Microprocessors / MASM assembler and linker

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APPENDER.ASM

;Program APPENDER.ASM: Append a short message line to a text file. ; .MODEL SMALL .DATA FILENAME DB 'letter.txt',0 HANDLE DW ? FBUFF DB 0DH,0AH,'This line was not here before...',0DH,0AH STAT DB 'The file LETTER.TXT has been appended',0DH,0AH,'$' FLEN EQU STAT - FBUFF ;calculate length of FBUFF OEMSG DB 'Cannot open LETTER.TXT.$' MEMSG DB 'Cannot position file pointer.$' WFMSG DB 'Cannot write to LETTER.TXT.$' CFMSG DB 'Cannot close LETTER.TXT.$' .CODE .STARTUP CALL OPENFILE ;open LETTER.TXT JC EXIT ;jump if error CALL MOVEPTR ;move file pointer to end of file CALL WRITEFILE ;write to LETTER.TXT CALL CLOSEFILE ;close LETTER.TXT EXIT: .EXIT OPENFILE PROC NEAR MOV AH,3DH ;open file with handle function LEA DX,FILENAME ;set up pointer to ASCIIZ string MOV AL,2 ;read/write access INT 21H ;DOS call JC OPENERR ;jump if error MOV HANDLE,AX ;save file handle RET OPENERR: LEA DX,OEMSG ;set up pointer to error message MOV AH,9 ;display string function INT 21H ;DOS call STC ;set error flag RET OPENFILE ENDP MOVEPTR PROC NEAR MOV AH,42H ;position file pointer function MOV AL,2 ;offset from end method MOV BX,HANDLE ;load file handle MOV CX,0 ;offset = 0 from end MOV DX,0 INT 21H ;DOS call JC MOVERR RET MOVERR: LEA DX,MEMSG ;set up pointer to error message MOV AH,9 ;display string function INT 21H ;DOS call STC ;set error flag RET MOVEPTR ENDP WRITEFILE PROC NEAR MOV AH,40H ;write to file function MOV BX,HANDLE ;load file handle LEA DX,FBUFF ;set up pointer to data buffer MOV CL,FLEN ;load buffer length SUB CH,CH ;fix bytes-to-write value INT 21H ;DOS call JC WRITERR ;jump if error RET WRITERR: LEA DX,WFMSG ;set up pointer to error message MOV AH,9 ;display string function INT 21H ;DOS call STC ;set error flag EOFF: RET WRITEFILE ENDP CLOSEFILE PROC NEAR MOV AH,3EH ;close file with handle function MOV BX,HANDLE ;load file handle INT 21H ;DOS call JC CLOSERR ;jump if error RET CLOSERR: LEA DX,CFMSG ;set up pointer to error message MOV AH,9 ;display string function INT 21H ;DOS call STC ;set error flag RET CLOSEFILE ENDP END

