,44		;Separate in file in list by 44 bytes
 06600		MOV	DX,DI
 06700		MOV	AH,SETDMA
 06800		INT	21H
 06900		MOV	AH,SRCHNXT
 07000		MOV	DX,ALLFILE
 07100		INT	21H
 07200		INC	AL
 07300		JNZ	GETFILES	;Loop until all files are in list
 07400		MOV	[FILECNT],CX
 07500		MOV	CX,1		;File number (position in list)
 07600		MOV	DX,[DSKSIZ]
 07700		INC	DX		;Maximum cluster number
 07800		MOV	[MAXCLUS],DX
 07900		ADD	BP,34		;Point to "first cluster" entry
 08000	EACHFIL:
 08100		XOR	AX,AX		;No. of clusters in file
 08200		MOV	SI,[BP]		;First cluster of file
 08300		CMP	SI,[MAXCLUS]	;Make sure it's legal
 08400		MOV	DI,BADDIR
 08500		JA	BADFIRST
 08600		OR	SI,SI		;Check for zero-length file
 08700		JZ	HAVENDJ
 08800	SCANFAT:
 08900		MOV	DI,CX
 09000		SHL	SI
 09100		XCHG	DI,[SI+MAP-4]	;Xchange current map entry with file no.
 09200		SHR	SI
 09300		OR	DI,DI		;Should be zero for unallocated cluster
 09400		JNZ	CROSSLINK
 09500		INC	AX		;Count cluster as part of this file
 09600		CALL	UNPACK
 09700		JZ	FORCEND		;Make sure cluster knows it's allocated
 09800		CMP	DI,0FF8H	;Bigger than this means End of File
 09900	HAVENDJ:JAE	HAVEND
 10000		CMP	DI,[MAXCLUS]	;Make sure it's a legal value
 10100		JA	FORCEND
 10200		MOV	SI,DI
 10300		JP	SCANFAT		;Visit each cluster allocated to file
 10400	
 10500	BADFIRST:
 10600		PUSH	AX		;Because FILERR will pop it later
 10700		MOV	AX,CX
 10800		MOV	DX,44
 10900		DEC	AX
 11000		MUL	AX,DX		;Get position in file name table
 11100		MOV	DX,AX
 11200		ADD	DX,[NAMTAB]
 11300		MOV	AH,DELETE
 11400		INT	21H
 11405		OR	AL,AL		;SEE IF WE HAVE A VALID DIRECTORY
 11450		JZ	DISKOK
 11452		JMP	BADDSK
 11454	DISKOK:
 11500		INC	[DELCNT]	;Count one deleted file
 11600		MOV	DX,BADDIR
 11700		JP	FILERR
 11800	
 11900	CROSSLINK:
 12000		MOV	DX,LINKED
 12100		PUSH	AX
 12200		MOV	AH,PRINTBUF
 12300		INT	21H
 12400		MOV	AX,DI
 12500		CALL	PRINTNAM
 12600		MOV	DX,FILE2
 12700		MOV	AH,PRINTBUF
 12800		INT	33
 12900		MOV	AX,CX
 13000		CALL	PRINTNAM
 13100		MOV	DX,CRLF
 13200		MOV	AH,PRINTBUF
 13300		INT	33
 13400		POP	AX
 13500		ADD	[ALLOC],AX
 13600		JMP	SIZSET1
 13700	
 13800	FORCEND:
 13900	; Come here if a cluster allocated to a file contained an illegal
 14000	; link--either a zero (meaning unallocated), or a value larger than
 14100	; the maximum cluster number, but not End of File. Put an End of File
 14200	; mark there so the FAT will at least be well-formed.
 14300		MOV	DX,0FFFH
 14400		CALL	PACK
 14500		MOV	DX,BADCLUS
 14600		PUSH	AX
 14700	
 14800	FILERR:
 14900		MOV	AH,PRINTBUF
 15000		INT	21H
 15100		MOV	AX,CX
 15200		CALL	PRINTNAM
 15300		MOV	DX,CRLF
 15400		MOV	AH,PRINTBUF
 15500		INT	21H
 15600		POP	AX
 15700	
 15800	HAVEND:
 15900		ADD	[ALLOC],AX	;Total up allocated clusters
 16000		MOV	SI,AX
 16100		MOV	AX,[BP+2]
 16200		MOV	DX,[BP+4]	;AX:DX now have file length
 16300		PUSH	CX
 16400		MOV	CX,[CLUSSIZ]
 16500		DEC	CX
 16600		ADD	AX,CX
 16700		ADC	DX,0
 16800		INC	CX
 16900	SCALE:
 17000		SHR	CX
 17100		JC	SCALED
 17200		SHR	DX
 17300		RCR	AX
 17400		JP	SCALE
 17500	SCALED:
 17600		DIV	AX,[SECSIZ]
 17700		OR	DX,DX
 17800		JZ	HAVSIZ
 17900		INC	AX
 18000	HAVSIZ:
 18100		CMP	AX,SI		;See if file size corresponds with allocation
 18200		JZ	SIZSET
 18300		XOR	DI,DI
 18400		MOV	CX,[CLUSSIZ]
 18500		CALL	UNSCALE
 18600		MOV	[BP+6],SI
 18700		MOV	[BP+8],DI
 18800		MOV	DX,BP
 18900		SUB	DX,34
 19000		MOV	AH,OPEN
 19100		INT	21H
 19110		OR	AL,AL
 19120		JZ	DISKOK2
 19130		JMP	BADDSK
 19140	DISKOK2:
 19200		MOV	AX,[SECSIZ]
 19300		MOV	[BP-27+14],AX	;Make record size=sector size
 19400		MOV	CX,0
 19500		MOV	AH,BLKWRT
 19600		INT	21H
 19700		MOV	AH,CLOSE	;Write back corrected directory entry
 19800		INT	21H
 19900		MOV	AH,GETMAP
 20000		PUSH	DS
 20100		INT	33		;Make sure FAT dirty bit is still set
 20200		POP	DS
 20300		MOV	DX,BADSIZ
 20400		MOV	AH,PRINTBUF
 20500		INT	21H
 20600		POP	AX
 20700		PUSH	AX
 20800		CALL	PRINTNAM
 20900		MOV	DX,CRLF
 21000		MOV	AH,PRINTBUF
 21100		INT	21H
 21200	SIZSET:
 21300		POP	CX
 21400	SIZSET1:
 21500		ADD	BP,44		;Scan next file
 21600		INC	CX
 21700		CMP	CX,[FILECNT]
 21800		JA	COMPMAP
 21900		JMP	EACHFIL
 22000	; Now compare the allocation map we have made with the FAT. Any
 22100	; clusters not allocated in the map will be released.
 22200	COMPMAP:
 22300		XOR	AX,AX		;Keep count of clusters released
 22400		MOV	BP,MAP
 22500		MOV	SI,2		;First usable cluster number
 22600		MOV	CX,[DSKSIZ]
 22700	RELCLUS:
 22800		TEST	[BP],-1		;Allocated in our map?
 22900		JNZ	NXTCLUS		;If so, skip to next
 23000		CALL	UNPACK
 23100		JZ	NXTCLUS		;If not allocated, skip to next
 23200		XOR	DX,DX
 23300		CALL	PACK		;Change to "Free" status
 23400		INC	AX		;Count clusters released
 23500	NXTCLUS:
 23600		INC	BP
 23700		INC	BP
 23800		INC	SI
 23900		LOOP	RELCLUS
 24000		OR	AX,AX		;Any clusters released?
 24100		JZ	REPORT		;If not, do final report
 24200		MOV	BX,FREED
 24300		CALL	DISPCLUS
 24400	REPORT:
 24500	; Make status report. Include no. of files, total disk space,
 24600	; free space on disk, total memory, and free memory.
 24610		SEG	CS
 24620		MOV	DL,[CURDRV]
 24630		MOV	AH,SETDRV
 24640		INT	21H
 24700		MOV	SI,[FILECNT]
 24800		SUB	SI,[DELCNT]
 24900		XOR	DI,DI
 25000		MOV	BX,NUMFIL
 25100		CALL	DISP32BITS
 25200		MOV	AX,[DSKSIZ]
 25300		MOV	BX,DSKSPC
 25400		CALL	DISPCLUS
 25500		MOV	AX,[DSKSIZ]
 25600		SUB	AX,[ALLOC]
 25700		MOV	BX,FRESPC
 25800		CALL	DISPCLUS
 25900		MOV	AX,[2]
 26000		MOV	DX,16
 26100		MUL	AX,DX
 26200		MOV	SI,AX
 26300		MOV	DI,DX
 26400		MOV	BX,TOTMEM
 26500		CALL	DISP32BITS
 26600		MOV	AX,[2]
 26700		MOV	DX,CS
 26800		SUB	AX,DX
 26900		MOV	DX,16
 27000		MUL	AX,DX
 27100		MOV	SI,AX
 27200		MOV	DI,DX
 27300		MOV	BX,FREMEM
 27400		CALL	DISP32BITS
 27405		CALL	WRTFRC		;Force all writes and handle write
 27410					;protect violation
 27900		INT	20H		;All done
 27902	
 27904	WRTFRC:	;********************************************************
 27906		;	This code forces all writes by performing a disk
 27908		;	reset (function 13). When the attempt to write
 27910		;	the allocation table fails in the case of a write-
 27912		;	protected diskette, this logic determines if the
 27914		;	allocation table had changed and if no changes were
 27916		;	made a normal termination will be forced
 27918		;*********************************************************
 27919		MOV	AX,DS
 27920		PUSH	DS		;Must first intercept INT 24H
 27921		MOV	ES,AX
 27922		XOR	AX,AX
 27924		MOV	DS,AX
 27926		MOV	SI,90H
 27928		MOV	DI,INT24	;will move vector to local address
 27930		MOV	CX,2
 27931		CLD			;So move will increment
 27932		REP
 27934		MOVW			;Vector now locally stored
 27936		MOV	AL,24H		;
 27938		MOV	AH,37
 27940		MOV	DX,WRTPRT	;
 27942		POP	DS		;Get local segment
 27944		INT	21H		;Interrupt vector now set
 27946		MOV	AH,13
 27948		INT	21H
 27953		PUSH	ES		;Will now reset INT 24H vector
 27955		XOR	AX,AX
 27957		MOV	ES,AX
 27959		CLD
 27961		MOV	DI,90H
 27963		MOV	SI,INT24
 27965		MOV	CX,2
 27967		REP
 27969		MOVW
 27971		POP	ES
 27973		RET
 27974	
 27976	WRTPRT:	;*********************************************************
 27978		;	This logic is designed to handle the case where
 27980		;	CHKDSK found no problems and upon rewriting the
 27982		;	allocation table (by the DOS) the disk was write-
 27984		;	protected and an error thus occured. With no problems
 27986		;	this code will cause normal termination, otherwise
 27987		;	normal error handling will occur.
 27988		;*********************************************************
 27990		EI		;Run with interrupts live
 27992		AND	DI,0FFH		;See if write-protect
 27994		JNZ	WRT100		;Do normal error handling
 27996		CMP	AH,3		;File allocation write?
 27998		JNZ	WRT100		;If not do normal handling
 27999		SEG	CS
 28000		CMP	[WRKDRV],AL	;Correct drive?
 28002		JNZ	WRT100		;
 28003		SEG	CS
 28004		CMP	B,[CHGCLS],1	;Legitimate change?
 28006		JZ	WRT100		;If so do normal handling
 28007		XOR	AL,AL		;Ignore the error
 28008		IRET
 28009	WRT100:	SEG	CS
 28010		JMP	L,[INT24]	;Normal error handling
 28012	
 28014	
 28015	
 28100	UNPACK:
 28200		MOV	DI,SI
 28300		SHR	DI
 28400		ADD	DI,SI
 28500		SEG	ES
 28600		MOV	DI,[DI+BX]
 28700		TEST	SI,1
 28800		JZ	HAVCLUS
 28900		SHR	DI
 29000		SHR	DI
 29100		SHR	DI
 29200		SHR	DI
 29300	HAVCLUS:
 29400		AND	DI,0FFFH
 29500		RET
 29600	
 29700	PACK:
 29705	;*************************************************************
 29710	;	ES:BX	POINTER TO THE BASE OF THE ALLOCATION TABLE
 29715	;	SI	CLUSTER NUMBER TO BE PACKED
 29720	;	DX	POINTER TO BE PLACED IN CLUSTER (SI)
 29725	;*************************************************************
 29730		MOV	B,[CHGCLS],1	;INDICATE CLUSTER CHANGED
 29800		PUSH	SI
 29900		MOV	DI,SI
 30000		SHR	SI
 30100		ADD	SI,BX
 30200		ADD	SI,DI
 30300		SHR	DI
 30400		SEG	ES
 30500		MOV	DI,[SI]
 30600		JNC	ALIGNED
 30700		SHL	DX
 30800		SHL	DX
 30900		SHL	DX
 31000		SHL	DX
 31100		AND	DI,0FH
 31200		JP	PACKIN
 31300	ALIGNED:
 31400		AND	DI,0F000H
 31500	PACKIN:
 31600		OR	DI,DX
 31700		SEG	ES
 31800		MOV	[SI],DI
 31900		POP	SI
 32000		RET
 32100	
 32200	UNSCALE:
 32300		SHR	CX
 32400		JC	RET
 32500		SHL	SI
 32600		RCL	DI
 32700		JP	UNSCALE
 32800	
 32900	DISPCLUS:
 33000		MUL	AX,[SECSIZ]
 33100		MOV	CX,[CLUSSIZ]
 33200		MOV	SI,AX
 33300		MOV	DI,DX
 33400		CALL	UNSCALE
 33500	DISP32BITS:
 33600		PUSH	BX
 33700		XOR	AX,AX
 33800		MOV	BX,AX
 33900		MOV	BP,AX
 34000		MOV	CX,32
 34100	CONVLP:
 34200		SHL	SI
 34300		RCL	DI
 34400		XCHG	AX,BP
 34500		CALL	CONVWRD
 34600		XCHG	AX,BP
 34700		XCHG	AX,BX
 34800		CALL	CONVWRD
 34900		XCHG	AX,BX
 35000		ADC	AL,0
 35100		LOOP	CONVLP
 35200	; Conversion complete. Print 10-digit number with 2 leading blanks.
