.model tiny
.386c
.code
org 0100h
             
                
start:
     mov ax,0305h
     mov bx,0008h
     int 16h
     mov ax,0002
     int 47H   
     mov ah,26
     int 47H
     mov ah,2
     int 47h
     xor bp,bp 
Adres:
     mov di,offset infos
     mov ah,34
     int 47h
     dec infos
     push cs
     pop es
     mov cx,sect
     mov bx,offset buffer
     call readsector
     jnc noerror
     errtr:
     mov ah,25
     mov bl,infos
     xor bh,bh
     int 47h
     mov ah,21
     mov cl,116
     int 47h
     mov ah,13
     mov si,offset errordisk
     int 47h
     mov ax,0
     int 16h
     noerror:
 adres2:
     mov di,offset infos
     mov ah,34
     int 47h
     dec infos
     mov bx,0
     mov ah,25
     int 47h
     mov bh,infos
     mov di,bp
     mov ah,21
     mov cl,7
     int 47h
lines:
     mov dx,sect
     mov cx,16
     mov ah,10
     int 47h
     mov si,offset dep
     mov ah,13
     int 47h
     mov dx,di
     mov ah,10
     int 47h
     mov ah,13
     mov si,offset spaces
     int 47h
     mov al,16
     mov cl,7
     mov ah,21
     int 47h
     mov si,di
doaline:
     mov dl,[di+offset buffer]
     mov ah,10
     mov cl,8
     int 47h
     mov ah,5
     int 47h
     inc di
     dec al
     jnz doaline
     mov di,si
     mov si,offset spaces
     mov ah,13
     int 47h
     mov al,16
     mov ah,21
     mov cl,7
     int 47h
doaline2:
     mov dl,[di+offset buffer]
     mov ah,7
     int 47h
     inc di
     dec al
     jnz doaline2
     mov ah,6
     int 47h
     dec bh
     jnz lines
     mov ah,21
     mov cl,112
     int 47h
     mov si,offset menu
     mov ah,13
     int 47h
     waitkey:
     mov ax,0
     int 16h
     cmp ax,3B00h
     jne suit
     cmp bp,8*16
     jae waitkey
     add bp,16  
     jmp adres2
     suit:
     cmp ax,3C00h
     jne suit2
     cmp bp,0
     je waitkey
     sub bp,16
     jmp adres2
     suit2:
     cmp ax,3D00h
     jne suit3
     cmp sect,2880
     ja waitkey
     inc sect
     jmp adres
     suit3:
     cmp ax,3E00h
     jne suit4
     cmp sect,0
     je waitkey
     dec sect
     jmp adres   
     suit4:
     cmp ax,3F00h
     jne suit5
     jmp adres2
     suit5:
     cmp ax,4000h
     jne suit6
     mov cx,sect
     mov bx,offset buffer
     call writesector
     jnc waitkey
     jmp errtr
     suit6:
     cmp ax,4100h
     jne suit7
     mov dword ptr [pope],'TIDE'
     mov bl,infos
     xor bh,bh
     mov ah,25
     int 47h
     mov ah,21
     mov cl,116
     int 47h
     mov si,offset menu
     mov ah,13
     int 47h
     mov ah,21
     mov cl,7
     int 47h
     mov ax,0B800h
     mov es,ax   
     mov xxyy2,3
     mov xxyy,3
     call calc1
     call calc2  
waitst:
     mov ax,0
     int 16h  
     cmp ah,41h
     jne tre
     mov dword ptr [pope],'WEIV'
     push cs
     pop es
     mov cx,sect
     mov bx,offset buffer
     call writesector
     jnc adres
     jmp errtr
tre:
     cmp al,0
     jne write      
     cmp ah,48h
     jne tre1
     cmp yy,0
     je waitst
     dec yy
     jmp cursor
tre1:
     cmp ah,50h
     jne tre2
     mov al,infos
     dec al
     xor ah,ah
     cmp yy,ax
     je waitst
     inc yy
     jmp cursor
tre2:
     cmp ah,4Dh
     jne tre4
     cmp xx,15
     je waitst
     inc xx
     jmp cursor
tre4:       
     cmp ah,4Bh
     jne waitst
     cmp xx,0
     je waitst
     dec xx
     jmp cursor
write:
     call AsciiHex2dec
     cmp cl,15
     ja waitst
     call calc1
     call calc2      
     mov byte ptr es:[bx],0112
     mov es:[bx-1],al
writs:
     mov ax,0
     int 16H
     mov ch,cl
     call AsciiHex2dec
     cmp cl,15
     ja writs
     shl ch,4
     add ch,cl
     mov es:[bx+1],al
     mov es:[si-1],ch
     mov ax,bx
     call calc3
     mov [bx],ch
     inc xx 
     cmp xx,16
     jne pasde
     inc yy
     mov xx,0h
     pasde:
     call calc1
     call calc2
     jmp waitst