APPENDER.EXE

appender.lst

Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:54:54 appender.asm Page 1 - 1 ;Program APPENDER.ASM: Append a short message line to a text file. ; .MODEL SMALL 0000 .DATA 0000 6C 65 74 74 65 72 FILENAME DB 'letter.txt',0 2E 74 78 74 00 000B 0000 HANDLE DW ? 000D 0D 0A 54 68 69 73 FBUFF DB 0DH,0AH,'This line was not here before...',0DH,0AH 20 6C 69 6E 65 20 77 61 73 20 6E 6F 74 20 68 65 72 65 20 62 65 66 6F 72 65 2E 2E 2E 0D 0A 0031 54 68 65 20 66 69 STAT DB 'The file LETTER.TXT has been appended',0DH,0AH,'$' 6C 65 20 4C 45 54 54 45 52 2E 54 58 54 20 68 61 73 20 62 65 65 6E 20 61 70 70 65 6E 64 65 64 0D 0A 24 = 0024 FLEN EQU STAT - FBUFF ;calculate length of FBUFF 0059 43 61 6E 6E 6F 74 OEMSG DB 'Cannot open LETTER.TXT.$' 20 6F 70 65 6E 20 4C 45 54 54 45 52 2E 54 58 54 2E 24 0071 43 61 6E 6E 6F 74 MEMSG DB 'Cannot position file pointer.$' 20 70 6F 73 69 74 69 6F 6E 20 66 69 6C 65 20 70 6F 69 6E 74 65 72 2E 24 008F 43 61 6E 6E 6F 74 WFMSG DB 'Cannot write to LETTER.TXT.$' 20 77 72 69 74 65 20 74 6F 20 4C 45 54 54 45 52 2E 54 58 54 2E 24 00AB 43 61 6E 6E 6F 74 CFMSG DB 'Cannot close LETTER.TXT.$' 20 63 6C 6F 73 65 20 4C 45 54 54 45 52 2E 54 58 54 2E 24 0000 .CODE .STARTUP 0017 E8 000F CALL OPENFILE ;open LETTER.TXT 001A 72 09 JC EXIT ;jump if error 001C E8 0024 CALL MOVEPTR ;move file pointer to end of file 001F E8 003E CALL WRITEFILE ;write to LETTER.TXT 0022 E8 0058 CALL CLOSEFILE ;close LETTER.TXT 0025 EXIT: .EXIT 0029 OPENFILE PROC NEAR 0029 B4 3D MOV AH,3DH ;open file with handle function 002B 8D 16 0000 R LEA DX,FILENAME ;set up pointer to ASCIIZ string 002F B0 02 MOV AL,2 ;read/write access 0031 CD 21 INT 21H ;DOS call 0033 72 04 JC OPENERR ;jump if error 0035 A3 000B R MOV HANDLE,AX ;save file handle 0038 C3 RET 0039 8D 16 0059 R OPENERR: LEA DX,OEMSG ;set up pointer to error message 003D B4 09 MOV AH,9 ;display string function 003F CD 21 INT 21H ;DOS call 0041 F9 STC ;set error flag 0042 C3 RET 0043 OPENFILE ENDP 0043 MOVEPTR PROC NEAR 0043 B4 42 MOV AH,42H ;position file pointer function 0045 B0 02 MOV AL,2 ;offset from end method 0047 8B 1E 000B R MOV BX,HANDLE ;load file handle 004B B9 0000 MOV CX,0 ;offset = 0 from end 004E BA 0000 MOV DX,0 0051 CD 21 INT 21H ;DOS call 0053 72 01 JC MOVERR 0055 C3 RET 0056 8D 16 0071 R MOVERR: LEA DX,MEMSG ;set up pointer to error message 005A B4 09 MOV AH,9 ;display string function 005C CD 21 INT 21H ;DOS call 005E F9 STC ;set error flag 005F C3 RET 0060 MOVEPTR ENDP 0060 WRITEFILE PROC NEAR 0060 B4 40 MOV AH,40H ;write to file function 0062 8B 1E 000B R MOV BX,HANDLE ;load file handle 0066 8D 16 000D R LEA DX,FBUFF ;set up pointer to data buffer 006A B1 