 35300		MOV	CX,1B10H
 35400		CALL	OUTWORD
 35500		MOV	AX,BX
 35600		CALL	OUTWORD
 35700		MOV	AX,BP
 35800		CALL	OUTWORD
 35900		POP	DX
 36000		MOV	AH,PRINTBUF
 36100		INT	21H
 36200		RET
 36300	
 36400	OUTWORD:
 36500		PUSH	AX
 36600		MOV	DL,AH
 36700		CALL	OUTBYTE
 36800		POP	DX
 36900	OUTBYTE:
 37000		MOV	DH,DL
 37100		SHR	DL
 37200		SHR	DL
 37300		SHR	DL
 37400		SHR	DL
 37500		CALL	DIGIT
 37600		MOV	DL,DH
 37700	DIGIT:
 37800		AND	DL,0FH
 37900		JZ	BLANKZER
 38000		MOV	CL,0
 38100	BLANKZER:
 38200		DEC	CH
 38300		AND	CL,CH
 38400		OR	DL,30H
 38500		SUB	DL,CL
 38600		MOV	AH,OUTCH
 38700		INT	21H
 38800		RET
 38900	
 39000	CONVWRD:
 39100		ADC	AL,AL
 39200		DAA
 39300		XCHG	AL,AH
 39400		ADC	AL,AL
 39500		DAA
 39600		XCHG	AL,AH
 39700		RET
 39800	
 39900	PRINTNAM:
 39910		PUSH	CX
 40000		DEC	AX
 40100		MOV	CX,44
 40200		MUL	AX,CX
 40300		MOV	SI,AX
 40400		ADD	SI,[NAMTAB]
 40500		ADD	SI,8
 40600		MOV	CX,8
 40700		MOV	AH,OUTCH
 40800		CALL	PRINTCNT
 40900		MOV	DL," "
 41000		INT	21H
 41100		MOV	CL,3
 41110		CALL	PRINTCNT
 41120		POP	CX
 41130		RET
 41140	
 41200	PRINTCNT:
 41300		LODB
 41400		MOV	DL,AL
 41500		INT	21H
 41700		LOOP	PRINTCNT
 41800		RET
 41900	
 41950	ALLFILE:DB	-1,0,0,0,0,0,6	;Extended FCB
 42000		DB	0,"???????????"
 42100		DS	25
 42200	
 42300	FILE2:	DB	"  and  $"
 42305	BADDRV:	DB	"Invalid drive specification$"
 42400	BADCLUS:DB	"Allocation error for file $"
 42500	BADDIR:	DB	"Directory error-file :    $"
 42600	LINKED:	DB	"Files cross-linked: "
 42605		DB	13,10
 42610		DB	"     $"
 42700	BADSIZ:	DB	"File size error for file  $"
 42705	DIRBAD:	DB	"Diskette not initialized $"
 42800	FREED:	DB	" bytes disk space freed",13,10,13,10,"$"
 42900	NUMFIL:	DB	" disk files",13,10,"$"
 43000	DSKSPC:	DB	" bytes total disk space",13,10,"$"
 43100	FRESPC:	DB	" bytes remain available",13,10,13,10,"$"
 43200	TOTMEM:	DB	" bytes total memory",13,10,"$"
 43300	FREMEM:	DB	" bytes free"
 43400	CRLF:	DB	13,10,"$"
 43500	
 43600	DSKSIZ:	DS	2
 43700	SECSIZ:	DS	2
 43800	CLUSSIZ:DS	2
 43805	CHGCLS:	DB	0		;IF RESET TO 1-ALLOCATION TABLE UPDATED
 43810	WRKDRV:	DB	0
 43815	INT24:	DS	4
 43900	FILECNT:DS	2
 44000	NAMTAB:	DS	2
 44100	ALLOC:	DS	2
 44200	MAXCLUS:DS	2
 44300	DELCNT:	DS	2
 44400	CURDRV:	DS	1
 44405		DS	100H
 44410	STACK:
 44500	
 44600	MAP:
@@ -0,0 +1,611 @@
 00100	
 00200	; CHKDSK	Version 1.0	03/10/81
 00300	
 00400	; Verifies and repairs 86-DOS disk directory.
 00500	
 00600	SETDRV:	EQU	14
 00700	GETDRV:	EQU	25
 00800	GETMAP:	EQU	27
 00900	OPEN:	EQU	15
 01000	CLOSE:	EQU	16
 01100	DELETE:	EQU	19
 01200	SETDMA:	EQU	26
 01300	SRCHFST:EQU	17
 01400	SRCHNXT:EQU	18
 01500	OUTCH:	EQU	2
 01600	BLKWRT:	EQU	40
 01700	PRINTBUF:EQU	9
 01800	
 01900		ORG	100H
 02000		PUT	100H
 02100	
 02200	CHKDSK:
 02205		MOV	SP,STACK
 02210		OR	AL,AL		;SEE IF INVALID DRIVE SPECIFIED
 02215		JNZ	DRVERR		;IF SO JUST EXIT
 02220		CMP	B,[5DH],20H	;MAKE SURE TYPED CORRECTLY
 02225		JNZ	PRMERR		;IF NOT PARAMETER ERROR
 02300		MOV	AH,GETDRV
 02400		INT	21H
 02500		MOV	[CURDRV],AL
 02600		MOV	DL,[5CH]
 02700		OR	DL,DL
 02800		JZ	DRVMOV
 02900		MOV	AH,SETDRV
 03000		DEC	DL
 03100		INT	21H
 03110		CMP	AL,DL
 03120		JA	DRVSET
 03130	DRVERR:	MOV	DX,BADDRV
 03135	ERROR:
 03140		MOV	AH,PRINTBUF
 03150		INT	33
 03160		INT	32
 03170	
 03171	PRMERR:	MOV	DX,INVPRM	;Invalid parameter
 03172		JP	ERROR
 03175	BADDSK:
 03177		MOV	AX,CS
 03178		MOV	DS,AX
 03180		MOV	AH,SETDRV
 03185		MOV	DL,[CURDRV]
 03190		INT	33
 03195		MOV	DX,DIRBAD
 03197		JP	ERROR
 03199	DRVMOV:	MOV	DL,AL		;Correct drive designator
 03200	DRVSET:
 03202		MOV	B,[WRKDRV],DL	;Save drive indicator
 03203		INC	DL		;FOR FCB SET
 03204		MOV	B,[ALLDRV],DL	;FCB ok now
 03205		DEC	DL
 03300		CALL	DRVXCG		;Change drives and do map read
 03410		CMP	B,[BX],0FEH	;Check for initialized disk
 03420		JNE	BADDSK
 03500		PUSH	DS
 03600		PUSH	ES
 03700		POP	DS
 03800		MOV	[DSKSIZ],DX	;Number of allocation units
 03900		MOV	[SECSIZ],CX	;Size of physical sector
 04000		MOV	AH,0
 04100		MOV	[CLUSSIZ],AX	;Sectors per cluster
 04200		MOV	CX,DX
 04300		MOV	DI,MAP
 04400		XOR	AX,AX
 04500		REP
 04600		STOW			;Zero out allocation map
 04700		MOV	CX,AX
 04800		MOV	[ALLOC],AX	;Count of allocation units used
 04900		MOV	[FILECNT],AX	;Number of files found
 05000		MOV	[DELCNT],AX	;Number of files deleted due to error
 05100		MOV	BP,DI
 05200		MOV	[NAMTAB],BP	;First address of file list
 05300		MOV	DX,DI
 05400		MOV	AH,SETDMA
 05500		INT	21H
 05600		MOV	AH,SRCHFST
 05700		MOV	DX,ALLFILE
 05800		INT	21H
 05900		INC	AL
 06000		POP	ES		;ES:BX point to FAT
 06100		JNZ	GETFILES
 06200		JMP	COMPMAP
 06300	GETFILES:
 06400		INC	CX		;Count number of files
 06500		ADD	DI,44		;Separate in file in list by 44 bytes
 06600		MOV	DX,DI
 06700		MOV	AH,SETDMA
 06800		INT	21H
 06900		MOV	AH,SRCHNXT
 07000		MOV	DX,ALLFILE
 07100		INT	21H
 07200		INC	AL
 07300		JNZ	GETFILES	;Loop until all files are in list
 07400		MOV	[FILECNT],CX
 07500		MOV	CX,1		;File number (position in list)
 07600		MOV	DX,[DSKSIZ]
 07700		INC	DX		;Maximum cluster number
 07800		MOV	[MAXCLUS],DX
 07900		ADD	BP,34		;Point to "first cluster" entry
 08000	EACHFIL:
 08100		XOR	AX,AX		;No. of clusters in file
 08200		MOV	SI,[BP]		;First cluster of file
 08300		CMP	SI,[MAXCLUS]	;Make sure it's legal
 08400		MOV	DI,BADDIR
 08500		JA	BADFIRST
 08600		OR	SI,SI		;Check for zero-length file
 08700		JZ	HAVENDJ
 08800	SCANFAT:
 08900		MOV	DI,CX
 09000		SHL	SI
 09100		XCHG	DI,[SI+MAP-4]	;Xchange current map entry with file no.
 09200		SHR	SI
 09300		OR	DI,DI		;Should be zero for unallocated cluster
 09400		JNZ	CROSSLINK
 09500		INC	AX		;Count cluster as part of this file
 09600		CALL	UNPACK
 09700		JZ	FORCEND		;Make sure cluster knows it's allocated
 09800		CMP	DI,0FF8H	;Bigger than this means End of File
 09900	HAVENDJ:JAE	HAVEND
 10000		CMP	DI,[MAXCLUS]	;Make sure it's a legal value
 10100		JA	FORCEND
 10200		MOV	SI,DI
 10300		JP	SCANFAT		;Visit each cluster allocated to file
 10400	
 10500	BADFIRST:
 10600		PUSH	AX		;Because FILERR will pop it later
 10610		MOV	[BP+2],AX	;AX is zero
 10620		MOV	[BP+4],AX	;Set size to zero so we won't change it
 10700		MOV	AX,CX
 10800		MOV	DX,44
 10900		DEC	AX
 11000		MUL	AX,DX		;Get position in file name table
 11100		MOV	DX,AX
 11200		ADD	DX,[NAMTAB]
 11300		MOV	AH,DELETE
 11303		INT	21H
 11305		PUSH	DS
 11309		PUSH	CX
 11310		PUSH	AX
 11312		CALL	DRVXCG		;Reset dirty bit to rewrite FAT
 11313		POP	AX
 11315		POP	CX
 11318		POP	DS
 11321		OR	AL,AL		;SEE IF WE HAVE A VALID DIRECTORY
 11324		JZ	DISKOK
 11327		JMP	BADDSK
 11330	DISKOK:
 11333		INC	[DELCNT]	;Count one deleted file
 11600		MOV	DX,BADDIR
 11700		JP	FILERR
 11800	
 11900	CROSSLINK:
 12000		MOV	DX,LINKED
 12100		PUSH	AX
 12200		MOV	AH,PRINTBUF
 12300		INT	21H
 12400		MOV	AX,DI
 12500		CALL	PRINTNAM
 12600		MOV	DX,FILE2
 12700		MOV	AH,PRINTBUF
 12800		INT	33
 12900		MOV	AX,CX
 13000		CALL	PRINTNAM
 13100		MOV	DX,CRLF
 13200		MOV	AH,PRINTBUF
 13300		INT	33
 13400		POP	AX
 13500		ADD	[ALLOC],AX
 13600		JMP	SIZSET1
 13700	
 13800	FORCEND:
 13900	; Come here if a cluster allocated to a file contained an illegal
 14000	; link--either a zero (meaning unallocated), or a value larger than
 14100	; the maximum cluster number, but not End of File. Put an End of File
 14200	; mark there so the FAT will at least be well-formed.
 14300		MOV	DX,0FFFH
 14400		CALL	PACK
 14500		MOV	DX,BADCLUS
 14600		PUSH	AX
 14700	
 14800	FILERR:
 14900		MOV	AH,PRINTBUF
 15000		INT	21H
 15100		MOV	AX,CX
 15200		CALL	PRINTNAM
 15300		MOV	DX,CRLF
 15400		MOV	AH,PRINTBUF
 15500		INT	21H
 15600		POP	AX
 15700	
 15800	HAVEND:
 15900		ADD	[ALLOC],AX	;Total up allocated clusters
 16000		MOV	SI,AX
 16100		MOV	AX,[BP+2]
 16200		MOV	DX,[BP+4]	;AX:DX now have file length
 16300		PUSH	CX
 16400		MOV	CX,[CLUSSIZ]
 16500		DEC	CX
 16600		ADD	AX,CX
 16700		ADC	DX,0
 16800		INC	CX
 16900	SCALE:
 17000		SHR	CX
 17100		JC	SCALED
 17200		SHR	DX
 17300		RCR	AX
 17400		JP	SCALE
 17500	SCALED:
 17600		DIV	AX,[SECSIZ]
 17700		OR	DX,DX
 17800		JZ	HAVSIZ
 17900		INC	AX
 18000	HAVSIZ:
 18100		CMP	AX,SI		;See if file size corresponds with allocation
 18200		JZ	SIZSET
 18300		XOR	DI,DI
 18400		MOV	CX,[CLUSSIZ]
 18500		CALL	UNSCALE
 18600		MOV	[BP+6],SI
 18700		MOV	[BP+8],DI
 18800		MOV	DX,BP
 18900		SUB	DX,34
 19000		MOV	AH,OPEN
 19100		INT	21H
 19110		OR	AL,AL
 19120		JZ	DISKOK2
 19130		JMP	BADDSK
 19140	DISKOK2:
 19200		MOV	AX,[SECSIZ]
 19300		MOV	[BP-27+14],AX	;Make record size=sector size
 19400		MOV	CX,0
 19500		MOV	AH,BLKWRT
 19600		INT	21H
 19700		MOV	AH,CLOSE	;Write back corrected directory entry
 19800		INT	21H
 20000		PUSH	DS
 20100		CALL	DRVXCG		;Change the drives and get the map
 20200		POP	DS
 20300		MOV	DX,BADSIZ
 20400		MOV	AH,PRINTBUF
 20500		INT	21H
 20600		POP	AX
 20700		PUSH	AX
 20800		CALL	PRINTNAM
 20900		MOV	DX,CRLF
 21000		MOV	AH,PRINTBUF
 21100		INT	21H
 21200	SIZSET:
 21300		POP	CX
 21400	SIZSET1:
 21500		ADD	BP,44		;Scan next file
 21600		INC	CX
 21700		CMP	CX,[FILECNT]
 21800		JA	COMPMAP
 21900		JMP	EACHFIL
 22000	; Now compare the allocation map we have made with the FAT. Any
 22100	; clusters not allocated in the map will be released.
 22200	COMPMAP:
 22300		XOR	AX,AX		;Keep count of clusters released
 22400		MOV	BP,MAP
 22500		MOV	SI,2		;First usable cluster number
 22600		MOV	CX,[DSKSIZ]
 22700	RELCLUS:
 22800		TEST	[BP],-1		;Allocated in our map?
 22900		JNZ	NXTCLUS		;If so, skip to next
 23000		CALL	UNPACK
 23100		JZ	NXTCLUS		;If not allocated, skip to next
 23200		XOR	DX,DX
 23300		CALL	PACK		;Change to "Free" status
 23400		INC	AX		;Count clusters released
 23500	NXTCLUS:
 23600		INC	BP
 23700		INC	BP
 23800		INC	SI
 23900		LOOP	RELCLUS
 24000		OR	AX,AX		;Any clusters released?
 24100		JZ	REPORT		;If not, do final report
 24200		MOV	BX,FREED
 24300		CALL	DISPCLUS
 24400	REPORT:
 24500	; Make status report. Include no. of files, total disk space,
 24600	; free space on disk, total memory, and free memory.
