;        Disassembly of file :FPHD.COM
;
;        Define common ASCII control codes.
;
HT       EQU   9
LF       EQU   10
FF       EQU   12
CR       EQU   13
EOF      EQU   26
;
;        Define MSDOS/PCDOS functions.
;
_OUTSTR  EQU   9
_TSR     EQU   49
;
;      Macro to generate MSDOS/PCDOS calls.
;
MSDOS    MACRO  name
         IFDEF  &name
         MOV    AH,&name
         ENDIF
         INT    21H
         ENDM
;
Code_Seg SEGMENT PUBLIC
L0005H   EQU   00005H
L0008H   EQU   00008H
L0300H   EQU   00300H
L0A0DH   EQU   00A0DH
L2513H   EQU   02513H
L3513H   EQU   03513H
L4C00H   EQU   04C00H
Code_Seg ENDS
;
;
Code_Seg SEGMENT PUBLIC
;
         ASSUME CS:Code_Seg,DS:Code_Seg
         ORG   00100H
L0100H:  JMP   SHORT L013AH  
L0102H:  DB    0,0               ; put address of real int 13h here
L0104H:  DB    0,0
L0106H:  CMP   DL,3              ;INT 13H comes here first now   
         JBE   L0135H            ;0-3 means floppy               
         CMP   AH,4              ;function 4 is verify           
         JNZ   L011AH  
         CMP   CX,1              ;cylinder 0, sector 1           
         JNZ   L011AH  
         CMP   DH,0              ;head 0                         
         JZ    L012EH            ;don't let it mess with part. tb
L011AH:  CMP   AH,0BH            ;is it write ECC?               
         JZ    L012EH		; yes, then error
         CMP   AH,5              ;is it format cylinder?         
         JZ    L012EH  
L0124H:  CMP   AH,6              ;is it format bad cylinder?     
         JZ    L012EH  
         CMP   AH,7              ;is it format starting at CL    
         JNZ   L0135H            ;not one of these bad ones      
L012EH:  MOV   AX,OFFSET L0300H  ;set write-protect error return code
         STC                     ;Show error on return           
         DB    0CAH              ;*** FAR RETURN ***
L0133H:  DB    0,0               ; ADD   AL,BYTE PTR [BX+SI]
L0135H:  JMP   DWORD PTR CS:[L0102H]
L013AH:  MOV   AX,OFFSET L3513H  ;Get interupt vector.
         MSDOS
         MOV   DI,BX
         MOV   DX,BX
         MOV   SI,OFFSET L0106H  ;Set far jump to real int 13    
         MOV   CX,OFFSET L0008H
         REPZ CMPSB              ;Compare strings.
         JZ    L0171H            ;see if have already installed  
         MOV   DI,BX
         MOV   SI,OFFSET L0135H
         MOV   CX,OFFSET L0005H
         REPZ CMPSB              ;Compare strings.
         JNZ   L0189H  
         SUB   DX,2FH
         PUSH  DS
         PUSH  ES
         POP   DS
         MOV   AX,OFFSET L2513H  ;Set int vector (AL) to DS:DX
         MSDOS
         POP   DS
         MOV   DX,OFFSET L01ACH
         MSDOS _OUTSTR           ;Display string at (DS:DX).
         MOV   AX,OFFSET L4C00H  ;Terminate a process.
         MSDOS
L0171H:  ADD   DX,2FH
L0174H:  PUSH  DS
         PUSH  ES
         POP   DS
         MOV   AX,OFFSET L2513H  ;Set int vector (AL) to DS:DX
         MSDOS
         POP   DS
         MOV   DX,OFFSET L01F6H
L0180H:  MSDOS _OUTSTR           ;Display string at (DS:DX).
         MOV   AX,OFFSET L4C00H  ;Terminate a process.
L0187H:  MSDOS
L0189H:  MOV   DX,OFFSET L01ACH
         MSDOS _OUTSTR           ;Display string at (DS:DX).
         MOV   WORD PTR [L0102H],BX
         MOV   WORD PTR [L0104H],ES
         MOV   DX,OFFSET L0106H
         MOV   AX,OFFSET L2513H  ;Set int vector (AL) to DS:DX
         MSDOS
         MOV   DX,OFFSET L013AH
         MOV   CL,OFFSET 4
         SHR   DX,CL
         INC   DX
         MSDOS _TSR              ;Terminate and stay resident.
L01ACH:  DB    CR,LF,'Your hard disk is now Format-protected.',CR
         DB    LF,'Run FPHD again to turn it OFF'
         DB    '.$'
L01F6H:  DB    CR,LF
L01F8H:  DB    'FPHD is now OFF (no hard disk protection).',CR,LF
L0224H:  DB    'Run it again to turn it ON.'
L023FH:  DB    '$'
L0240H:  DB    'Note: the OFF/ON func will not work if you install '
L0274H:  DB    'another prog that grabs INT 13 after you'
L029BH:  DB    ' install FPHD.$'
L02A9H:  DB    '10/28/8'
L02B0H:  DB    '5  JKW  '
         DB    0,0,0,0,0,0
         DB    0,0,0,0,0,0
         DB    0,0,0,0,0,0
         DB    0,0,0,0
L02CEH:  DB    0,0
L02D0H:  DB    0,0,0,0,0,0
         DB    0,0,0,0,0,0
         DB    0,0,0,0
L02E0H:  DB    0,0,0
L02E3H:  DB    0,0,0,0,0,0
         DB    0,0,0,0,0,0
L02EFH:  DB    0,0,0,0,0,0
         DB    0,0,0,0,0,0
         DB    0,0,0,0
         DB    0
Code_Seg ENDS
         END   L0100H