Как перевести древний код на asm86, в fasm

;This is a disk boot routine for the 1771/1791 type disk
;controllers.  It would normally reside on track 0,
;sector 1, to be loaded by the "B" command of the
;monitor at address 200H.  By changing the equates
;below, it may be configured to load any size of
;program at any address.  The program is assumed to
;occupy consecutive sectors starting at track 0, sector
;2, and will begin exection at its load address (which
;must be a 16-byte boundary) with the Instruction
;Pointer set to zero.
 
; Variations are available for the Cromemco 4FDC with
; large disks, the 4FDC with small disks, the Tarbell
; single-density controller, and the Tarbell double-
; density controller. Select one.
 
CROMEMCOSMALL:  EQU 0
CROMEMCOLARGE:  EQU 0
TARBELLSINGLE:  EQU 0
TARBELLDOUBLE:  EQU 1
 
LOAD:   EQU 400H    ;Address to load program
SEG:    EQU 40H ;LOAD/10H
SECTOR: EQU 8   ;No. of 128-byte sectors to load
BOOTER: EQU 200H    ;"B" command puts booter here
 
;**************************************************************
 
CROMEMCO:   EQU CROMEMCOLARGE+CROMEMCOSMALL
TARBELL:    EQU TARBELLSINGLE+TARBELLDOUBLE
 
WD1771: EQU CROMEMCO+TARBELLSINGLE
WD1791: EQU TARBELLDOUBLE
 
SMALL:  EQU CROMEMCOSMALL
LARGE:  EQU CROMEMCOLARGE+TARBELL
 
    IF  SMALL
MAXSECT:EQU 18
    ENDIF
 
    IF  LARGE
MAXSECT:EQU 26
    ENDIF
 
    IF  TARBELL
DONEBIT:EQU 80H
DISK:   EQU 78H
    ENDIF
 
    IF  CROMEMCO
DONEBIT:EQU 1
DISK:   EQU 30H
    ENDIF
 
    IF  WD1771
READCOM:EQU 88H
    ENDIF
 
    IF  WD1791
READCOM:EQU 80H
    ENDIF
 
    IF  CROMEMCOLARGE
WAITBYTE:EQU    0B1H
    ENDIF
 
    IF  CROMEMCOSMALL
WAITBYTE:EQU    0A1H
    ENDIF
 
    ORG BOOTER
    PUT 100H
 
    XOR AX,AX
    MOV DS,AX
    MOV ES,AX
    MOV SS,AX
    MOV SP,BOOTER   ;For debugging purposes
    UP
    MOV DI,LOAD
    MOV DX,SECTOR
    MOV BL,2
SECT:
    MOV AL,0D0H     ;Force Interrupt command
    OUT DISK        ;To force Type I status
    AAM
    CMP BL,MAXSECT+1
    JNZ NOSTEP
    MOV AL,58H      ;Step in with update
    CALL    DCOM
    MOV BL,1
NOSTEP:
    MOV AL,BL
    OUTB    DISK+2
 
    IF  CROMEMCO
    MOV AL,WAITBYTE
    OUT DISK+4      ;Turn on hardware wait
    ENDIF
 
    INB DISK        ;Get head load status
    NOT AL
    AND AL,20H
    JZ  OUTCOM
    MOV AL,4
OUTCOM:
    OR  AL,READCOM
    OUTB    DISK
    MOV CX,128
    PUSH    DI
READ:
    INB DISK+4
    TEST    AL,DONEBIT
 
    IF  TARBELL
    JZ  DONE
    ENDIF
 
    IF  CROMEMCO
    JNZ DONE
    ENDIF
 
    INB DISK+3
    STOB
    LOOP    READ
DONE:
    POP DI
    CALL    GETSTAT
    AND AL,9CH
    JNZ SECT
    ADD DI,128
    INC BL
    DEC DX
    JNZ SECT
    JMP 0,SEG
 
DCOM:
    OUT DISK
    AAM
GETSTAT:
    INB DISK+4
    TEST    AL,DONEBIT
 
    IF  TARBELL
    JNZ GETSTAT
    ENDIF
 
    IF  CROMEMCO
    JZ  GETSTAT
    ENDIF
 
    IN  DISK
    RET


; Load 86-DOS
 
    PUSH    DS
    MOV AX,DOSSEG   ; Set segment register for loading DOS.
    MOV DS,AX
    XOR BX,BX       ; Offset in DOSSEG is zero.
    MOV AL,BL       ; Drive 0.
    MOV CX,DOSLEN
    MOV DX,DOSSECT
    CALL    READ,40H
    POP DS
 
    MOV SI,INITTAB
    CALL    0,DOSSEG

    MOV DX,100H
    MOV AH,26       ;Set DMA address
    INT 21H
    MOV CX,[6]      ;Get size of segment
    MOV BX,DS       ;Save segment for later
;DS must be set to CS so we can point to the FCB
    MOV AX,CS
    MOV DS,AX
    MOV DX,FCB      ;File Control Block for COMMAND.COM
    MOV AH,15
    INT 21H     ;Open COMMAND.COM
    OR  AL,AL
    JNZ COMERR      ;Error if file not found
    XOR AX,AX
    MOV [FCB+33],AX ;Set 4-byte Random Record field to
    MOV [FCB+35],AX ;   beginning of file
    INC AX
    MOV [FCB+14],AX ;Set record length field
    MOV AH,39       ;Block read (CX already set)
    INT 21H
    JCXZ    COMERR      ;Error if no records read
    TEST    AL,1
    JZ  COMERR      ;Error if not end-of-file

;Make all segment registers the same
    MOV DS,BX
    MOV ES,BX
    MOV SS,BX
    MOV SP,5CH      ;Set stack to standard value
    XOR AX,AX
    PUSH    AX      ;Put zero on top of stack for return
    MOV DX,80H
    MOV AH,26
    INT 21H     ;Set default transfer address (DS:0080)
    PUSH    BX      ;Put segment on stack
    MOV AX,100H
    PUSH    AX      ;Put address to execute within segment on stack
    RET L       ;Jump to COMMAND

; Select disk configuration:
LARGE:  EQU 0       ; Four large drives.
COMBIN: EQU 0       ; Two 8-inch and one 5.25-inch.
SMALL:  EQU 0       ; Three 5.25-inch drives.
CUSTOM: EQU 1       ; User defined.

SSDRIVE:
    DW  128     ; Sector size in bytes.
    DB  2       ; Sector per allocation unit.
    DW  54      ; Reserved sectors.
    DB  2       ; Number of allocation tables.
    DW  64      ; Number of directory entrys.
    DW  720     ; Number of sectors on the disk.
 
    IF  SMALLDS-1
SDDRIVE:            ; This is the IBM Personal Computer
    DW  512     ; disk format.
    DB  1
    DW  1
    DB  2
    DW  64
    DW  320

    CALL    READ,60H

DOSSEG: EQU ($+15)/16+60H   ; Compute segment to use for 86-DOS.