 24610		SEG	CS
 24620		MOV	DL,[CURDRV]
 24630		MOV	AH,SETDRV
 24640		INT	21H
 24700		MOV	SI,[FILECNT]
 24800		SUB	SI,[DELCNT]
 24900		XOR	DI,DI
 25000		MOV	BX,NUMFIL
 25100		CALL	DISP32BITS
 25200		MOV	AX,[DSKSIZ]
 25300		MOV	BX,DSKSPC
 25400		CALL	DISPCLUS
 25500		MOV	AX,[DSKSIZ]
 25600		SUB	AX,[ALLOC]
 25700		MOV	BX,FRESPC
 25800		CALL	DISPCLUS
 25900		MOV	AX,[2]
 26000		MOV	DX,16
 26100		MUL	AX,DX
 26200		MOV	SI,AX
 26300		MOV	DI,DX
 26400		MOV	BX,TOTMEM
 26500		CALL	DISP32BITS
 26600		MOV	AX,[2]
 26700		MOV	DX,CS
 26800		SUB	AX,DX
 26900		MOV	DX,16
 27000		MUL	AX,DX
 27100		MOV	SI,AX
 27200		MOV	DI,DX
 27300		MOV	BX,FREMEM
 27400		CALL	DISP32BITS
 27405		CALL	WRTFRC		;Force all writes and handle write
 27410					;protect violation
 27412		SEG	CS
 27414		MOV	B,DL,[CURDRV]	;Get default
 27416		MOV	AH,SETDRV	;And make it current again
 27418		INT	21H
 27900		INT	20H		;All done
 27902	
 27904	WRTFRC:	;********************************************************
 27906		;	This code forces all writes by performing a disk
 27908		;	reset (function 13). When the attempt to write
 27910		;	the allocation table fails in the case of a write-
 27912		;	protected diskette, this logic determines if the
 27914		;	allocation table had changed and if no changes were
 27916		;	made a normal termination will be forced
 27918		;*********************************************************
 27919		MOV	AX,DS
 27920		PUSH	DS		;Must first intercept INT 24H
 27921		MOV	ES,AX
 27922		XOR	AX,AX
 27924		MOV	DS,AX
 27926		MOV	SI,90H
 27928		MOV	DI,INT24	;will move vector to local address
 27930		MOV	CX,2
 27931		CLD			;So move will increment
 27932		REP
 27934		MOVW			;Vector now locally stored
 27936		MOV	AL,24H		;
 27938		MOV	AH,37
 27940		MOV	DX,WRTPRT	;
 27942		POP	DS		;Get local segment
 27944		INT	21H		;Interrupt vector now set
 27946		MOV	AH,13
 27948		INT	21H
 27953		PUSH	ES		;Will now reset INT 24H vector
 27955		XOR	AX,AX
 27957		MOV	ES,AX
 27959		CLD
 27961		MOV	DI,90H
 27963		MOV	SI,INT24
 27965		MOV	CX,2
 27967		REP
 27969		MOVW
 27971		POP	ES
 27973		RET
 27974	
 27976	WRTPRT:	;*********************************************************
 27978		;	This logic is designed to handle the case where
 27980		;	CHKDSK found no problems and upon rewriting the
 27982		;	allocation table (by the DOS) the disk was write-
 27984		;	protected and an error thus occured. With no problems
 27986		;	this code will cause normal termination, otherwise
 27987		;	normal error handling will occur.
 27988		;*********************************************************
 27990		EI		;Run with interrupts live
 27992		AND	DI,0FFH		;See if write-protect
 27994		JNZ	WRT100		;Do normal error handling
 27996		CMP	AH,3		;File allocation write?
 27998		JNZ	WRT100		;If not do normal handling
 27999		SEG	CS
 28000		CMP	[WRKDRV],AL	;Correct drive?
 28002		JNZ	WRT100		;
 28003		SEG	CS
 28004		CMP	B,[CHGCLS],1	;Legitimate change?
 28006		JZ	WRT100		;If so do normal handling
 28007		XOR	AL,AL		;Ignore the error
 28008		IRET
 28009	WRT100:	SEG	CS
 28010		MOV	SI,AX		;Save AX
 28011		PUSH	DX
 28012		MOV	DL,[CURDRV]	;Fetch current drive
 28015		MOV	AH,SETDRV
 28018		INT	33		;Drive now ok
 28019		POP	DX		;Restore DX
 28020		MOV	AX,SI		;Restore AX
 28021		SEG	CS
 28024		JMP	L,[INT24]	;Do normal recovery
 28027	
 28030	
 28060	DRVXCG:
 28061		;**********************************************
 28062		;	WILL CHANGE DEFAULT TO WRKDRV READ THE FAT
 28063		;	AND CHANGE THE DEFAULT BACK TO CURDRV
 28064		;**********************************************
 28065		SEG	CS
 28068		MOV	DL,[WRKDRV]	;Will change the default to this
 28070		MOV	AH,SETDRV
 28072		INT	33		;Default now "WRKDRV"
 28073		MOV	AH,GETMAP
 28074		INT	33
 28076		PUSH	DX
 28077		PUSH	AX
 28078		SEG	CS
 28080		MOV	DL,[CURDRV]	;Get current drive
 28082		MOV	AH,SETDRV
 28084		INT	33
 28085		POP	AX
 28086		POP	DX
 28088		RET
 28090	
 28092	
 28094	UNPACK:
 28200		MOV	DI,SI
 28300		SHR	DI
 28400		ADD	DI,SI
 28500		SEG	ES
 28600		MOV	DI,[DI+BX]
 28700		TEST	SI,1
 28800		JZ	HAVCLUS
 28900		SHR	DI
 29000		SHR	DI
 29100		SHR	DI
 29200		SHR	DI
 29300	HAVCLUS:
 29400		AND	DI,0FFFH
 29500		RET
 29600	
 29700	PACK:
 29705	;*************************************************************
 29710	;	ES:BX	POINTER TO THE BASE OF THE ALLOCATION TABLE
 29715	;	SI	CLUSTER NUMBER TO BE PACKED
 29720	;	DX	POINTER TO BE PLACED IN CLUSTER (SI)
 29725	;*************************************************************
 29730		MOV	B,[CHGCLS],1	;INDICATE CLUSTER CHANGED
 29800		PUSH	SI
 29900		MOV	DI,SI
 30000		SHR	SI
 30100		ADD	SI,BX
 30200		ADD	SI,DI
 30300		SHR	DI
 30400		SEG	ES
 30500		MOV	DI,[SI]
 30600		JNC	ALIGNED
 30700		SHL	DX
 30800		SHL	DX
 30900		SHL	DX
 31000		SHL	DX
 31100		AND	DI,0FH
 31200		JP	PACKIN
 31300	ALIGNED:
 31400		AND	DI,0F000H
 31500	PACKIN:
 31600		OR	DI,DX
 31700		SEG	ES
 31800		MOV	[SI],DI
 31900		POP	SI
 32000		RET
 32100	
 32200	UNSCALE:
 32300		SHR	CX
 32400		JC	RET
 32500		SHL	SI
 32600		RCL	DI
 32700		JP	UNSCALE
 32800	
 32900	DISPCLUS:
 33000		MUL	AX,[SECSIZ]
 33100		MOV	CX,[CLUSSIZ]
 33200		MOV	SI,AX
 33300		MOV	DI,DX
 33400		CALL	UNSCALE
 33500	DISP32BITS:
 33600		PUSH	BX
 33700		XOR	AX,AX
 33800		MOV	BX,AX
 33900		MOV	BP,AX
 34000		MOV	CX,32
 34100	CONVLP:
 34200		SHL	SI
 34300		RCL	DI
 34400		XCHG	AX,BP
 34500		CALL	CONVWRD
 34600		XCHG	AX,BP
 34700		XCHG	AX,BX
 34800		CALL	CONVWRD
 34900		XCHG	AX,BX
 35000		ADC	AL,0
 35100		LOOP	CONVLP
 35200	; Conversion complete. Print 10-digit number with 2 leading blanks.
 35300		MOV	CX,1B10H
 35400		CALL	OUTWORD
 35500		MOV	AX,BX
 35600		CALL	OUTWORD
 35700		MOV	AX,BP
 35800		CALL	OUTWORD
 35900		POP	DX
 36000		MOV	AH,PRINTBUF
 36100		INT	21H
 36200		RET
 36300	
 36400	OUTWORD:
 36500		PUSH	AX
 36600		MOV	DL,AH
 36700		CALL	OUTBYTE
 36800		POP	DX
 36900	OUTBYTE:
 37000		MOV	DH,DL
 37100		SHR	DL
 37200		SHR	DL
 37300		SHR	DL
 37400		SHR	DL
 37500		CALL	DIGIT
 37600		MOV	DL,DH
 37700	DIGIT:
 37800		AND	DL,0FH
 37900		JZ	BLANKZER
 38000		MOV	CL,0
 38100	BLANKZER:
 38200		DEC	CH
 38300		AND	CL,CH
 38400		OR	DL,30H
 38500		SUB	DL,CL
 38600		MOV	AH,OUTCH
 38700		INT	21H
 38800		RET
 38900	
 39000	CONVWRD:
 39100		ADC	AL,AL
 39200		DAA
 39300		XCHG	AL,AH
 39400		ADC	AL,AL
 39500		DAA
 39600		XCHG	AL,AH
 39700		RET
 39800	
 39900	PRINTNAM:
 39910		PUSH	CX
 40000		DEC	AX
 40100		MOV	CX,44
 40200		MUL	AX,CX
 40300		MOV	SI,AX
 40400		ADD	SI,[NAMTAB]
 40500		ADD	SI,8
 40600		MOV	CX,8
 40700		MOV	AH,OUTCH
 40800		CALL	PRINTCNT
 40900		MOV	DL," "
 41000		INT	21H
 41100		MOV	CL,3
 41110		CALL	PRINTCNT
 41120		POP	CX
 41130		RET
 41140	
 41200	PRINTCNT:
 41300		LODB
 41400		MOV	DL,AL
 41500		INT	21H
 41700		LOOP	PRINTCNT
 41800		RET
 41900	
 41950	ALLFILE:DB	-1,0,0,0,0,0,6	;Extended FCB
 42000	ALLDRV:	DB	0,"???????????"
 42100		DS	25
 42200	
 42300	FILE2:	DB	"  and  $"
 42305	BADDRV:	DB	"Invalid drive specification$"
 42306	INVPRM:	DB	"Invalid parameter$"
 42400	BADCLUS:DB	"Allocation error for file $"
 42500	BADDIR:	DB	"Directory error-file :    $"
 42600	LINKED:	DB	"Files cross-linked: "
 42605		DB	13,10
 42610		DB	"     $"
 42700	BADSIZ:	DB	"File size error for file  $"
 42705	DIRBAD:	DB	"Diskette not initialized $"
 42800	FREED:	DB	" bytes disk space freed",13,10,13,10,"$"
 42900	NUMFIL:	DB	" disk files",13,10,"$"
 43000	DSKSPC:	DB	" bytes total disk space",13,10,"$"
 43100	FRESPC:	DB	" bytes remain available",13,10,13,10,"$"
 43200	TOTMEM:	DB	" bytes total memory",13,10,"$"
 43300	FREMEM:	DB	" bytes free"
 43400	CRLF:	DB	13,10,"$"
 43500	
 43600	DSKSIZ:	DS	2
 43700	SECSIZ:	DS	2
 43800	CLUSSIZ:DS	2
 43805	CHGCLS:	DB	0		;IF RESET TO 1-ALLOCATION TABLE UPDATED
 43810	WRKDRV:	DB	0
 43815	INT24:	DS	4
 43900	FILECNT:DS	2
 44000	NAMTAB:	DS	2
 44100	ALLOC:	DS	2
 44200	MAXCLUS:DS	2
 44300	DELCNT:	DS	2
 44400	CURDRV:	DS	1
 44405		DS	100H
 44410	STACK:
 44500	
 44600	MAP:
@@ -0,0 +1,242 @@
 File 1)	DSKC:EDLIN.ASM[500,500]	created: 1231 06-MAY-1981
 File 2)	DSKC:EDLIN.A86[500,500]	created: 1007 01-JULY-1981
 1)1	;EDLIN - Simple line-oriented editor for 86-DOS  version 1.00  04/24/81
 1	FCB:	EQU	5CH
 ****
 2)	00040	;EDLIN - Simple line-oriented editor for 86-DOS  version 0.32  04/15/81
 2)	00080	FCB:	EQU	5CH
 **************
 1)1	HEADER:	DB	13,10,"EDLIN  version 1.00",13,10,"$"
 1)	NONAME:
 1)		MOV	DX,NDNAME
 1)		JMP	ERROR
 1)	SIMPED:
 ****
 2)1	00460	HEADER:	DB	13,10,"The IBM Personal Computer EDITOR",13,10
 2)	00480		DB	"Version 1.00 (C)Copyright IBM Corp 1981",13,10,"$"
 2)	00500		DB	"Licensed Material - Program Property of IBM"
 2)	00540	NONAME:
 2)	00560		MOV	DX,NDNAME
 2)	00580	ERRJ:	JMP	ERROR
 2)	00620	SIMPED:
 **************
 1)1		MOV	DX,HEADER
 1)		MOV	AH,PRINT
 1)		INT	33
 1)		CMP	B,[FCB+1]," "
 1)		JZ	NONAME
 1)		MOV	SI,BAK
 ****
 2)1	00680	;	MOV	DX,HEADER
 2)	00700	;	MOV	AH,PRINT
 2)	00720	;	INT	33
 2)	00740		CMP	B,[FCB+1]," "
 2)	00760		JZ	NONAME
 2)	00780		OR	AL,AL
 2)	00800		MOV	DX,BADDRV
 2)	00820		JNZ	ERRJ
 2)	00840		MOV	SI,BAK
 **************
 1)1		ADD	CX,AX		;3/4 of available memory
 1)	;Read in input file
 ****
 2)1	02200		MOV	[ONE4TH],CX	;Save amount of 1/4 full
 2)	02220		ADD	CX,AX		;3/4 of available memory
 2)	02240		MOV	DX,CX
 2)	02260		ADD	DX,START
 2)	02280		MOV	[THREE4TH],DX	;Save pointer to 3/4 full
 2)	02300	;Read in input file
 **************
 1)1		DEC SI
 1)		CALL	GETNUM
 ****
 2)1	03140		DEC	SI
 2)	03160		CALL	GETNUM
 **************
 1)1		AND	AL,5FH
 1)		MOV	DI,COMTAB
 ****
 File 1)	DSKC:EDLIN.ASM[500,500]	created: 1231 06-MAY-1981
 File 2)	DSKC:EDLIN.A86[500,500]	created: 1007 01-JULY-1981
 2)1	03305		CMP	AL,5FH
 2)	03310		JBE	UPCASE
 2)	03320		AND	AL,5FH
 2)	03325	UPCASE:
 2)	03340		MOV	DI,COMTAB
 **************
 1)1		SHL	BX
 ****
 2)1	03460		MOV	AX,[PARAM2]
 2)	03480		OR	AX,AX
 2)	03500		JZ	PARMOK
 2)	03520		CMP	AX,[PARAM1]
 2)	03540		JB	COMERR		;Param. 2 must be >= param 1
 2)	03560	PARMOK:
 2)	03580		SHL	BX
 **************
 1)1		JP	COMMAND
 1)	GETNUM:
 ****
 2)1	03880		JMP	COMMAND