24 MOV CL,FLEN ;load buffer length 006C 2A ED SUB CH,CH ;fix bytes-to-write value 006E CD 21 INT 21H ;DOS call 0070 72 01 JC WRITERR ;jump if error 0072 C3 RET 0073 8D 16 008F R WRITERR: LEA DX,WFMSG ;set up pointer to error message 0077 B4 09 MOV AH,9 ;display string function 0079 CD 21 INT 21H ;DOS call 007B F9 STC ;set error flag 007C C3 EOFF: RET 007D WRITEFILE ENDP 007D CLOSEFILE PROC NEAR 007D B4 3E MOV AH,3EH ;close file with handle function 007F 8B 1E 000B R MOV BX,HANDLE ;load file handle 0083 CD 21 INT 21H ;DOS call 0085 72 01 JC CLOSERR ;jump if error 0087 C3 RET 0088 8D 16 00AB R CLOSERR: LEA DX,CFMSG ;set up pointer to error message 008C B4 09 MOV AH,9 ;display string function 008E CD 21 INT 21H ;DOS call 0090 F9 STC ;set error flag 0091 C3 RET 0092 CLOSEFILE ENDP END �Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:54:54 appender.asm Symbols 2 - 1 Segments and Groups: N a m e Size Length Align Combine Class DGROUP . . . . . . . . . . . . . GROUP _DATA . . . . . . . . . . . . . 16 Bit 00C4 Word Public 'DATA' _TEXT . . . . . . . . . . . . . 16 Bit 0092 Word Public 'CODE' Procedures, parameters and locals: N a m e Type Value Attr CLOSEFILE . . . . . . . . . . . P Near 007D _TEXT Length= 0015 Public CLOSERR . . . . . . . . . . . L Near 0088 _TEXT MOVEPTR . . . . . . . . . . . . P Near 0043 _TEXT Length= 001D Public MOVERR . . . . . . . . . . . . L Near 0056 _TEXT OPENFILE . . . . . . . . . . . . P Near 0029 _TEXT Length= 001A Public OPENERR . . . . . . . . . . . L Near 0039 _TEXT WRITEFILE . . . . . . . . . . . P Near 0060 _TEXT Length= 001D Public WRITERR . . . . . . . . . . . L Near 0073 _TEXT EOFF . . . . . . . . . . . . . L Near 007C _TEXT Symbols: N a m e Type Value Attr @CodeSize . . . . . . . . . . . Number 0000h @DataSize . . . . . . . . . . . Number 0000h @Interface . . . . . . . . . . . Number 0000h @Model . . . . . . . . . . . . . Number 0002h @Startup . . . . . . . . . . . . L Near 0000 _TEXT @code . . . . . . . . . . . . . Text _TEXT @data . . . . . . . . . . . . . Text DGROUP @fardata? . . . . . . . . . . . Text FAR_BSS @fardata . . . . . . . . . . . . Text FAR_DATA @stack . . . . . . . . . . . . . Text DGROUP CFMSG . . . . . . . . . . . . . Byte 00AB _DATA EXIT . . . . . . . . . . . . . . L Near 0025 _TEXT FBUFF . . . . . . . . . . . . . Byte 000D _DATA FILENAME . . . . . . . . . . . . Byte 0000 _DATA FLEN . . . . . . . . . . . . . . Number 0024h HANDLE . . . . . . . . . . . . . Word 000B _DATA MEMSG . . . . . . . . . . . . . Byte 0071 _DATA OEMSG . . . . . . . . . . . . . Byte 0059 _DATA STAT . . . . . . . . . . . . . . Byte 0031 _DATA WFMSG . . . . . . . . . . . . . Byte 008F _DATA 0 Warnings 0 Errors

