Collection of Tools & Utilities/Collection of Tools and Utilities.iso/dskut/800ks.zip/800KFMAT.ASM

Assembly Source File | 1987-11-02 | 9KB | 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"