 2)	03940	GETNUM:
 **************
 1)1	NUMLP:
 1)		CMP	AL,"0"
 1)		JB	RET
 1)		CMP	AL,"9"
 1)		JA	RET
 1)		SUB	AL,"0"
 ****
 2)1	04080		MOV	CL,0		;Flag no parameter seen yet
 2)	04100	NUMLP:
 2)	04120		CMP	AL," "
 2)	04140		JB	NUMCHK
 2)	04160		CMP	AL,"9"
 2)	04180		JA	NUMCHK
 2)	04200		CMP	DX,6553		;Max line/10
 2)	04220		JAE	COMERR		;Ten times this is too big
 2)	04240		MOV	CL,1		;Parameter digit has been found
 2)	04260		SUB	AL,"0"
 **************
 1)1	CURLIN:
 ****
 2)1	04460	NUMCHK:
 2)	04480		CMP	CL,0
 2)	04500		JZ	RET
 2)	04520		OR	DX,DX
 2)	04540		JZ	COMERR		;Don't allow zero as a parameter
 2)	04560		RET
 2)	04600	CURLIN:
 **************
 1)1	APPEND:
 1)		TEST	B,[HAVEOF],-1
 1)		JNZ	NOMORE
 1)		MOV	DX,[ENDTXT]
 1)		MOV	DI,DX
 ****
 File 1)	DSKC:EDLIN.ASM[500,500]	created: 1231 06-MAY-1981
 File 2)	DSKC:EDLIN.A86[500,500]	created: 1007 01-JULY-1981
 2)1	05380	NOMOREJ:JMP	NOMORE
 2)	05420	APPEND:
 2)	05440		TEST	B,[HAVEOF],-1
 2)	05460		JNZ	NOMOREJ
 2)	05480		MOV	DX,[ENDTXT]
 2)	05500		CMP	[PARAM1],0	;See if parameter is missing
 2)	05520		JNZ	PARMAPP
 2)	05540		CMP	DX,[THREE4TH]	;See if already 3/4ths full
 2)	05560		JAE	RET		;If so, then done already
 2)	05580	PARMAPP:
 2)	05600		MOV	DI,DX
 **************
 1)1		MOV	BX,[PARAM1]
 1)		CMP	BX,1
 1)		SBC	BX,0		;Make a zero a -1
 1)		XOR	DX,DX
 1)		CALL	SCANLN		;Look for BX lines
 ****
 2)1	05900		XOR	DX,DX
 2)	05920		MOV	BX,[PARAM1]
 2)	05940		OR	BX,BX
 2)	05960		JNZ	COUNTLN
 2)	05980		MOV	AX,DI
 2)	06000		ADD	AX,CX		;First byte after loaded text
 2)	06020		CMP	AX,[THREE4TH]	;See if we made 3/4 full
 2)	06040		JBE	COUNTLN
 2)	06060		MOV	DI,[THREE4TH]
 2)	06080		MOV	CX,AX
 2)	06100		SUB	CX,DI		;Length remaining over 3/4
 2)	06120		MOV	BX,1		;Look for one more line
 2)	06140	COUNTLN:
 2)	06160		CALL	SCANLN		;Look for BX lines
 **************
 1)1	EOFCHK:
 ****
 2)1	06640	NOMORE:
 2)	06660		MOV	DX,EOF
 2)	06680		MOV	AH,PRINT
 2)	06700		INT	33
 2)	06720		RET
 2)	06740	EOFCHK:
 **************
 1)1	NOMORE:
 1)		MOV	DX,EOF
 1)		MOV	AH,PRINT
 1)		INT	33
 1)		RET
 1)	WRITE:
 ****
 2)1	06880	WRITE:
 **************
 1)1		MOV	BX,[CURRENT]
 1)		DEC	BX
 1)	WRT:
 ****
 2)1	06960		MOV	CX,[ONE4TH]
 File 1)	DSKC:EDLIN.ASM[500,500]	created: 1231 06-MAY-1981
 File 2)	DSKC:EDLIN.A86[500,500]	created: 1007 01-JULY-1981
 2)	06980		MOV	DI,[ENDTXT]
 2)	07000		SUB	DI,CX		;Write everything in front of here
 2)	07010		JBE	RET
 2)	07020		CMP	DI,START	;See if there's anything to write
 2)	07040		JBE	RET
 2)	07060		XOR	DX,DX
 2)	07080		MOV	BX,1		;Look for one more line
 2)	07100		CALL	SCANLN
 2)	07120		JP	WRTADD
 2)	07140	WRT:
 **************
 1)1		MOV	CX,DI
 ****
 2)1	07180	WRTADD:
 2)	07200		MOV	CX,DI
 **************
 1)1		INC	DX
 ****
 2)1	12680		JAE	SOMELEFT
 2)	12700		MOV	[SRCHCNT],0
 2)	12720	SOMELEFT:
 2)	12740		INC	DX
 **************
 1)1		MOV	[CURRENT],BX
 1)		MOV	[POINTER],DI
 1)		PUSH	DI
 ****
 2)1	16620		PUSH	BX
 2)	16660		PUSH	DI
 **************
 1)1		XOR	CX,CX
 1)		JP	REPLACE
 1)	NOCOM:
 ****
 2)1	16862		JBE	COMERRJ
 2)	16864		POP	[CURRENT]
 2)	16866		MOV	[POINTER],DI
 2)	16880		XOR	CX,CX
 2)	16900		JP	REPLACE
 2)	16910	COMERRJ:JMP	COMERR
 2)	16960	NOCOM:
 **************
 1)1		MOV	BX,-2		;Write max. no of lines
 1)		CALL	WRT
 ****
 2)1	20480		MOV	BX,-1		;Write max. no of lines
 2)	20500		CALL	WRT
 **************
 1)1	NDNAME:	DB	"File name must be specified$"
 ****
 2)1	21760	BADDRV:	DB	"Invalid drive or file name$"
 2)	21780	NDNAME:	DB	"File name must be specified$"
 **************
 1)1	END:	DS	2
 ****
 2)1	22340	ONE4TH:	DS	2
 File 1)	DSKC:EDLIN.ASM[500,500]	created: 1231 06-MAY-1981
 File 2)	DSKC:EDLIN.A86[500,500]	created: 1007 01-JULY-1981
 2)	22360	THREE4TH:DS	2
 2)	22380	END:	DS	2
 **************
@@ -0,0 +1,560 @@
 00100	
 00200	; CHKDSK	Version 1.0	03/10/81
 00300	
 00400	; Verifies and repairs 86-DOS disk directory.
 00500	
 00600	SETDRV:	EQU	14
 00700	GETDRV:	EQU	25
 00800	GETMAP:	EQU	27
 00900	OPEN:	EQU	15
 01000	CLOSE:	EQU	16
 01100	DELETE:	EQU	19
 01200	SETDMA:	EQU	26
 01300	SRCHFST:EQU	17
 01400	SRCHNXT:EQU	18
 01500	OUTCH:	EQU	2
 01600	BLKWRT:	EQU	40
 01700	PRINTBUF:EQU	9
 01800	
 01900		ORG	100H
 02000		PUT	100H
 02100	
 02200	CHKDSK:
 02205		MOV	SP,STACK
 02300		MOV	AH,GETDRV
 02400		INT	21H
 02500		MOV	[CURDRV],AL
 02600		MOV	DL,[5CH]
 02700		OR	DL,DL
 02800		JZ	DRVSET
 02900		MOV	AH,SETDRV
 03000		DEC	DL
 03100		INT	21H
 03110		CMP	AL,DL
 03120		JA	DRVSET
 03130		MOV	DX,BADDRV
 03135	ERROR:
 03140		MOV	AH,PRINTBUF
 03150		INT	33
 03160		INT	32
 03170	
 03175	BADDSK:
 03177		MOV	AX,CS
 03178		MOV	DS,AX
 03180		MOV	AH,SETDRV
 03185		MOV	DL,[CURDRV]
 03190		INT	33
 03195		MOV	DX,DIRBAD
 03197		JP	ERROR
 03200	DRVSET:
 03202		MOV	B,[WRKDRV],DL	;Save drive indicator
 03300		MOV	AH,GETMAP
 03400		INT	21H
 03410		CMP	B,[BX],0FEH	;Check for initialized disk
 03420		JNE	BADDSK
 03500		PUSH	DS
 03600		PUSH	ES
 03700		POP	DS
 03800		MOV	[DSKSIZ],DX	;Number of allocation units
 03900		MOV	[SECSIZ],CX	;Size of physical sector
 04000		MOV	AH,0
 04100		MOV	[CLUSSIZ],AX	;Sectors per cluster
 04200		MOV	CX,DX
 04300		MOV	DI,MAP
 04400		XOR	AX,AX
 04500		REP
 04600		STOW			;Zero out allocation map
 04700		MOV	CX,AX
 04800		MOV	[ALLOC],AX	;Count of allocation units used
 04900		MOV	[FILECNT],AX	;Number of files found
 05000		MOV	[DELCNT],AX	;Number of files deleted due to error
 05100		MOV	BP,DI
 05200		MOV	[NAMTAB],BP	;First address of file list
 05300		MOV	DX,DI
 05400		MOV	AH,SETDMA
 05500		INT	21H
 05600		MOV	AH,SRCHFST
 05700		MOV	DX,ALLFILE
 05800		INT	21H
 05900		INC	AL
 06000		POP	ES		;ES:BX point to FAT
 06100		JNZ	GETFILES
 06200		JMP	COMPMAP
 06300	GETFILES:
 06400		INC	CX		;Count number of files
 06500		ADD	DI,44		;Separate in file in list by 44 bytes
 06600		MOV	DX,DI
 06700		MOV	AH,SETDMA
 06800		INT	21H
 06900		MOV	AH,SRCHNXT
 07000		MOV	DX,ALLFILE
 07100		INT	21H
 07200		INC	AL
 07300		JNZ	GETFILES	;Loop until all files are in list
 07400		MOV	[FILECNT],CX
 07500		MOV	CX,1		;File number (position in list)
 07600		MOV	DX,[DSKSIZ]
 07700		INC	DX		;Maximum cluster number
 07800		MOV	[MAXCLUS],DX
 07900		ADD	BP,34		;Point to "first cluster" entry
 08000	EACHFIL:
 08100		XOR	AX,AX		;No. of clusters in file
 08200		MOV	SI,[BP]		;First cluster of file
 08300		CMP	SI,[MAXCLUS]	;Make sure it's legal
 08400		MOV	DI,BADDIR
 08500		JA	BADFIRST
 08600		OR	SI,SI		;Check for zero-length file
 08700		JZ	HAVENDJ
 08800	SCANFAT:
 08900		MOV	DI,CX
 09000		SHL	SI
 09100		XCHG	DI,[SI+MAP-4]	;Xchange current map entry with file no.
 09200		SHR	SI
 09300		OR	DI,DI		;Should be zero for unallocated cluster
 09400		JNZ	CROSSLINK
 09500		INC	AX		;Count cluster as part of this file
 09600		CALL	UNPACK
 09700		JZ	FORCEND		;Make sure cluster knows it's allocated
 09800		CMP	DI,0FF8H	;Bigger than this means End of File
 09900	HAVENDJ:JAE	HAVEND
 10000		CMP	DI,[MAXCLUS]	;Make sure it's a legal value
 10100		JA	FORCEND
 10200		MOV	SI,DI
 10300		JP	SCANFAT		;Visit each cluster allocated to file
 10400	
 10500	BADFIRST:
 10600		PUSH	AX		;Because FILERR will pop it later
 10700		MOV	AX,CX
 10800		MOV	DX,44
 10900		DEC	AX
 11000		MUL	AX,DX		;Get position in file name table
 11100		MOV	DX,AX
 11200		ADD	DX,[NAMTAB]
 11300		MOV	AH,DELETE
 11400		INT	21H
 11405		OR	AL,AL		;SEE IF WE HAVE A VALID DIRECTORY
 11450		JZ	DISKOK
 11452		JMP	BADDSK
 11454	DISKOK:
 11500		INC	[DELCNT]	;Count one deleted file
 11600		MOV	DX,BADDIR
 11700		JP	FILERR
 11800	
 11900	CROSSLINK:
 12000		MOV	DX,LINKED
 12100		PUSH	AX
 12200		MOV	AH,PRINTBUF
 12300		INT	21H
 12400		MOV	AX,DI
 12500		CALL	PRINTNAM
 12600		MOV	DX,FILE2
 12700		MOV	AH,PRINTBUF
 12800		INT	33
 12900		MOV	AX,CX
 13000		CALL	PRINTNAM
 13100		MOV	DX,CRLF
 13200		MOV	AH,PRINTBUF
 13300		INT	33
 13400		POP	AX
 13500		ADD	[ALLOC],AX
 13600		JMP	SIZSET1
 13700	
 13800	FORCEND:
 13900	; Come here if a cluster allocated to a file contained an illegal
 14000	; link--either a zero (meaning unallocated), or a value larger than
 14100	; the maximum cluster number, but not End of File. Put an End of File
 14200	; mark there so the FAT will at least be well-formed.
 14300		MOV	DX,0FFFH
 14400		CALL	PACK
 14500		MOV	DX,BADCLUS
 14600		PUSH	AX
 14700	
 14800	FILERR:
 14900		MOV	AH,PRINTBUF
 15000		INT	21H
 15100		MOV	AX,CX
 15200		CALL	PRINTNAM
 15300		MOV	DX,CRLF
 15400		MOV	AH,PRINTBUF
 15500		INT	21H
 15600		POP	AX
 15700	
 15800	HAVEND:
 15900		ADD	[ALLOC],AX	;Total up allocated clusters
 16000		MOV	SI,AX
 16100		MOV	AX,[BP+2]
 16200		MOV	DX,[BP+4]	;AX:DX now have file length
 16300		PUSH	CX
 16400		MOV	CX,[CLUSSIZ]
 16500		DEC	CX
 16600		ADD	AX,CX
 16700		ADC	DX,0
 16800		INC	CX
 16900	SCALE:
 17000		SHR	CX
 17100		JC	SCALED
 17200		SHR	DX
 17300		RCR	AX
 17400		JP	SCALE
 17500	SCALED:
 17600		DIV	AX,[SECSIZ]
 17700		OR	DX,DX
 17800		JZ	HAVSIZ
 17900		INC	AX
 18000	HAVSIZ:
 18100		CMP	AX,SI		;See if file size corresponds with allocation
 18200		JZ	SIZSET
 18300		XOR	DI,DI
 18400		MOV	CX,[CLUSSIZ]
 18500		CALL	UNSCALE
 18600		MOV	[BP+6],SI
 18700		MOV	[BP+8],DI
 18800		MOV	DX,BP
 18900		SUB	DX,34
 19000		MOV	AH,OPEN
 19100		INT	21H
 19110		OR	AL,AL
 19120		JZ	DISKOK2
 19130		JMP	BADDSK
 19140	DISKOK2:
 19200		MOV	AX,[SECSIZ]
 19300		MOV	[BP-27+14],AX	;Make record size=sector size
 19400		MOV	CX,0
 19500		MOV	AH,BLKWRT
 19600		INT	21H
 19700		MOV	AH,CLOSE	;Write back corrected directory entry
 19800		INT	21H
 19900		MOV	AH,GETMAP
 20000		PUSH	DS
 20100		INT	33		;Make sure FAT dirty bit is still set
 20200		POP	DS
 20300		MOV	DX,BADSIZ
 20400		MOV	AH,PRINTBUF
 20500		INT	21H
 20600		POP	AX
 20700		PUSH	AX
 20800		CALL	PRINTNAM
 20900		MOV	DX,CRLF
 21000		MOV	AH,PRINTBUF
 21100		INT	21H
 21200	SIZSET:
 21300		POP	CX
 21400	SIZSET1:
 21500		ADD	BP,44		;Scan next file
 21600		INC	CX
 21700		CMP	CX,[FILECNT]
 21800		JA	COMPMAP
 21900		JMP	EACHFIL
 22000	; Now compare the allocation map we have made with the FAT. Any
 22100	; clusters not allocated in the map will be released.