BOOTSEC.ASM

;Program BOOTSEC.ASM: Display contents of disk A's boot sector (with ASCII). ; .MODEL SMALL .DATA BMSG DB 'Boot sector for diskette in drive A:',0DH,0AH,0DH,0AH,'$' EMSG1 DB 'Error! Can not reset diskette system.',0DH,0AH,'$' EMSG2 DB 'Error! Can not read boot sector.',0DH,0AH,'$' BLANK DB ' $' PRESS DB 0DH,0AH,'Press any key for next 256 bytes...' CRLF DB 0DH,0AH,'$' DBUF DB 512 DUP(0) .CODE .STARTUP MOV AX,DS MOV ES,AX ;set up extra segment MOV AH,0 ;reset disk function MOV DL,0 ;drive A INT 13H ;BIOS call JNC OK LEA DX,EMSG1 ;set up pointer to error message PRE: MOV AH,9 ;display string function INT 21H ;DOS call JMP EXIT OK: CALL READ ;read boot sector, first try JNC OBM CALL READ ;read boot sector, second try JNC OBM CALL READ ;read boot sector, last try JNC OBM LEA DX,EMSG2 ;set up pointer to error message JMP PRE ;go process error OBM: LEA DX,BMSG ;set up pointer to boot message MOV AH,9 ;display string function INT 21H ;DOS call SUB SI,SI ;clear index pointer CALL SHOWDTA ;show first half of DTA LEA DX,PRESS ;set up pointer to press message MOV AH,9 ;display string function INT 21H ;DOS call MOV AH,1 ;read keyboard function INT 21H ;DOS call LEA DX,CRLF ;set up pointer to crlf string MOV AH,9 ;display string function INT 21H ;DOS call CALL SHOWDTA ;show second half of DTA EXIT: .EXIT READ PROC NEAR LEA BX,DBUF ;set up pointer to DTA MOV AH,2 ;read disk sectors function MOV AL,1 ;read one sector MOV DL,0 ;from drive A MOV DH,0 ;head 0 MOV CX,1 ;sector 1 INT 13H ;BIOS call RET READ ENDP SHOWDTA PROC NEAR MOV CX,16 ;load line counter NLYN: PUSH CX ;save line counter MOV AX,SI ;load pointer address CALL DISPHEX2 ;output hex address MOV DL,':' ;load colon MOV AH,2 ;display character function INT 21H ;DOS call MOV CX,16 ;load byte counter NBYT: LEA DX,BLANK ;set up pointer to blank string MOV AH,9 ;display string function INT 21H ;DOS call MOV AL,ES:DBUF[SI] ;get next byte CALL DISPHEX ;output it INC SI ;advance pointer LOOP NBYT ;repeat for next byte CALL SHOWASC ;output ASCII equivalents LEA DX,CRLF ;set up pointer to crlf string MOV AH,9 ;display string function INT 21H ;DOS call POP CX ;get line counter back LOOP NLYN ;and repeat until done RET SHOWDTA ENDP SHOWASC PROC NEAR LEA DX,BLANK ;set up pointer to blank string MOV AH,9 ;display string function INT 21H ;DOS call LEA DX,BLANK ;set up pointer to blank string MOV AH,9 ;display string function INT 21H ;DOS call SUB SI,16 ;adjust pointer PUSH CX ;save current counter MOV CX,16 ;load character counter GCHR: MOV DL,ES:DBUF[SI] ;get next byte INC SI ;advance pointer AND DL,7FH ;convert to 7-bit ASCII CMP DL,20H ;is it printable? JC BLNK ;no, go output a blank CMP AL,80H ;is it still printable? JNC BLNK AOUT: MOV AH,2 ;display character function INT 21H ;DOS call LOOP GCHR ;repeat until done POP CX ;get counter back RET BLNK: MOV DL,20H ;load blank character JMP AOUT SHOWASC ENDP DISPHEX PROC NEAR PUSH AX ;save number SHR AL,1 ;shift upper nybble down SHR AL,1 SHR AL,1 SHR AL,1 CMP AL,10 ;is nybble value less than 10? JC NHA1 ;yes, go convert and display ADD AL,7 ;add alpha bias NHA1: ADD AL,30H ;add ASCII bias MOV DL,AL ;load character MOV AH,2 ;display character function INT 21H ;DOS call POP AX ;get number back AND AL,0FH ;work with lower nybble CMP AL,10 ;is it less than 10? JC NHA2 ;yes, go convert and display ADD AL,7 ;add alpha bias NHA2: ADD AL,30H ;add ASCII bias MOV DL,AL ;load character MOV AH,2 ;display character function INT 21H ;DOS call RET DISPHEX ENDP DISPHEX2 PROC NEAR PUSH AX ;save number XCHG AH,AL ;get upper byte CALL DISPHEX ;output it POP AX ;get number back CALL DISPHEX ;output lower byte RET DISPHEX2 ENDP END

