Programmer 7500

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Assembly Source File | 1987-11-02 | 8.6 KB | 624 lines

CODE SEGMENT ASSUME CS:CODE,DS:CODE ORG 100H START: JMP GO ;------------------------------------------- EVEN DW 128 DUP (0) STKTOP DW 0 CYLPERDSK EQU 80 BYTESPERSEC EQU 512 SECPERCLUS EQU 2 RESERVEDSEC EQU 1 NMBROFFATS EQU 2 ROOTENTRIES EQU 112 SECPERDISK EQU 1600 DESCRIPTOR EQU 0F0H SECPERFAT EQU 3 SECPERTRK EQU 10 NMBROFHEADS EQU 2 HIDDENSEC EQU 0 DSM EQU 57H OLD_DISKBASE DD 0 OLD23 DD 0 CYL DB 0 HEAD DB 0 SECT DB 0 RETRY_COUNT DW 0 DRIVE DB 0 BREAK DB 0 DISKBASE DB 0DFH DB 02H DB 25H DB 02H DB SECPERTRK DB 1BH DB 0FFH DB 28H ;format gap DB 00H ;fill byte DB 0FH DB 08H ; C H R N SA DB 0,0,1,2 DB 0,0,2,2 DB 0,0,3,2 DB 0,0,4,2 DB 0,0,5,2 DB 0,0,6,2 DB 0,0,7,2 DB 0,0,8,2 DB 0,0,9,2 DB 0,0,10,2 MSG1 DB 0DH,0AH,'Format successful.',0DH,0AH,24H MSG2 DB 0DH,0AH,'Format failed - track 0 unusable.',0DH,0AH,24H MSG3 DB 0DH,'Cylinder ' MSG3A DB ' ',' ' DB 'Head ' MSG3B DB ' ',24H MSG4 DB ' - error on this track.',0Dh,0Ah,24h MSG5 DB 0DH,0AH,'Format failed - error reading boot sector' DB ' from default drive.',0Dh,0Ah,24h MSG6 DB 'Drive letter (A: or B:) must be specified.',0Dh,0Ah,24h MSG7 DB 'Insert diskette and press a key when ready ' DB '(or <ESC> to abort).',0Dh,0Ah,24h MSG8 DB 0DH,0AH,'Terminated by control-break.',0DH,0AH,24H LOGO DB '800 k byte formatter for low-density diskettes' DB ' in PC/AT high-density drive',0Dh,0Ah DB 'Version 1.0 - Copyright (C) 1987, Alan D. Jones',0Dh,0Ah,0Ah DB 'Use memory-resident program "800K" to write & read ' DB 'these diskettes.',0Dh,0Ah,0Ah,24h CRLF DB 0DH,0AH,24H EVEN BOOTIMG DB 512 DUP (0) FAT DB DESCRIPTOR,0FFH,0FFH DB 509 DUP (0) DB 512 DUP (0) DB 512 DUP (0) ;------------------------------------------- ;ctrl-break routine INT23 PROC FAR MOV CS:BREAK,1 IRET INT23 ENDP ;------------------------------------------- ;routine to assure proper setting of ; "diskette state machine" byte DSMS PROC PUSH ES PUSH BX PUSH AX MOV AX,40H MOV ES,AX MOV BX,90H ADD BL,DRIVE MOV AL,ES:[BX] AND AL,0DFH OR AL,07H MOV ES:[BX],AL POP AX POP BX POP ES RET DSMS ENDP ;------------------------------------------- ;convert byte in AL to ASCII at DS:[DI] BTA PROC PUSH AX SUB AH,AH AAM ADD AX,3030H MOV [DI],AH MOV [DI+1],AL POP AX RET BTA ENDP ;------------------------------------------- ;write and verify a sector with retries WRITSEC PROC PUSH BX MOV RETRY_COUNT,5 WRSEC1: MOV DL,DRIVE MOV DH,HEAD MOV CL,SECT MOV CH,CYL POP BX PUSH BX MOV AL,1 MOV AH,3 CLD CALL DSMS INT 13H JNC WRSEC3 WRSEC2: DEC RETRY_COUNT CMP RETRY_COUNT,0 JNE WRSEC1 POP BX STC RET ;verify sector WRSEC3: MOV DL,DRIVE MOV DH,HEAD MOV CL,SECT MOV CH,CYL POP BX PUSH BX MOV AL,1 MOV AH,4 CLD CALL DSMS INT 13H JC WRSEC2 POP BX CLC RET WRITSEC ENDP ;------------------------------------------- GO: PUSH DS CLI POP SS MOV SP,OFFSET STKTOP STI ;display logo MOV DX,OFFSET LOGO MOV AH,9 INT 21H ;scan command line for drive letter MOV SI,80H SUB CH,CH MOV CL,[SI] INC SI INC SI CMP CX,3 JB CLERR SUB CX,2 CLSCL: CMP WORD PTR [SI],3A41H JE DRV0 CMP WORD PTR [SI],3A61H JE DRV0 CMP WORD PTR [SI],3A42H JE DRV1 CMP WORD PTR [SI],3A62H JE DRV1 LOOP CLSCL ;command line error CLERR: MOV DX,OFFSET MSG6 MOV AH,9 INT 21H MOV AX,4C00H INT 21H ;drive 0 (A:) DRV0: MOV DRIVE,0 JMP RDBOOTIMG ;drive 1 (B:) DRV1: MOV DRIVE,1 ;read boot sector from current drive RDBOOTIMG: MOV AH,19H INT 21H MOV BX,OFFSET BOOTIMG MOV CX,1 MOV DX,0 INT 25H ADD SP,2 JNC DRIVINIT MOV DX,OFFSET MSG5 MOV AH,9 INT 21H MOV AX,4C01H INT 21H ;initialize the floppy drive (clear change line) DRIVINIT: MOV DX,OFFSET MSG7 MOV AH,9 INT 21H MOV AH,0 INT 16H CMP AL,1BH JNE DRVINIT1 MOV AX,4C00H INT 21H DRVINIT1: MOV AH,0 MOV DL,DRIVE INT 13H MOV DL,DRIVE MOV DH,0 MOV CH,1 MOV CL,1 MOV BX,OFFSET THEEND CLD MOV AX,0201H INT 13H MOV DL,DRIVE MOV DH,0 MOV CH,0 MOV CL,1 MOV BX,OFFSET THEEND CLD MOV AX,0201H INT 13H ;grab ctrl-break interrupt MOV AX,3523H INT 21H MOV WORD PTR OLD23,BX MOV WORD PTR OLD23+2,ES MOV DX,OFFSET INT23 MOV AX,2523H INT 21H ;set up new disk_base SUB AX,AX MOV ES,AX MOV BX,78H LES BX,ES:[BX] MOV WORD PTR OLD_DISKBASE,BX MOV WORD PTR OLD_DISKBASE+2,ES SUB AX,AX MOV ES,AX MOV BX,78H MOV ES:[BX+2],DS MOV ES:[BX],OFFSET DISKBASE MOV AX,40H MOV ES,AX MOV BX,90H MOV BYTE PTR ES:[BX],DSM MOV BX,8BH MOV BYTE PTR ES:[BX],DSM MOV BX,41H MOV BYTE PTR ES:[BX],00H MOV DX,03F7H MOV AL,DSM ROL AL,1 ROL AL,1 AND AL,03H OUT DX,AL MOV CYL,0 MOV HEAD,0 ;set up sector addresses FMLOOP: MOV SI,OFFSET SA MOV CX,SECPERTRK SASET: MOV AL,CYL MOV BYTE PTR [SI],AL MOV AL,HEAD MOV BYTE PTR [SI+1],AL ADD SI,4 LOOP SASET ;display status message MOV AL,CYL MOV DI,OFFSET MSG3A CALL BTA MOV AL,HEAD MOV DI,OFFSET MSG3B CALL BTA MOV DX,OFFSET MSG3 MOV AH,9 INT 21H ;format a track MOV RETRY_COUNT,5 BIOSCL1: MOV DL,DRIVE MOV DH,HEAD MOV CL,1 MOV CH,CYL MOV BX,OFFSET SA PUSH DS POP ES MOV AL,SECPERTRK MOV AH,5 CLD CALL DSMS INT 13H JNC VFYTRK DEC_RETRY: MOV DL,DRIVE MOV AH,0 CALL DSMS INT 13H DEC RETRY_COUNT CMP RETRY_COUNT,0 JNE BIOSCL1 JMP FMTERR ;verify the track VFYTRK: MOV DL,DRIVE MOV DH,HEAD MOV CL,1 MOV CH,CYL MOV BX,OFFSET