 22200	COMPMAP:
 22300		XOR	AX,AX		;Keep count of clusters released
 22400		MOV	BP,MAP
 22500		MOV	SI,2		;First usable cluster number
 22600		MOV	CX,[DSKSIZ]
 22700	RELCLUS:
 22800		TEST	[BP],-1		;Allocated in our map?
 22900		JNZ	NXTCLUS		;If so, skip to next
 23000		CALL	UNPACK
 23100		JZ	NXTCLUS		;If not allocated, skip to next
 23200		XOR	DX,DX
 23300		CALL	PACK		;Change to "Free" status
 23400		INC	AX		;Count clusters released
 23500	NXTCLUS:
 23600		INC	BP
 23700		INC	BP
 23800		INC	SI
 23900		LOOP	RELCLUS
 24000		OR	AX,AX		;Any clusters released?
 24100		JZ	REPORT		;If not, do final report
 24200		MOV	BX,FREED
 24300		CALL	DISPCLUS
 24400	REPORT:
 24500	; Make status report. Include no. of files, total disk space,
 24600	; free space on disk, total memory, and free memory.
 24610		SEG	CS
 24620		MOV	DL,[CURDRV]
 24630		MOV	AH,SETDRV
 24640		INT	21H
 24700		MOV	SI,[FILECNT]
 24800		SUB	SI,[DELCNT]
 24900		XOR	DI,DI
 25000		MOV	BX,NUMFIL
 25100		CALL	DISP32BITS
 25200		MOV	AX,[DSKSIZ]
 25300		MOV	BX,DSKSPC
 25400		CALL	DISPCLUS
 25500		MOV	AX,[DSKSIZ]
 25600		SUB	AX,[ALLOC]
 25700		MOV	BX,FRESPC
 25800		CALL	DISPCLUS
 25900		MOV	AX,[2]
 26000		MOV	DX,16
 26100		MUL	AX,DX
 26200		MOV	SI,AX
 26300		MOV	DI,DX
 26400		MOV	BX,TOTMEM
 26500		CALL	DISP32BITS
 26600		MOV	AX,[2]
 26700		MOV	DX,CS
 26800		SUB	AX,DX
 26900		MOV	DX,16
 27000		MUL	AX,DX
 27100		MOV	SI,AX
 27200		MOV	DI,DX
 27300		MOV	BX,FREMEM
 27400		CALL	DISP32BITS
 27405		CALL	WRTFRC		;Force all writes and handle write
 27410					;protect violation
 27900		INT	20H		;All done
 27902	
 27904	WRTFRC:	;********************************************************
 27906		;	This code forces all writes by performing a disk
 27908		;	reset (function 13). When the attempt to write
 27910		;	the allocation table fails in the case of a write-
 27912		;	protected diskette, this logic determines if the
 27914		;	allocation table had changed and if no changes were
 27916		;	made a normal termination will be forced
 27918		;*********************************************************
 27919		MOV	AX,DS
 27920		PUSH	DS		;Must first intercept INT 24H
 27921		MOV	ES,AX
 27922		XOR	AX,AX
 27924		MOV	DS,AX
 27926		MOV	SI,90H
 27928		MOV	DI,INT24	;will move vector to local address
 27930		MOV	CX,2
 27931		CLD			;So move will increment
 27932		REP
 27934		MOVW			;Vector now locally stored
 27936		MOV	AL,24H		;
 27938		MOV	AH,37
 27940		MOV	DX,WRTPRT	;
 27942		POP	DS		;Get local segment
 27944		INT	21H		;Interrupt vector now set
 27946		MOV	AH,13
 27948		INT	21H
 27953		PUSH	ES		;Will now reset INT 24H vector
 27955		XOR	AX,AX
 27957		MOV	ES,AX
 27959		CLD
 27961		MOV	DI,90H
 27963		MOV	SI,INT24
 27965		MOV	CX,2
 27967		REP
 27969		MOVW
 27971		POP	ES
 27973		RET
 27974	
 27976	WRTPRT:	;*********************************************************
 27978		;	This logic is designed to handle the case where
 27980		;	CHKDSK found no problems and upon rewriting the
 27982		;	allocation table (by the DOS) the disk was write-
 27984		;	protected and an error thus occured. With no problems
 27986		;	this code will cause normal termination, otherwise
 27987		;	normal error handling will occur.
 27988		;*********************************************************
 27990		EI		;Run with interrupts live
 27992		AND	DI,0FFH		;See if write-protect
 27994		JNZ	WRT100		;Do normal error handling
 27996		CMP	AH,3		;File allocation write?
 27998		JNZ	WRT100		;If not do normal handling
 27999		SEG	CS
 28000		CMP	[WRKDRV],AL	;Correct drive?
 28002		JNZ	WRT100		;
 28003		SEG	CS
 28004		CMP	B,[CHGCLS],1	;Legitimate change?
 28006		JZ	WRT100		;If so do normal handling
 28007		XOR	AL,AL		;Ignore the error
 28008		IRET
 28009	WRT100:	SEG	CS
 28010		JMP	L,[INT24]	;Normal error handling
 28012	
 28014	
 28015	
 28100	UNPACK:
 28200		MOV	DI,SI
 28300		SHR	DI
 28400		ADD	DI,SI
 28500		SEG	ES
 28600		MOV	DI,[DI+BX]
 28700		TEST	SI,1
 28800		JZ	HAVCLUS
 28900		SHR	DI
 29000		SHR	DI
 29100		SHR	DI
 29200		SHR	DI
 29300	HAVCLUS:
 29400		AND	DI,0FFFH
 29500		RET
 29600	
 29700	PACK:
 29705	;*************************************************************
 29710	;	ES:BX	POINTER TO THE BASE OF THE ALLOCATION TABLE
 29715	;	SI	CLUSTER NUMBER TO BE PACKED
 29720	;	DX	POINTER TO BE PLACED IN CLUSTER (SI)
 29725	;*************************************************************
 29730		MOV	B,[CHGCLS],1	;INDICATE CLUSTER CHANGED
 29800		PUSH	SI
 29900		MOV	DI,SI
 30000		SHR	SI
 30100		ADD	SI,BX
 30200		ADD	SI,DI
 30300		SHR	DI
 30400		SEG	ES
 30500		MOV	DI,[SI]
 30600		JNC	ALIGNED
 30700		SHL	DX
 30800		SHL	DX
 30900		SHL	DX
 31000		SHL	DX
 31100		AND	DI,0FH
 31200		JP	PACKIN
 31300	ALIGNED:
 31400		AND	DI,0F000H
 31500	PACKIN:
 31600		OR	DI,DX
 31700		SEG	ES
 31800		MOV	[SI],DI
 31900		POP	SI
 32000		RET
 32100	
 32200	UNSCALE:
 32300		SHR	CX
 32400		JC	RET
 32500		SHL	SI
 32600		RCL	DI
 32700		JP	UNSCALE
 32800	
 32900	DISPCLUS:
 33000		MUL	AX,[SECSIZ]
 33100		MOV	CX,[CLUSSIZ]
 33200		MOV	SI,AX
 33300		MOV	DI,DX
 33400		CALL	UNSCALE
 33500	DISP32BITS:
 33600		PUSH	BX
 33700		XOR	AX,AX
 33800		MOV	BX,AX
 33900		MOV	BP,AX
 34000		MOV	CX,32
 34100	CONVLP:
 34200		SHL	SI
 34300		RCL	DI
 34400		XCHG	AX,BP
 34500		CALL	CONVWRD
 34600		XCHG	AX,BP
 34700		XCHG	AX,BX
 34800		CALL	CONVWRD
 34900		XCHG	AX,BX
 35000		ADC	AL,0
 35100		LOOP	CONVLP
 35200	; Conversion complete. Print 10-digit number with 2 leading blanks.
 35300		MOV	CX,1B10H
 35400		CALL	OUTWORD
 35500		MOV	AX,BX
 35600		CALL	OUTWORD
 35700		MOV	AX,BP
 35800		CALL	OUTWORD
 35900		POP	DX
 36000		MOV	AH,PRINTBUF
 36100		INT	21H
 36200		RET
 36300	
 36400	OUTWORD:
 36500		PUSH	AX
 36600		MOV	DL,AH
 36700		CALL	OUTBYTE
 36800		POP	DX
 36900	OUTBYTE:
 37000		MOV	DH,DL
 37100		SHR	DL
 37200		SHR	DL
 37300		SHR	DL
 37400		SHR	DL
 37500		CALL	DIGIT
 37600		MOV	DL,DH
 37700	DIGIT:
 37800		AND	DL,0FH
 37900		JZ	BLANKZER
 38000		MOV	CL,0
 38100	BLANKZER:
 38200		DEC	CH
 38300		AND	CL,CH
 38400		OR	DL,30H
 38500		SUB	DL,CL
 38600		MOV	AH,OUTCH
 38700		INT	21H
 38800		RET
 38900	
 39000	CONVWRD:
 39100		ADC	AL,AL
 39200		DAA
 39300		XCHG	AL,AH
 39400		ADC	AL,AL
 39500		DAA
 39600		XCHG	AL,AH
 39700		RET
 39800	
 39900	PRINTNAM:
 39910		PUSH	CX
 40000		DEC	AX
 40100		MOV	CX,44
 40200		MUL	AX,CX
 40300		MOV	SI,AX
 40400		ADD	SI,[NAMTAB]
 40500		ADD	SI,8
 40600		MOV	CX,8
 40700		MOV	AH,OUTCH
 40800		CALL	PRINTCNT
 40900		MOV	DL," "
 41000		INT	21H
 41100		MOV	CL,3
 41110		CALL	PRINTCNT
 41120		POP	CX
 41130		RET
 41140	
 41200	PRINTCNT:
 41300		LODB
 41400		MOV	DL,AL
 41500		INT	21H
 41700		LOOP	PRINTCNT
 41800		RET
 41900	
 41950	ALLFILE:DB	-1,0,0,0,0,0,6	;Extended FCB
 42000		DB	0,"???????????"
 42100		DS	25
 42200	
 42300	FILE2:	DB	"  and  $"
 42305	BADDRV:	DB	"Invalid drive specification$"
 42400	BADCLUS:DB	"Allocation error for file $"
 42500	BADDIR:	DB	"Directory error-file :    $"
 42600	LINKED:	DB	"Files cross-linked: "
 42605		DB	13,10
 42610		DB	"     $"
 42700	BADSIZ:	DB	"File size error for file  $"
 42705	DIRBAD:	DB	"Diskette not initialized $"
 42800	FREED:	DB	" bytes disk space freed",13,10,13,10,"$"
 42900	NUMFIL:	DB	" disk files",13,10,"$"
 43000	DSKSPC:	DB	" bytes total disk space",13,10,"$"
 43100	FRESPC:	DB	" bytes remain available",13,10,13,10,"$"
 43200	TOTMEM:	DB	" bytes total memory",13,10,"$"
 43300	FREMEM:	DB	" bytes free"
 43400	CRLF:	DB	13,10,"$"
 43500	
 43600	DSKSIZ:	DS	2
 43700	SECSIZ:	DS	2
 43800	CLUSSIZ:DS	2
 43805	CHGCLS:	DB	0		;IF RESET TO 1-ALLOCATION TABLE UPDATED
 43810	WRKDRV:	DB	0
 43815	INT24:	DS	4
 43900	FILECNT:DS	2
 44000	NAMTAB:	DS	2
 44100	ALLOC:	DS	2
 44200	MAXCLUS:DS	2
 44300	DELCNT:	DS	2
 44400	CURDRV:	DS	1
 44405		DS	100H
 44410	STACK:
 44500	
 44600	MAP:
@@ -0,0 +1,23 @@
 	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
@@ -0,0 +1,560 @@
 ; CHKDSK	Version 1.0	03/10/81
 ; Verifies and repairs 86-DOS disk directory.