BOOTSEC.EXE

bootsec.lst

Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:56:10 bootsec.asm Page 1 - 1 ;Program BOOTSEC.ASM: Display contents of disk A's boot sector (with ASCII). ; .MODEL SMALL 0000 .DATA 0000 42 6F 6F 74 20 73 BMSG DB 'Boot sector for diskette in drive A:',0DH,0AH,0DH,0AH,'$' 65 63 74 6F 72 20 66 6F 72 20 64 69 73 6B 65 74 74 65 20 69 6E 20 64 72 69 76 65 20 41 3A 0D 0A 0D 0A 24 0029 45 72 72 6F 72 21 EMSG1 DB 'Error! Can not reset diskette system.',0DH,0AH,'$' 20 43 61 6E 20 6E 6F 74 20 72 65 73 65 74 20 64 69 73 6B 65 74 74 65 20 73 79 73 74 65 6D 2E 0D 0A 24 0051 45 72 72 6F 72 21 EMSG2 DB 'Error! Can not read boot sector.',0DH,0AH,'$' 20 43 61 6E 20 6E 6F 74 20 72 65 61 64 20 62 6F 6F 74 20 73 65 63 74 6F 72 2E 0D 0A 24 0074 20 24 BLANK DB ' $' 0076 0D 0A 50 72 65 73 PRESS DB 0DH,0AH,'Press any key for next 256 bytes...' 73 20 61 6E 79 20 6B 65 79 20 66 6F 72 20 6E 65 78 74 20 32 35 36 20 62 79 74 65 73 2E 2E 2E 009B 0D 0A 24 CRLF DB 0DH,0AH,'$' 009E 0200 [ DBUF DB 512 DUP(0) 00 ] 0000 .CODE .STARTUP 0017 8C D8 MOV AX,DS 0019 8E C0 MOV ES,AX ;set up extra segment 001B B4 00 MOV AH,0 ;reset disk function 001D B2 00 MOV DL,0 ;drive A 001F CD 13 INT 13H ;BIOS call 0021 73 0A JNC OK 0023 8D 16 0029 R LEA DX,EMSG1 ;set up pointer to error message 0027 B4 09 PRE: MOV AH,9 ;display string function 0029 CD 21 INT 21H ;DOS call 002B EB 39 JMP EXIT 002D E8 003A OK: CALL READ ;read boot sector, first try 0030 73 10 JNC OBM 0032 E8 0035 CALL READ ;read boot sector, second try 0035 73 0B JNC OBM 0037 E8 0030 CALL READ ;read boot sector, last try 003A 73 06 JNC OBM 003C 8D 16 0051 R LEA DX,EMSG2 ;set up pointer to error message 0040 EB E5 JMP PRE ;go process error 0042 8D 16 0000 R OBM: LEA DX,BMSG ;set up pointer to boot message 0046 B4 09 MOV AH,9 ;display string function 0048 CD 21 INT 21H ;DOS call 004A 2B F6 SUB SI,SI ;clear index pointer 004C E8 002D CALL SHOWDTA ;show first half of DTA 004F 8D 16 0076 R LEA DX,PRESS ;set up pointer to press message 0053 B4 09 MOV AH,9 ;display string function 0055 CD 21 INT 21H ;DOS call 0057 B4 01 MOV AH,1 ;read keyboard function 0059 CD 21 INT 21H ;DOS call 005B 8D 16 009B R LEA DX,CRLF ;set up pointer to crlf string 005F B4 09 MOV AH,9 ;display string function 0061 CD 21 INT 21H ;DOS call 0063 E8 0016 CALL SHOWDTA ;show second half of DTA 0066 EXIT: .EXIT 006A READ PROC NEAR 006A 8D 1E 009E R LEA BX,DBUF ;set up pointer to DTA 006E B4 02 MOV AH,2 ;read disk sectors function 0070 B0 01 MOV AL,1 ;read one sector 0072 B2 00 MOV DL,0 ;from drive A 0074 B6 00 MOV DH,0 ;head 0 0076 B9 0001 MOV CX,1 ;sector 1 0079 CD 13 INT 13H ;BIOS call 007B C3 RET 007C READ ENDP 007C SHOWDTA PROC NEAR 007C B9 0010 MOV CX,16 ;load line counter 007F 51 NLYN: PUSH CX ;save line counter 0080 8B C6 MOV AX,SI ;load pointer address 0082 E8 0089 CALL DISPHEX2 ;output hex address 0085 B2 3A MOV DL,':' ;load colon 0087 B4 02 MOV AH,2 ;display character function 0089 CD 21 INT 21H ;DOS call 008B B9 0010 MOV CX,16 ;load byte counter 008E 8D 16 0074 R NBYT: LEA DX,BLANK ;set up pointer to blank string 0092 B4 09 MOV AH,9 ;display string function 0094 CD 21 INT 21H ;DOS call 0096 26: 8A 84 009E R MOV AL,ES:DBUF[SI] ;get next byte 009B E8 0047 CALL DISPHEX ;output it 009E 46 INC SI ;advance pointer 009F E2 ED LOOP NBYT ;repeat for next byte 00A1 E8 000C CALL SHOWASC ;output ASCII equivalents 00A4 8D 16 009B R LEA DX,CRLF ;set up pointer to crlf string 00A8 B4 09 MOV AH,9 ;display string function 00AA CD 21 INT 21H ;DOS call 00AC 59 POP CX ;get line counter back 00AD E2 D0 LOOP NLYN ;and repeat until done 00AF C3 RET 00B0 SHOWDTA ENDP 00B0 SHOWASC PROC NEAR 00B0 8D 16 0074 R LEA DX,BLANK ;set up pointer to blank string 00B4 B4 09 MOV AH,9 ;display string function 00B6 CD 21 INT 21H ;DOS call 00B8 8D 16 0074 R LEA DX,BLANK ;set up pointer to blank string 00BC B4 09 MOV AH,9 ;display string function 00BE CD 21 INT 21H ;DOS call 00C0 83 EE 10 SUB SI,16 ;adjust pointer 00C3 51 PUSH CX ;save current counter 00C4 B9 0010 MOV CX,16 ;load character counter 00C7 26: 8A 94 009E R GCHR: MOV DL,ES:DBUF[SI] ;get next byte 00CC 46 INC SI ;advance pointer 00CD 80 E2 7F AND DL,7FH ;convert to 7-bit ASCII 00D0 80 FA 20 CMP DL,20H ;is it printable? 