THEEND MOV AL,SECPERTRK MOV AH,2 CLD CALL DSMS INT 13H JC DEC_RETRY JMP INCTRK ;bad track - flag clusters in FAT image FMTERR: ;display message MOV DX,OFFSET MSG4 MOV AH,9 INT 21H ;read sectors one at a time to find bad ones MOV SECT,1 READSINGLE: MOV DL,DRIVE MOV DH,HEAD MOV CL,SECT MOV CH,CYL MOV BX,OFFSET THEEND MOV AL,1 MOV AH,2 CLD CALL DSMS INT 13H JNC NSSECT ;compute sector number MOV AL,CYL MOV CL,SECPERTRK*2 MUL CL MOV CL,SECT DEC CL SUB CH,CH ADD AX,CX CMP HEAD,0 JE CCN ADD AX,SECPERTRK ;compute cluster number CCN: SUB AX,RESERVEDSEC SUB AX,NMBROFFATS*SECPERFAT SUB AX,(ROOTENTRIES*32)/BYTESPERSEC SUB DX,DX MOV CX,SECPERCLUS DIV CX ADD AX,2 ;compute offset into table MOV CL,1 AND CL,AL SHL CL,1 SHL CL,1 MOV DX,AX SHR AX,1 ADD AX,DX ;write FF7's MOV BX,OFFSET FAT ADD BX,AX MOV AX,0FF7H SHL AX,CL OR [BX],AX ;next sector on track NSSECT: INC SECT CMP SECT,SECPERTRK JBE READSINGLE ;increment to next track INCTRK: CMP BREAK,1 JNE INCHEAD JMP BREAKEXIT INCHEAD: INC HEAD CMP HEAD,1 JA INCTRK2 JMP FMLOOP INCTRK2: MOV HEAD,0 INC CYL CMP CYL,CYLPERDSK JNB SENDLF JMP FMLOOP ;display CRLF SENDLF: MOV DX,OFFSET CRLF MOV AH,9 INT 21H ;plug in correct media parameters MOV BX,OFFSET BOOTIMG MOV WORD PTR [BX+11],BYTESPERSEC MOV BYTE PTR [BX+13],SECPERCLUS MOV WORD PTR [BX+14],RESERVEDSEC MOV BYTE PTR [BX+16],NMBROFFATS MOV WORD PTR [BX+17],ROOTENTRIES MOV WORD PTR [BX+19],SECPERDISK MOV BYTE PTR [BX+21],DESCRIPTOR MOV WORD PTR [BX+22],SECPERFAT MOV WORD PTR [BX+24],SECPERTRK MOV WORD PTR [BX+26],NMBROFHEADS MOV WORD PTR [BX+28],HIDDENSEC ;write diskette boot sector PUSH DS POP ES MOV CYL,0 MOV HEAD,0 MOV SECT,1 MOV BX,OFFSET BOOTIMG CALL WRITSEC JC FATALERR CMP BREAK,1 JE BREAKEXIT ;write first copy of FAT MOV SECT,2 MOV BX,OFFSET FAT CALL WRITSEC JC FATALERR ADD BX,512 MOV SECT,3 CALL WRITSEC JC FATALERR ADD BX,512 MOV SECT,4 CALL WRITSEC JC FATALERR CMP BREAK,1 JE BREAKEXIT ;write second copy of FAT MOV SECT,5 MOV BX,OFFSET FAT CALL WRITSEC JC FATALERR ADD BX,512 MOV SECT,6 CALL WRITSEC JC FATALERR ADD BX,512 MOV SECT,7 CALL WRITSEC JC FATALERR CMP BREAK,1 JE BREAKEXIT ;display "ok" msg MOV DX,OFFSET MSG1 MOV AH,9 INT 21H JMP RESTORE ;error FATALERR: MOV DX,OFFSET MSG2 MOV AH,9 INT 21H JMP RESTORE ;control-break exit BREAKEXIT: MOV DX,OFFSET MSG8 MOV AH,9 INT 21H ;restore BIOS parameters + INT 23H ; and exit RESTORE: SUB AX,AX MOV ES,AX MOV BX,78H MOV AX,WORD PTR OLD_DISKBASE MOV ES:[BX],AX MOV AX,WORD PTR OLD_DISKBASE+2 MOV ES:[BX+2],AX LDS DX,OLD23 MOV AX,2523H INT 21H MOV AX,4C00H INT 21H THEEND LABEL BYTE CODE ENDS END START