 SETDRV:	EQU	14
 GETDRV:	EQU	25
 GETMAP:	EQU	27
 OPEN:	EQU	15
 CLOSE:	EQU	16
 DELETE:	EQU	19
 SETDMA:	EQU	26
 SRCHFST:EQU	17
 SRCHNXT:EQU	18
 OUTCH:	EQU	2
 BLKWRT:	EQU	40
 PRINTBUF:EQU	9
 	ORG	100H
 	PUT	100H
 CHKDSK:
 	MOV	SP,STACK
 	MOV	AH,GETDRV
 	INT	21H
 	MOV	[CURDRV],AL
 	MOV	DL,[5CH]
 	OR	DL,DL
 	JZ	DRVSET
 	MOV	AH,SETDRV
 	DEC	DL
 	INT	21H
 	CMP	AL,DL
 	JA	DRVSET
 	MOV	DX,BADDRV
 ERROR:
 	MOV	AH,PRINTBUF
 	INT	33
 	INT	32
 BADDSK:
 	MOV	AX,CS
 	MOV	DS,AX
 	MOV	AH,SETDRV
 	MOV	DL,[CURDRV]
 	INT	33
 	MOV	DX,DIRBAD
 	JP	ERROR
 DRVSET:
 	MOV	B,[WRKDRV],DL	;Save drive indicator
 	MOV	AH,GETMAP
 	INT	21H
 	CMP	B,[BX],0FEH	;Check for initialized disk
 	JNE	BADDSK
 	PUSH	DS
 	PUSH	ES
 	POP	DS
 	MOV	[DSKSIZ],DX	;Number of allocation units
 	MOV	[SECSIZ],CX	;Size of physical sector
 	MOV	AH,0
 	MOV	[CLUSSIZ],AX	;Sectors per cluster
 	MOV	CX,DX
 	MOV	DI,MAP
 	XOR	AX,AX
 	REP
 	STOW			;Zero out allocation map
 	MOV	CX,AX
 	MOV	[ALLOC],AX	;Count of allocation units used
 	MOV	[FILECNT],AX	;Number of files found
 	MOV	[DELCNT],AX	;Number of files deleted due to error
 	MOV	BP,DI
 	MOV	[NAMTAB],BP	;First address of file list
 	MOV	DX,DI
 	MOV	AH,SETDMA
 	INT	21H
 	MOV	AH,SRCHFST
 	MOV	DX,ALLFILE
 	INT	21H
 	INC	AL
 	POP	ES		;ES:BX point to FAT
 	JNZ	GETFILES
 	JMP	COMPMAP
 GETFILES:
 	INC	CX		;Count number of files
 	ADD	DI,44		;Separate in file in list by 44 bytes
 	MOV	DX,DI
 	MOV	AH,SETDMA
 	INT	21H
 	MOV	AH,SRCHNXT
 	MOV	DX,ALLFILE
 	INT	21H
 	INC	AL
 	JNZ	GETFILES	;Loop until all files are in list
 	MOV	[FILECNT],CX
 	MOV	CX,1		;File number (position in list)
 	MOV	DX,[DSKSIZ]
 	INC	DX		;Maximum cluster number
 	MOV	[MAXCLUS],DX
 	ADD	BP,34		;Point to "first cluster" entry
 EACHFIL:
 	XOR	AX,AX		;No. of clusters in file
 	MOV	SI,[BP]		;First cluster of file
 	CMP	SI,[MAXCLUS]	;Make sure it's legal
 	MOV	DI,BADDIR
 	JA	BADFIRST
 	OR	SI,SI		;Check for zero-length file
 	JZ	HAVENDJ
 SCANFAT:
 	MOV	DI,CX
 	SHL	SI
 	XCHG	DI,[SI+MAP-4]	;Xchange current map entry with file no.
 	SHR	SI
 	OR	DI,DI		;Should be zero for unallocated cluster
 	JNZ	CROSSLINK
 	INC	AX		;Count cluster as part of this file
 	CALL	UNPACK
 	JZ	FORCEND		;Make sure cluster knows it's allocated
 	CMP	DI,0FF8H	;Bigger than this means End of File
 HAVENDJ:JAE	HAVEND
 	CMP	DI,[MAXCLUS]	;Make sure it's a legal value
 	JA	FORCEND
 	MOV	SI,DI
 	JP	SCANFAT		;Visit each cluster allocated to file
 BADFIRST:
 	PUSH	AX		;Because FILERR will pop it later
 	MOV	AX,CX
 	MOV	DX,44
 	DEC	AX
 	MUL	AX,DX		;Get position in file name table
 	MOV	DX,AX
 	ADD	DX,[NAMTAB]
 	MOV	AH,DELETE
 	INT	21H
 	OR	AL,AL		;SEE IF WE HAVE A VALID DIRECTORY
 	JZ	DISKOK
 	JMP	BADDSK
 DISKOK:
 	INC	[DELCNT]	;Count one deleted file
 	MOV	DX,BADDIR
 	JP	FILERR
 CROSSLINK:
 	MOV	DX,LINKED
 	PUSH	AX
 	MOV	AH,PRINTBUF
 	INT	21H
 	MOV	AX,DI
 	CALL	PRINTNAM
 	MOV	DX,FILE2
 	MOV	AH,PRINTBUF
 	INT	33
 	MOV	AX,CX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	33
 	POP	AX
 	ADD	[ALLOC],AX
 	JMP	SIZSET1
 FORCEND:
 ; Come here if a cluster allocated to a file contained an illegal
 ; link--either a zero (meaning unallocated), or a value larger than
 ; the maximum cluster number, but not End of File. Put an End of File
 ; mark there so the FAT will at least be well-formed.
 	MOV	DX,0FFFH
 	CALL	PACK
 	MOV	DX,BADCLUS
 	PUSH	AX
 FILERR:
 	MOV	AH,PRINTBUF
 	INT	21H
 	MOV	AX,CX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	21H
 	POP	AX
 HAVEND:
 	ADD	[ALLOC],AX	;Total up allocated clusters
 	MOV	SI,AX
 	MOV	AX,[BP+2]
 	MOV	DX,[BP+4]	;AX:DX now have file length
 	PUSH	CX
 	MOV	CX,[CLUSSIZ]
 	DEC	CX
 	ADD	AX,CX
 	ADC	DX,0
 	INC	CX
 SCALE:
 	SHR	CX
 	JC	SCALED
 	SHR	DX
 	RCR	AX
 	JP	SCALE
 SCALED:
 	DIV	AX,[SECSIZ]
 	OR	DX,DX
 	JZ	HAVSIZ
 	INC	AX
 HAVSIZ:
 	CMP	AX,SI		;See if file size corresponds with allocation
 	JZ	SIZSET
 	XOR	DI,DI
 	MOV	CX,[CLUSSIZ]
 	CALL	UNSCALE
 	MOV	[BP+6],SI
 	MOV	[BP+8],DI
 	MOV	DX,BP
 	SUB	DX,34
 	MOV	AH,OPEN
 	INT	21H
 	OR	AL,AL
 	JZ	DISKOK2
 	JMP	BADDSK
 DISKOK2:
 	MOV	AX,[SECSIZ]
 	MOV	[BP-27+14],AX	;Make record size=sector size
 	MOV	CX,0
 	MOV	AH,BLKWRT
 	INT	21H
 	MOV	AH,CLOSE	;Write back corrected directory entry
 	INT	21H
 	MOV	AH,GETMAP
 	PUSH	DS
 	INT	33		;Make sure FAT dirty bit is still set
 	POP	DS
 	MOV	DX,BADSIZ
 	MOV	AH,PRINTBUF
 	INT	21H
 	POP	AX
 	PUSH	AX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	21H
 SIZSET:
 	POP	CX
 SIZSET1:
 	ADD	BP,44		;Scan next file
 	INC	CX
 	CMP	CX,[FILECNT]
 	JA	COMPMAP
 	JMP	EACHFIL
 ; Now compare the allocation map we have made with the FAT. Any
 ; clusters not allocated in the map will be released.
 COMPMAP:
 	XOR	AX,AX		;Keep count of clusters released
 	MOV	BP,MAP
 	MOV	SI,2		;First usable cluster number
 	MOV	CX,[DSKSIZ]
 RELCLUS:
 	TEST	[BP],-1		;Allocated in our map?
 	JNZ	NXTCLUS		;If so, skip to next
 	CALL	UNPACK
 	JZ	NXTCLUS		;If not allocated, skip to next
 	XOR	DX,DX
 	CALL	PACK		;Change to "Free" status
 	INC	AX		;Count clusters released
 NXTCLUS:
 	INC	BP
 	INC	BP
 	INC	SI
 	LOOP	RELCLUS
 	OR	AX,AX		;Any clusters released?
 	JZ	REPORT		;If not, do final report
 	MOV	BX,FREED
 	CALL	DISPCLUS
 REPORT:
 ; Make status report. Include no. of files, total disk space,
 ; free space on disk, total memory, and free memory.
 	SEG	CS
 	MOV	DL,[CURDRV]
 	MOV	AH,SETDRV
 	INT	21H
 	MOV	SI,[FILECNT]
 	SUB	SI,[DELCNT]
 	XOR	DI,DI
 	MOV	BX,NUMFIL
 	CALL	DISP32BITS
 	MOV	AX,[DSKSIZ]
 	MOV	BX,DSKSPC
 	CALL	DISPCLUS
 	MOV	AX,[DSKSIZ]
 	SUB	AX,[ALLOC]
 	MOV	BX,FRESPC
 	CALL	DISPCLUS
 	MOV	AX,[2]
 	MOV	DX,16
 	MUL	AX,DX
 	MOV	SI,AX
 	MOV	DI,DX
 	MOV	BX,TOTMEM
 	CALL	DISP32BITS
 	MOV	AX,[2]
 	MOV	DX,CS
 	SUB	AX,DX
 	MOV	DX,16
 	MUL	AX,DX
 	MOV	SI,AX
 	MOV	DI,DX
 	MOV	BX,FREMEM
 	CALL	DISP32BITS
 	CALL	WRTFRC		;Force all writes and handle write
 				;protect violation
 	INT	20H		;All done
 WRTFRC:	;********************************************************
 	;	This code forces all writes by performing a disk
 	;	reset (function 13). When the attempt to write
 	;	the allocation table fails in the case of a write-
 	;	protected diskette, this logic determines if the
 	;	allocation table had changed and if no changes were
 	;	made a normal termination will be forced
 	;*********************************************************
 	MOV	AX,DS
 	PUSH	DS		;Must first intercept INT 24H
 	MOV	ES,AX
 	XOR	AX,AX
 	MOV	DS,AX
 	MOV	SI,90H
 	MOV	DI,INT24	;will move vector to local address
 	MOV	CX,2
 	CLD			;So move will increment
 	REP
 	MOVW			;Vector now locally stored
 	MOV	AL,24H		;
 	MOV	AH,37
 	MOV	DX,WRTPRT	;
 	POP	DS		;Get local segment
 	INT	21H		;Interrupt vector now set
 	MOV	AH,13
 	INT	21H
 	PUSH	ES		;Will now reset INT 24H vector
 	XOR	AX,AX
 	MOV	ES,AX
 	CLD
 	MOV	DI,90H
 	MOV	SI,INT24
 	MOV	CX,2
 	REP
 	MOVW
 	POP	ES
 	RET
 WRTPRT:	;*********************************************************
 	;	This logic is designed to handle the case where
 	;	CHKDSK found no problems and upon rewriting the
 	;	allocation table (by the DOS) the disk was write-
 	;	protected and an error thus occured. With no problems
 	;	this code will cause normal termination, otherwise
 	;	normal error handling will occur.
 	;*********************************************************
 	EI		;Run with interrupts live
 	AND	DI,0FFH		;See if write-protect
 	JNZ	WRT100		;Do normal error handling
 	CMP	AH,3		;File allocation write?
 	JNZ	WRT100		;If not do normal handling
 	SEG	CS
 	CMP	[WRKDRV],AL	;Correct drive?
 	JNZ	WRT100		;
 	SEG	CS
 	CMP	B,[CHGCLS],1	;Legitimate change?
 	JZ	WRT100		;If so do normal handling
 	XOR	AL,AL		;Ignore the error
 	IRET
 WRT100:	SEG	CS
 	JMP	L,[INT24]	;Normal error handling
 UNPACK:
 	MOV	DI,SI
 	SHR	DI
 	ADD	DI,SI
 	SEG	ES
 	MOV	DI,[DI+BX]
 	TEST	SI,1
 	JZ	HAVCLUS
 	SHR	DI
 	SHR	DI
 	SHR	DI
 	SHR	DI
 HAVCLUS:
 	AND	DI,0FFFH
 	RET
 PACK:
 ;*************************************************************
 ;	ES:BX	POINTER TO THE BASE OF THE ALLOCATION TABLE
 ;	SI	CLUSTER NUMBER TO BE PACKED
 ;	DX	POINTER TO BE PLACED IN CLUSTER (SI)
 ;*************************************************************
 	MOV	B,[CHGCLS],1	;INDICATE CLUSTER CHANGED
 	PUSH	SI
 	MOV	DI,SI
 	SHR	SI
 	ADD	SI,BX
 	ADD	SI,DI
 	SHR	DI
 	SEG	ES
 	MOV	DI,[SI]
 	JNC	ALIGNED
 	SHL	DX
 	SHL	DX
 	SHL	DX
 	SHL	DX
 	AND	DI,0FH
 	JP	PACKIN
 ALIGNED:
 	AND	DI,0F000H
 PACKIN:
 	OR	DI,DX
 	SEG	ES
 	MOV	[SI],DI
 	POP	SI
 	RET
 UNSCALE:
 	SHR	CX
 	JC	RET
 	SHL	SI
 	RCL	DI
 	JP	UNSCALE
 DISPCLUS:
 	MUL	AX,[SECSIZ]
 	MOV	CX,[CLUSSIZ]
 	MOV	SI,AX
 	MOV	DI,DX
 	CALL	UNSCALE
 DISP32BITS:
 	PUSH	BX
 	XOR	AX,AX
 	MOV	BX,AX
 	MOV	BP,AX
 	MOV	CX,32
 CONVLP:
 	SHL	SI
 	RCL	DI
 	XCHG	AX,BP
 	CALL	CONVWRD
 	XCHG	AX,BP
 	XCHG	AX,BX
 	CALL	CONVWRD
 	XCHG	AX,BX
 	ADC	AL,0
 	LOOP	CONVLP
 ; Conversion complete. Print 10-digit number with 2 leading blanks.
 	MOV	CX,1B10H
 	CALL	OUTWORD
 	MOV	AX,BX
 	CALL	OUTWORD
 	MOV	AX,BP
 	CALL	OUTWORD
 	POP	DX
 	MOV	AH,PRINTBUF
 	INT	21H
 	RET
 OUTWORD:
 	PUSH	AX
 	MOV	DL,AH
 	CALL	OUTBYTE
 	POP	DX
 OUTBYTE:
 	MOV	DH,DL
 	SHR	DL
 	SHR	DL
 	SHR	DL
 	SHR	DL
 	CALL	DIGIT
 	MOV	DL,DH
 DIGIT:
 	AND	DL,0FH
 	JZ	BLANKZER
 	MOV	CL,0
 BLANKZER:
 	DEC	CH
 	AND	CL,CH
 	OR	DL,30H
 	SUB	DL,CL
 	MOV	AH,OUTCH
 	INT	21H
 	RET
 CONVWRD:
 	ADC	AL,AL
 	DAA
 	XCHG	AL,AH
 	ADC	AL,AL
 	DAA
 	XCHG	AL,AH
 	RET
 PRINTNAM:
 	PUSH	CX
 	DEC	AX
 	MOV	CX,44
 	MUL	AX,CX
 	MOV	SI,AX
 	ADD	SI,[NAMTAB]
 	ADD	SI,8
 	MOV	CX,8
 	MOV	AH,OUTCH
 	CALL	PRINTCNT
 	MOV	DL," "
 	INT	21H
 	MOV	CL,3
 	CALL	PRINTCNT
 	POP	CX
 	RET
 PRINTCNT:
 	LODB
 	MOV	DL,AL
 	INT	21H
 	LOOP	PRINTCNT
 	RET
 ALLFILE:DB	-1,0,0,0,0,0,6	;Extended FCB
 	DB	0,"???????????"