00D3 72 0C JC BLNK ;no, go output a blank 00D5 3C 80 CMP AL,80H ;is it still printable? 00D7 73 08 JNC BLNK 00D9 B4 02 AOUT: MOV AH,2 ;display character function 00DB CD 21 INT 21H ;DOS call 00DD E2 E8 LOOP GCHR ;repeat until done 00DF 59 POP CX ;get counter back 00E0 C3 RET 00E1 B2 20 BLNK: MOV DL,20H ;load blank character 00E3 EB F4 JMP AOUT 00E5 SHOWASC ENDP 00E5 DISPHEX PROC NEAR 00E5 50 PUSH AX ;save number 00E6 D0 E8 SHR AL,1 ;shift upper nybble down 00E8 D0 E8 SHR AL,1 00EA D0 E8 SHR AL,1 00EC D0 E8 SHR AL,1 00EE 3C 0A CMP AL,10 ;is nybble value less than 10? 00F0 72 02 JC NHA1 ;yes, go convert and display 00F2 04 07 ADD AL,7 ;add alpha bias 00F4 04 30 NHA1: ADD AL,30H ;add ASCII bias 00F6 8A D0 MOV DL,AL ;load character 00F8 B4 02 MOV AH,2 ;display character function 00FA CD 21 INT 21H ;DOS call 00FC 58 POP AX ;get number back 00FD 24 0F AND AL,0FH ;work with lower nybble 00FF 3C 0A CMP AL,10 ;is it less than 10? 0101 72 02 JC NHA2 ;yes, go convert and display 0103 04 07 ADD AL,7 ;add alpha bias 0105 04 30 NHA2: ADD AL,30H ;add ASCII bias 0107 8A D0 MOV DL,AL ;load character 0109 B4 02 MOV AH,2 ;display character function 010B CD 21 INT 21H ;DOS call 010D C3 RET 010E DISPHEX ENDP 010E DISPHEX2 PROC NEAR 010E 50 PUSH AX ;save number 010F 86 E0 XCHG AH,AL ;get upper byte 0111 E8 FFD1 CALL DISPHEX ;output it 0114 58 POP AX ;get number back 0115 E8 FFCD CALL DISPHEX ;output lower byte 0118 C3 RET 0119 DISPHEX2 ENDP END �Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:56:10 bootsec.asm Symbols 2 - 1 Segments and Groups: N a m e Size Length Align Combine Class DGROUP . . . . . . . . . . . . . GROUP _DATA . . . . . . . . . . . . . 16 Bit 029E Word Public 'DATA' _TEXT . . . . . . . . . . . . . 16 Bit 0119 Word Public 'CODE' Procedures, parameters and locals: N a m e Type Value Attr DISPHEX2 . . . . . . . . . . . . P Near 010E _TEXT Length= 000B Public DISPHEX . . . . . . . . . . . . P Near 00E5 _TEXT Length= 0029 Public NHA1 . . . . . . . . . . . . . L Near 00F4 _TEXT NHA2 . . . . . . . . . . . . . L Near 0105 _TEXT READ . . . . . . . . . . . . . . P Near 006A _TEXT Length= 0012 Public SHOWASC . . . . . . . . . . . . P Near 00B0 _TEXT Length= 0035 Public GCHR . . . . . . . . . . . . . L Near 00C7 _TEXT AOUT . . . . . . . . . . . . . L Near 00D9 _TEXT BLNK . . . . . . . . . . . . . L Near 00E1 _TEXT SHOWDTA . . . . . . . . . . . . P Near 007C _TEXT Length= 0034 Public NLYN . . . . . . . . . . . . . L Near 007F _TEXT NBYT . . . . . . . . . . . . . L Near 008E _TEXT Symbols: N a m e Type Value Attr @CodeSize . . . . . . . . . . . Number 0000h @DataSize . . . . . . . . . . . Number 0000h @Interface . . . . . . . . . . . Number 0000h @Model . . . . . . . . . . . . . Number 0002h @Startup . . . . . . . . . . . . L Near 0000 _TEXT @code . . . . . . . . . . . . . Text _TEXT @data . . . . . . . . . . . . . Text DGROUP @fardata? . . . . . . . . . . . Text FAR_BSS @fardata . . . . . . . . . . . . Text FAR_DATA @stack . . . . . . . . . . . . . Text DGROUP BLANK . . . . . . . . . . . . . Byte 0074 _DATA BMSG . . . . . . . . . . . . . . Byte 0000 _DATA CRLF . . . . . . . . . . . . . . Byte 009B _DATA DBUF . . . . . . . . . . . . . . Byte 009E _DATA EMSG1 . . . . . . . . . . . . . Byte 0029 _DATA EMSG2 . . . . . . . . . . . . . Byte 0051 _DATA EXIT . . . . . . . . . . . . . . L Near 0066 _TEXT OBM . . . . . . . . . . . . . . L Near 0042 _TEXT OK . . . . . . . . . . . . . . . L Near 002D _TEXT PRESS . . . . . . . . . . . . . Byte 0076 _DATA PRE . . . . . . . . . . . . . . L Near 0027 _TEXT 0 Warnings 0 Errors