 	DS	25
 FILE2:	DB	"  and  $"
 BADDRV:	DB	"Invalid drive specification$"
 BADCLUS:DB	"Allocation error for file $"
 BADDIR:	DB	"Directory error-file :    $"
 LINKED:	DB	"Files cross-linked: "
 	DB	13,10
 	DB	"     $"
 BADSIZ:	DB	"File size error for file  $"
 DIRBAD:	DB	"Diskette not initialized $"
 FREED:	DB	" bytes disk space freed",13,10,13,10,"$"
 NUMFIL:	DB	" disk files",13,10,"$"
 DSKSPC:	DB	" bytes total disk space",13,10,"$"
 FRESPC:	DB	" bytes remain available",13,10,13,10,"$"
 TOTMEM:	DB	" bytes total memory",13,10,"$"
 FREMEM:	DB	" bytes free"
 CRLF:	DB	13,10,"$"
 DSKSIZ:	DS	2
 SECSIZ:	DS	2
 CLUSSIZ:DS	2
 CHGCLS:	DB	0		;IF RESET TO 1-ALLOCATION TABLE UPDATED
 WRKDRV:	DB	0
 INT24:	DS	4
 FILECNT:DS	2
 NAMTAB:	DS	2
 ALLOC:	DS	2
 MAXCLUS:DS	2
 DELCNT:	DS	2
 CURDRV:	DS	1
 	DS	100H
 STACK:
 MAP:
@@ -0,0 +1,611 @@
 ; CHKDSK	Version 1.0	03/10/81
 ; Verifies and repairs 86-DOS disk directory.
 SETDRV:	EQU	14
 GETDRV:	EQU	25
 GETMAP:	EQU	27
 OPEN:	EQU	15
 CLOSE:	EQU	16
 DELETE:	EQU	19
 SETDMA:	EQU	26
 SRCHFST:EQU	17
 SRCHNXT:EQU	18
 OUTCH:	EQU	2
 BLKWRT:	EQU	40
 PRINTBUF:EQU	9
 	ORG	100H
 	PUT	100H
 CHKDSK:
 	MOV	SP,STACK
 	OR	AL,AL		;SEE IF INVALID DRIVE SPECIFIED
 	JNZ	DRVERR		;IF SO JUST EXIT
 	CMP	B,[5DH],20H	;MAKE SURE TYPED CORRECTLY
 	JNZ	PRMERR		;IF NOT PARAMETER ERROR
 	MOV	AH,GETDRV
 	INT	21H
 	MOV	[CURDRV],AL
 	MOV	DL,[5CH]
 	OR	DL,DL
 	JZ	DRVMOV
 	MOV	AH,SETDRV
 	DEC	DL
 	INT	21H
 	CMP	AL,DL
 	JA	DRVSET
 DRVERR:	MOV	DX,BADDRV
 ERROR:
 	MOV	AH,PRINTBUF
 	INT	33
 	INT	32
 PRMERR:	MOV	DX,INVPRM	;Invalid parameter
 	JP	ERROR
 BADDSK:
 	MOV	AX,CS
 	MOV	DS,AX
 	MOV	AH,SETDRV
 	MOV	DL,[CURDRV]
 	INT	33
 	MOV	DX,DIRBAD
 	JP	ERROR
 DRVMOV:	MOV	DL,AL		;Correct drive designator
 DRVSET:
 	MOV	B,[WRKDRV],DL	;Save drive indicator
 	INC	DL		;FOR FCB SET
 	MOV	B,[ALLDRV],DL	;FCB ok now
 	DEC	DL
 	CALL	DRVXCG		;Change drives and do map read
 	CMP	B,[BX],0FEH	;Check for initialized disk
 	JNE	BADDSK
 	PUSH	DS
 	PUSH	ES
 	POP	DS
 	MOV	[DSKSIZ],DX	;Number of allocation units
 	MOV	[SECSIZ],CX	;Size of physical sector
 	MOV	AH,0
 	MOV	[CLUSSIZ],AX	;Sectors per cluster
 	MOV	CX,DX
 	MOV	DI,MAP
 	XOR	AX,AX
 	REP
 	STOW			;Zero out allocation map
 	MOV	CX,AX
 	MOV	[ALLOC],AX	;Count of allocation units used
 	MOV	[FILECNT],AX	;Number of files found
 	MOV	[DELCNT],AX	;Number of files deleted due to error
 	MOV	BP,DI
 	MOV	[NAMTAB],BP	;First address of file list
 	MOV	DX,DI
 	MOV	AH,SETDMA
 	INT	21H
 	MOV	AH,SRCHFST
 	MOV	DX,ALLFILE
 	INT	21H
 	INC	AL
 	POP	ES		;ES:BX point to FAT
 	JNZ	GETFILES
 	JMP	COMPMAP
 GETFILES:
 	INC	CX		;Count number of files
 	ADD	DI,44		;Separate in file in list by 44 bytes
 	MOV	DX,DI
 	MOV	AH,SETDMA
 	INT	21H
 	MOV	AH,SRCHNXT
 	MOV	DX,ALLFILE
 	INT	21H
 	INC	AL
 	JNZ	GETFILES	;Loop until all files are in list
 	MOV	[FILECNT],CX
 	MOV	CX,1		;File number (position in list)
 	MOV	DX,[DSKSIZ]
 	INC	DX		;Maximum cluster number
 	MOV	[MAXCLUS],DX
 	ADD	BP,34		;Point to "first cluster" entry
 EACHFIL:
 	XOR	AX,AX		;No. of clusters in file
 	MOV	SI,[BP]		;First cluster of file
 	CMP	SI,[MAXCLUS]	;Make sure it's legal
 	MOV	DI,BADDIR
 	JA	BADFIRST
 	OR	SI,SI		;Check for zero-length file
 	JZ	HAVENDJ
 SCANFAT:
 	MOV	DI,CX
 	SHL	SI
 	XCHG	DI,[SI+MAP-4]	;Xchange current map entry with file no.
 	SHR	SI
 	OR	DI,DI		;Should be zero for unallocated cluster
 	JNZ	CROSSLINK
 	INC	AX		;Count cluster as part of this file
 	CALL	UNPACK
 	JZ	FORCEND		;Make sure cluster knows it's allocated
 	CMP	DI,0FF8H	;Bigger than this means End of File
 HAVENDJ:JAE	HAVEND
 	CMP	DI,[MAXCLUS]	;Make sure it's a legal value
 	JA	FORCEND
 	MOV	SI,DI
 	JP	SCANFAT		;Visit each cluster allocated to file
 BADFIRST:
 	PUSH	AX		;Because FILERR will pop it later
 	MOV	[BP+2],AX	;AX is zero
 	MOV	[BP+4],AX	;Set size to zero so we won't change it
 	MOV	AX,CX
 	MOV	DX,44
 	DEC	AX
 	MUL	AX,DX		;Get position in file name table
 	MOV	DX,AX
 	ADD	DX,[NAMTAB]
 	MOV	AH,DELETE
 	INT	21H
 	PUSH	DS
 	PUSH	CX
 	PUSH	AX
 	CALL	DRVXCG		;Reset dirty bit to rewrite FAT
 	POP	AX
 	POP	CX
 	POP	DS
 	OR	AL,AL		;SEE IF WE HAVE A VALID DIRECTORY
 	JZ	DISKOK
 	JMP	BADDSK
 DISKOK:
 	INC	[DELCNT]	;Count one deleted file
 	MOV	DX,BADDIR
 	JP	FILERR
 CROSSLINK:
 	MOV	DX,LINKED
 	PUSH	AX
 	MOV	AH,PRINTBUF
 	INT	21H
 	MOV	AX,DI
 	CALL	PRINTNAM
 	MOV	DX,FILE2
 	MOV	AH,PRINTBUF
 	INT	33
 	MOV	AX,CX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	33
 	POP	AX
 	ADD	[ALLOC],AX
 	JMP	SIZSET1
 FORCEND:
 ; Come here if a cluster allocated to a file contained an illegal
 ; link--either a zero (meaning unallocated), or a value larger than
 ; the maximum cluster number, but not End of File. Put an End of File
 ; mark there so the FAT will at least be well-formed.
 	MOV	DX,0FFFH
 	CALL	PACK
 	MOV	DX,BADCLUS
 	PUSH	AX
 FILERR:
 	MOV	AH,PRINTBUF
 	INT	21H
 	MOV	AX,CX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	21H
 	POP	AX
 HAVEND:
 	ADD	[ALLOC],AX	;Total up allocated clusters
 	MOV	SI,AX
 	MOV	AX,[BP+2]
 	MOV	DX,[BP+4]	;AX:DX now have file length
 	PUSH	CX
 	MOV	CX,[CLUSSIZ]
 	DEC	CX
 	ADD	AX,CX
 	ADC	DX,0
 	INC	CX
 SCALE:
 	SHR	CX
 	JC	SCALED
 	SHR	DX
 	RCR	AX
 	JP	SCALE
 SCALED:
 	DIV	AX,[SECSIZ]
 	OR	DX,DX
 	JZ	HAVSIZ
 	INC	AX
 HAVSIZ:
 	CMP	AX,SI		;See if file size corresponds with allocation
 	JZ	SIZSET
 	XOR	DI,DI
 	MOV	CX,[CLUSSIZ]
 	CALL	UNSCALE
 	MOV	[BP+6],SI
 	MOV	[BP+8],DI
 	MOV	DX,BP
 	SUB	DX,34
 	MOV	AH,OPEN
 	INT	21H
 	OR	AL,AL
 	JZ	DISKOK2
 	JMP	BADDSK
 DISKOK2:
 	MOV	AX,[SECSIZ]
 	MOV	[BP-27+14],AX	;Make record size=sector size
 	MOV	CX,0
 	MOV	AH,BLKWRT
 	INT	21H
 	MOV	AH,CLOSE	;Write back corrected directory entry
 	INT	21H
 	PUSH	DS
 	CALL	DRVXCG		;Change the drives and get the map
 	POP	DS
 	MOV	DX,BADSIZ
 	MOV	AH,PRINTBUF
 	INT	21H
 	POP	AX
 	PUSH	AX
 	CALL	PRINTNAM
 	MOV	DX,CRLF
 	MOV	AH,PRINTBUF
 	INT	21H
 SIZSET:
 	POP	CX
 SIZSET1:
 	ADD	BP,44		;Scan next file
 	INC	CX
 	CMP	CX,[FILECNT]
 	JA	COMPMAP
 	JMP	EACHFIL
 ; Now compare the allocation map we have made with the FAT. Any
 ; clusters not allocated in the map will be released.
 COMPMAP:
 	XOR	AX,AX		;Keep count of clusters released
 	MOV	BP,MAP
 	MOV	SI,2		;First usable cluster number
 	MOV	CX,[DSKSIZ]
 RELCLUS:
 	TEST	[BP],-1		;Allocated in our map?
 	JNZ	NXTCLUS		;If so, skip to next
 	CALL	UNPACK
 	JZ	NXTCLUS		;If not allocated, skip to next
 	XOR	DX,DX
 	CALL	PACK		;Change to "Free" status
 	INC	AX		;Count clusters released
 NXTCLUS:
 	INC	BP
 	INC	BP
 	INC	SI
 	LOOP	RELCLUS
 	OR	AX,AX		;Any clusters released?
 	JZ	REPORT		;If not, do final report
 	MOV	BX,FREED
 	CALL	DISPCLUS
 REPORT:
 ; Make status report. Include no. of files, total disk space,
 ; free space on disk, total memory, and free memory.
 	SEG	CS
 	MOV	DL,[CURDRV]
 	MOV	AH,SETDRV
 	INT	21H
 	MOV	SI,[FILECNT]
 	SUB	SI,[DELCNT]
 	XOR	DI,DI
 	MOV	BX,NUMFIL
 	CALL	DISP32BITS
 	MOV	AX,[DSKSIZ]
 	MOV	BX,DSKSPC
 	CALL	DISPCLUS
 	MOV	AX,[DSKSIZ]
 	SUB	AX,[ALLOC]
 	MOV	BX,FRESPC
 	CALL	DISPCLUS
 	MOV	AX,[2]
 	MOV	DX,16
 	MUL	AX,DX
 	MOV	SI,AX
 	MOV	DI,DX
 	MOV	BX,TOTMEM
 	CALL	DISP32BITS
 	MOV	AX,[2]
 	MOV	DX,CS
 	SUB	AX,DX
 	MOV	DX,16
 	MUL	AX,DX
 	MOV	SI,AX
 	MOV	DI,DX
 	MOV	BX,FREMEM
 	CALL	DISP32BITS
 	CALL	WRTFRC		;Force all writes and handle write
 				;protect violation
 	SEG	CS
 	MOV	B,DL,[CURDRV]	;Get default
 	MOV	AH,SETDRV	;And make it current again
 	INT	21H
 	INT	20H		;All done
 WRTFRC:	;********************************************************
 	;	This code forces all writes by performing a disk
 	;	reset (function 13). When the attempt to write
 	;	the allocation table fails in the case of a write-
 	;	protected diskette, this logic determines if the
 	;	allocation table had changed and if no changes were
 	;	made a normal termination will be forced
 	;*********************************************************
 	MOV	AX,DS
 	PUSH	DS		;Must first intercept INT 24H
 	MOV	ES,AX
 	XOR	AX,AX
 	MOV	DS,AX
 	MOV	SI,90H
 	MOV	DI,INT24	;will move vector to local address
 	MOV	CX,2
 	CLD			;So move will increment
 	REP
 	MOVW			;Vector now locally stored
 	MOV	AL,24H		;
 	MOV	AH,37
 	MOV	DX,WRTPRT	;
 	POP	DS		;Get local segment
 	INT	21H		;Interrupt vector now set
 	MOV	AH,13
 	INT	21H
 	PUSH	ES		;Will now reset INT 24H vector
 	XOR	AX,AX
 	MOV	ES,AX
 	CLD
 	MOV	DI,90H
 	MOV	SI,INT24
 	MOV	CX,2
 	REP
 	MOVW
 	POP	ES
 	RET
 WRTPRT:	;*********************************************************
 	;	This logic is designed to handle the case where
 	;	CHKDSK found no problems and upon rewriting the
 	;	allocation table (by the DOS) the disk was write-
 	;	protected and an error thus occured. With no problems
 	;	this code will cause normal termination, otherwise
 	;	normal error handling will occur.
 	;*********************************************************
 	EI		;Run with interrupts live
 	AND	DI,0FFH		;See if write-protect
 	JNZ	WRT100		;Do normal error handling
 	CMP	AH,3		;File allocation write?
 	JNZ	WRT100		;If not do normal handling
 	SEG	CS
 	CMP	[WRKDRV],AL	;Correct drive?
 	JNZ	WRT100		;
 	SEG	CS
 	CMP	B,[CHGCLS],1	;Legitimate change?
 	JZ	WRT100		;If so do normal handling
 	XOR	AL,AL		;Ignore the error
 	IRET
 WRT100:	SEG	CS
 	MOV	SI,AX		;Save AX
 	PUSH	DX
 	MOV	DL,[CURDRV]	;Fetch current drive
 	MOV	AH,SETDRV
 	INT	33		;Drive now ok
 	POP	DX		;Restore DX
 	MOV	AX,SI		;Restore AX
 	SEG	CS
 	JMP	L,[INT24]	;Do normal recovery
 DRVXCG:
 	;**********************************************
 	;	WILL CHANGE DEFAULT TO WRKDRV READ THE FAT
 	;	AND CHANGE THE DEFAULT BACK TO CURDRV
 	;**********************************************
 	SEG	CS
 	MOV	DL,[WRKDRV]	;Will change the default to this
 	MOV	AH,SETDRV
 	INT	33		;Default now "WRKDRV"
 	MOV	AH,GETMAP
 	INT	33
 	PUSH	DX
 	PUSH	AX
 	SEG	CS
 	MOV	DL,[CURDRV]	;Get current drive
 	MOV	AH,SETDRV
 	INT	33
 	POP	AX
 	POP	DX
 	RET
 UNPACK:
 	MOV	DI,SI
 	SHR	DI
 	ADD	DI,SI
 	SEG	ES
 	MOV	DI,[DI+BX]
 	TEST	SI,1
 	JZ	HAVCLUS
 	SHR	DI
 	SHR	DI
 	SHR	DI
 	SHR	DI
 HAVCLUS:
 	AND	DI,0FFFH
 	RET
 PACK:
 ;*************************************************************
 ;	ES:BX	POINTER TO THE BASE OF THE ALLOCATION TABLE
 ;	SI	CLUSTER NUMBER TO BE PACKED
 ;	DX	POINTER TO BE PLACED IN CLUSTER (SI)
 ;*************************************************************
 	MOV	B,[CHGCLS],1	;INDICATE CLUSTER CHANGED
 	PUSH	SI
 	MOV	DI,SI
 	SHR	SI
 	ADD	SI,BX
 	ADD	SI,DI
 	SHR	DI
 	SEG	ES
 	MOV	DI,[SI]
 	JNC	ALIGNED
 	SHL	DX
 	SHL	DX
 	SHL	DX
 	SHL	DX
 	AND	DI,0FH
 	JP	PACKIN
 ALIGNED:
 	AND	DI,0F000H
 PACKIN:
 	OR	DI,DX
 	SEG	ES
 	MOV	[SI],DI
 	POP	SI
 	RET
 UNSCALE:
 	SHR	CX
 	JC	RET
 	SHL	SI
 	RCL	DI
 	JP	UNSCALE
 DISPCLUS:
 	MUL	AX,[SECSIZ]
 	MOV	CX,[CLUSSIZ]
 	MOV	SI,AX
 	MOV	DI,DX
 	CALL	UNSCALE
 DISP32BITS:
 	PUSH	BX
 	XOR	AX,AX
 	MOV	BX,AX
 	MOV	BP,AX
 	MOV	CX,32
 CONVLP:
 	SHL	SI
 	RCL	DI
 	XCHG	AX,BP
 	CALL	CONVWRD
 	XCHG	AX,BP
 	XCHG	AX,BX
 	CALL	CONVWRD
 	XCHG	AX,BX
 	ADC	AL,0
 	LOOP	CONVLP
 ; Conversion complete. Print 10-digit number with 2 leading blanks.
 	MOV	CX,1B10H
 	CALL	OUTWORD
 	MOV	AX,BX
 	CALL	OUTWORD
 	MOV	AX,BP
 	CALL	OUTWORD
 	POP	DX
 	MOV	AH,PRINTBUF
 	INT	21H
 	RET
 OUTWORD:
 	PUSH	AX
 	MOV	DL,AH
 	CALL	OUTBYTE
 	POP	DX
 OUTBYTE:
 	MOV	DH,DL
 	SHR	DL
 	SHR	DL
 	SHR	DL
 	SHR	DL
 	CALL	DIGIT
 	MOV	DL,DH
 DIGIT:
 	AND	DL,0FH
 	JZ	BLANKZER
 	MOV	CL,0
 BLANKZER:
 	DEC	CH
 	AND	CL,CH
 	OR	DL,30H
 	SUB	DL,CL
 	MOV	AH,OUTCH
 	INT	21H
 	RET
 CONVWRD:
 	ADC	AL,AL
 	DAA
 	XCHG	AL,AH
 	ADC	AL,AL
 	DAA
 	XCHG	AL,AH
 	RET
 PRINTNAM:
 	PUSH	CX
 	DEC	AX
 	MOV	CX,44
 	MUL	AX,CX
 	MOV	SI,AX
 	ADD	SI,[NAMTAB]
 	ADD	SI,8
 	MOV	CX,8
 	MOV	AH,OUTCH
 	CALL	PRINTCNT
 	MOV	DL," "
 	INT	21H
 	MOV	CL,3
 	CALL	PRINTCNT
 	POP	CX
 	RET
 PRINTCNT:
 	LODB
 	MOV	DL,AL
 	INT	21H
 	LOOP	PRINTCNT
 	RET
 ALLFILE:DB	-1,0,0,0,0,0,6	;Extended FCB
 ALLDRV:	DB	0,"???????????"
 	DS	25
 FILE2:	DB	"  and  $"
 BADDRV:	DB	"Invalid drive specification$"
 INVPRM:	DB	"Invalid parameter$"
 BADCLUS:DB	"Allocation error for file $"
 BADDIR:	DB	"Directory error-file :    $"
 LINKED:	DB	"Files cross-linked: "
 	DB	13,10
 	DB	"     $"
 BADSIZ:	DB	"File size error for file  $"
 DIRBAD:	DB	"Diskette not initialized $"
 FREED:	DB	" bytes disk space freed",13,10,13,10,"$"
 NUMFIL:	DB	" disk files",13,10,"$"
 DSKSPC:	DB	" bytes total disk space",13,10,"$"
 FRESPC:	DB	" bytes remain available",13,10,13,10,"$"
 TOTMEM:	DB	" bytes total memory",13,10,"$"
 FREMEM:	DB	" bytes free"
 CRLF:	DB	13,10,"$"
 DSKSIZ:	DS	2
 SECSIZ:	DS	2
 CLUSSIZ:DS	2
 CHGCLS:	DB	0		;IF RESET TO 1-ALLOCATION TABLE UPDATED
 WRKDRV:	DB	0
 INT24:	DS	4
 FILECNT:DS	2
 NAMTAB:	DS	2
 ALLOC:	DS	2
 MAXCLUS:DS	2
 DELCNT:	DS	2
 CURDRV:	DS	1
 	DS	100H
 STACK:
 MAP:
@@ -0,0 +1,110 @@
 # Paterson Listings
 Tim Paterson's DOS listings, containing source code of 86-DOS 1.00 kernel,
 various PC-DOS 1.00 pre-release kernels and utilities, and the Microsoft
 BASIC-86 Compiler runtime library.
 <p align="center">
 <img
 src="https://archive.org/download/paterson_listings/images/paterson_photo.jpg"
 width="50%" align="center">
 </p>
 The DOS-related portions have been transcribed and turned into compilable
 source code.
 ## Downloads and Layout
 - [`1_transcription`](./1_transcription/) ([download](https://github.com/DOS-History/Paterson-Listings/releases/latest/download/paterson_listings_transcription.zip)) -
 transcription of the listings, essentially the raw printer output
 - [`2_printed_files`](./2_printed_files/) ([download](https://github.com/DOS-History/Paterson-Listings/releases/latest/download/paterson_listings_printed_files.zip)) -
 the original files that were printed, extracted from the raw printer output
 above
 - [`3_source_code`](./3_source_code/) ([download](https://github.com/DOS-History/Paterson-Listings/releases/latest/download/paterson_listings_source_code.zip)) -
 compilable source code extracted from the printed files above
 If you just want to browse the source code or compile/assemble it, choose
 [`3_source_code`](./3_source_code/). The original scans, in PDF and PNG
 formats, are available at https://archive.org/details/paterson_listings.
 Further details about these listings, including technical writeups, can be
 found at:
 - https://thebrokenpipe.com/dos/paterson_listings
 - http://cini.classiccmp.org/recoveryblog.htm
 ## Listing Content
 Paterson's stack of DOS listings contains 10 bundles of continuous-feed paper,
 from top to bottom:
 - [Bundle 01](https://archive.org/download/paterson_listings/bundle01.pdf)
 (86 pages):
    - [`MSDOS.LST`](./2_printed_files/bundle_01/MSDOS.LST)
 - [Bundle 02](https://archive.org/download/paterson_listings/bundle02.pdf)
 (62 pages):
    - [`86DOS.A86`](./2_printed_files/bundle_02/86DOS.A86)
    (created: 1981/07/07 17:06:59, printed: 1981/07/08 13:49:52)
 - [Bundle 03](https://archive.org/download/paterson_listings/bundle03.pdf)
 (18 pages):
    - [`EDLIN.DIF`](./2_printed_files/bundle_03/EDLIN.DIF)
    (created: 1981/07/28 14:21:18, printed: 1981/07/28 14:40:48)
    - [`CHKDSK.A86`](./2_printed_files/bundle_03/CHKDSK.A86)
    (created: 1981/07/15 12:19:22, printed: 1981/07/28 14:41:25)
 - [Bundle 04](https://archive.org/download/paterson_listings/bundle04.pdf)
 (58 pages):
    - [`86DOS.ASM`](./2_printed_files/bundle_04/86DOS.ASM)
    (created: 1981/06/15 03:18:51, printed: 1981/06/16 15:17:17)
 - [Bundle 05](https://archive.org/download/paterson_listings/bundle05.pdf)
 (57 pages):
    - [`ASM.PRN`](./2_printed_files/bundle_05/ASM.PRN)
 - [Bundle 06](https://archive.org/download/paterson_listings/bundle06.pdf)
 (71 pages):
    - [`ASM.PRN`](./2_printed_files/bundle_06/ASM.PRN)
 - [Bundle 07](https://archive.org/download/paterson_listings/bundle07.pdf)
 (10 pages):
    - [`CHKDSK.A86`](./2_printed_files/bundle_07/CHKDSK.A86)
    (created: 1981/06/15 04:10:28, printed: 1981/06/16 15:32:54)
 - [Bundle 08](https://archive.org/download/paterson_listings/bundle08.pdf)
 (32 pages):
    - [`86DOS.DIF`](./2_printed_files/bundle_08/86DOS.DIF)
    (created: 1981/06/16 15:11:47, printed: 1981/06/16 15:13:47)
 - [Bundle 09](https://archive.org/download/paterson_listings/bundle09.pdf)
 (459 pages):
    - `LIBLST.LOG`
    (created: 1981/11/13 01:10:16, printed: 1981/11/13 01:17:42)
    - `BASLIB.PRT`
    (created: 1981/11/13 01:09:35, printed: 1981/11/13 01:19:29)
 - [Bundle 10](https://archive.org/download/paterson_listings/bundle10.pdf)
 (20 pages):
    - `PAINT.ASM`
    (created: 1982/01/06 22:20:26, printed: 1982/02/06 20:58:03)
    - `CIRCLE.ASM`
    (created: 1982/02/04 11:51:32, printed: 1982/02/06 20:58:44)
 Bundles 9 and 10 have not yet been transcribed. If you wish to help transcribe
 them, please submit a
 [pull request](https://github.com/DOS-History/Paterson-Listings/pulls). Only
 contributions that provide direct transcriptions of the listings or correct
 typos in existing transcriptions will be merged.
 ## Compiling/Assembling
 Most of the sources here target Seattle Computer Products' ASM assembler, so
 you will need a copy. It can be obtained from any release of 86-DOS or MS-DOS
 by Seattle Computer Products. You will also need the `HEX2BIN` utility from
 Seattle Computer Products to convert Intel HEX objects produced by the
 assembler into binaries.
 The simplest way to assemble a source file is to run
 `ASM <FILENAME-NO-EXTENSION>`, followed by `HEX2BIN <FILENAME-NO-EXTENSION>`.
 For example, to assemble `86DOS.ASM` into the binary `86DOS.COM`, run:
 ```
 A:ASM 86DOS
 Seattle Computer Products 8086 Assembler Version 2.24
 Copyright 1979,80,81 by Seattle Computer Products, Inc.
 Error Count =    0
 A:HEX2BIN 86DOS
 A:
 ```
@@ -0,0 +1,94 @@
 From: Yufeng Gao
 To: Tim Paterson
 Date: Thu, 24 Apr 2025 11:17:51 +0000
 Subject: 86-DOS Printouts
 Dear Mr. Paterson,
 I hope you've had a wonderful Easter. I'm reaching out to you regarding 86-DOS
 source code printouts. I'm a huge fan of 86-DOS, and just over a year ago, I
 completed a full source code reconstruction of 86-DOS 0.11 - the earliest
 surviving version of DOS.
 Recently, Bill Gates released a scanned listing of Altair BASIC 1.3, which
 brought to mind the "6-inch stack of printouts" you mentioned in your email to
 Len Shustek. A friend of mine, Rich Cini, suggested that your printouts might
 include the original source code for 86-DOS 1.00. I wanted to ask whether you
 still have those printouts, and if so, whether you'd be open to having them
 scanned and digitised.
 As 86-DOS approaches its 45th anniversary, I believe this would be a timely
 opportunity to preserve and revive the original source code. To make this
 happen, I'm more than happy to assist in any way I can. I have the equipment
 and time to produce high-DPI scans and to transcribe the listings manually.
 Thank you for considering this request, and I hope to hear from you soon.
 Best regards,
 Yufeng Gao
 -------------------------------------------------------------------------------
 From: Tim Paterson
 To: Yufeng Gao
 Cc: Richard Cini
 Date: Thu, 24 Apr 2025 17:30:43 +0000
 Subject: RE: 86-DOS Printouts
 The listing stack is actually only 3.5" (I found a bunch of blank paper at the
 bottom).  Here is the inventory:
  - DOS 1.25
  - DOS snapshot 7/8/81
  - DOS snapshot 6/16/81
  - DOS diff: 5/5/81 vs. 6/16/81
  - EDLIN diff: 5/5/81 vs. 7/1/81
  - CHKDSK snapshot 7/28/81
  - CHKDSK snapshot 6/16/81
  - SCP Assembler 2.40
  - SCP Assembler 2.43
  - MS BASIC compiler runtime library 11/13/81
 The last item was my area of responsibility at MS at the time, and takes up
 half the stack.  Most of the listings are from an MS line printer, and print
 quality is not great.
 Getting around to packing and shipping is the hard part.
 Tim Paterson
 -------------------------------------------------------------------------------
 From: Richard Cini
 To: Tim Paterson
 Cc: Yufeng Gao
 Date: Thu, 24 Apr 2025 18:26:22 +0000
 Subject: RE: 86-DOS Printouts
 That's wonderful, Tim, thanks for taking a look at that stack. That's some
 great stuff to archive. The various DOS snapshot dates seem unfamiliar to me.
 Do you remember the significance of 5/5/81 versus the other two dates? I do
 remember reading in a book that there was some last minute bug squashing so
 maybe that's it. 
 Rich
 -------------------------------------------------------------------------------
 From: Tim Paterson
 To: Richard Cini
 Cc: Yufeng Gao
 Date: Thu, 24 Apr 2025 18:32:58 +0000
 Subject: RE: 86-DOS Printouts
 There was ongoing work on DOS so the date is the OS file time stamp of the last
 change. It does not correspond to any release or version.
 The 5/5/81 date should be very close if not identical to the v1.00 release
 dated 4/28/81. The difference could be the date it was uploaded to the MS
 server.
 Tim Paterson