BUFF.ASM

;Procedure KEYBUFF: Place keystrokes into buffer until CR is entered. ; .MODEL SMALL PUBLIC KEYBUFF ;for linking .CODE KEYBUFF PROC FAR MOV CL,0 ;clear character counter NEXTKEY: MOV AH,1 ;read keyboard function INT 21H ;DOS call MOV [DI],AL ;save character in buffer INC DI ;advance buffer pointer INC CL ;increment character counter CMP AL,0DH ;was last keystroke a CR? JNZ NEXTKEY ;jump if not RET KEYBUFF ENDP END

BUFF.EXE

buff.lst

Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:57:11 buff.asm Page 1 - 1 ;Procedure KEYBUFF: Place keystrokes into buffer until CR is entered. ; .MODEL SMALL PUBLIC KEYBUFF ;for linking 0000 .CODE 0000 KEYBUFF PROC FAR 0000 B1 00 MOV CL,0 ;clear character counter 0002 B4 01 NEXTKEY: MOV AH,1 ;read keyboard function 0004 CD 21 INT 21H ;DOS call 0006 88 05 MOV [DI],AL ;save character in buffer 0008 47 INC DI ;advance buffer pointer 0009 FE C1 INC CL ;increment character counter 000B 3C 0D CMP AL,0DH ;was last keystroke a CR? 000D 75 F3 JNZ NEXTKEY ;jump if not 000F CB RET 0010 KEYBUFF ENDP END �Microsoft (R) Macro Assembler Version 6.14.8444 03/25/06 09:57:11 buff.asm Symbols 2 - 1 Segments and Groups: N a m e Size Length Align Combine Class DGROUP . . . . . . . . . . . . . GROUP _DATA . . . . . . . . . . . . . 16 Bit 0000 Word Public 'DATA' _TEXT . . . . . . . . . . . . . 16 Bit 0010 Word Public 'CODE' Procedures, parameters and locals: N a m e Type Value Attr KEYBUFF . . . . . . . . . . . . P Far 0000 _TEXT Length= 0010 Public NEXTKEY . . . . . . . . . . . L Near 0002 _TEXT Symbols: N a m e Type Value Attr @CodeSize . . . . . . . . . . . Number 0000h @DataSize . . . . . . . . . . . Number 0000h @Interface . . . . . . . . . . . Number 0000h @Model . . . . . . . . . . . . . Number 0002h @code . . . . . . . . . . . . . Text _TEXT @data . . . . . . . . . . . . . Text DGROUP @fardata? . . . . . . . . . . . Text FAR_BSS @fardata . . . . . . . . . . . . Text FAR_DATA @stack . . . . . . . . . . . . . Text DGROUP 0 Warnings 0 Errors