cursor:
     call calc1
     call calc2
     jmp waitst
     suit7:
     cmp ax,4200h
     jne waitkey
     mov ah,27
     int 47h
     db 0CBH
     ret

calc1:
     push ax dx si
     mov ax,xx
     mov dx,xx
     shl ax,2
     shl dx,1
     add ax,dx
     add ax,25
     mov bx,YY
     mov dx,yy
     shl bx,5
     shl dx,7
     add bx,dx
     add bx,ax
     mov byte ptr es:[bx],112
     mov byte ptr es:[bx+2],112
     mov si,xxyy
     mov byte ptr es:[si],07
     mov byte ptr es:[si+2],07
     mov xxyy,bx 
     pop si dx ax
     ret

calc2:
     push ax bx dx 
     mov si,YY
     mov dx,yy
     shl si,5
     shl dx,7
     add si,dx
     mov dx,xx
     shl dx,1
     add si,dx
     add si,127
     mov byte ptr es:[si],112
     mov bx,xxyy2
     mov byte ptr es:[bx],07
     mov xxyy2,si 
     pop dx bx ax
     ret

calc3:
     push dx
     xor bx,bx
     mov bx,xx
     mov dx,yy
     shl dx,4
     add bx,dx
     add bx,bp
     add bx,offset buffer
     pop dx 
     ret

     asciihex2dec:
     cmp al,'a'
     jb nomin
     cmp al,'f'
     ja nomin
     sub al,'a'-'A'
     jmp ismaj
     nomin:
     cmp al,'A'
     jb nomaj
     cmp al,'F'
     ja nomaj
     ismaj:
     mov cl,al
     sub cl,'A'-10
     jmp endt
     nomaj:
     mov cl,al
     sub cl,'0'
     endt:
     ret   

dep db ':',0
sect dw 0
xx dw 0
yy dw 0
xxyy dw 3
xxyy2 dw 3
errordisk db 'An error has occured on drive A:, press a key to continu                   ',0
menu db 'Bottom F1, Top F2, Sectors F3&F4, Load/Save F5&F6, Mode F7, Quit F8  MODE '
pope  db 'VIEW     ',0         
spaces db  ' ³ ',0

showbuffer db 35 dup (0FFh)
Lastread dw 0FFFFh

ReadSector:
push ax cx dx si
  cmp cx,cs:lastread
  je done
  mov cs:LastRead,cx
  mov AX, CX     
  xor DX, DX
  div cs:DiskSectorsPerTrack
  mov CL, DL                    ;{ Set the sector                            }
  and CL, 63                    ;{ Top two bits are bits 8&9 of the cylinder }
  xor DX, DX
  div cs:DiskTracksPerHead
  mov CH, DL                    ;{ Set the track bits 0-7                    }
  mov AL, DH
  ror AL, 1
  ror AL, 1
  and AL, 11000000b
  or CL, AL                     ;{ Set bits 8&9 of track                     }
  xor dX, DX
  div cs:DiskHeads
  mov DH, DL                    ;{ Set the head                              }
  inc CL
  mov SI, 4
TryAgain:
  mov AL, 1
  mov DL, 0
  mov AH, 2
  int 13h
  jnc Done
  dec SI
  jnz TryAgain
mov word ptr cs:lastread,0ffffh
Done:
  pop si dx cx ax
ret  

WriteSector:
push ax cx dx si
  cmp cs:Lastread,cx
  jne nodestruct
  mov cs:Lastread,0ffffh
  nodestruct:
  mov AX, CX
  xor DX, DX
  div cs:DiskSectorsPerTrack
  mov CL, DL                    ;{ Set the sector                            }
  and CL, 63                    ;{ Top two bits are bits 8&9 of the cylinder }
  xor DX, DX
  div cs:DiskTracksPerHead
  mov CH, DL                    ;{ Set the track bits 0-7                    }
  mov AL, DH
  ror AL, 1
  ror AL, 1
  and AL, 11000000b
  or CL, AL                     ;{ Set bits 8&9 of track                     }
  xor DX, DX
  div cs:DiskHeads
  mov DH, DL                    ;{ Set the head                              }
  inc CL
  mov SI, 4
TryAgain2:
  mov AL, 1
  mov DL, 0
  mov AH, 3
  int 13h
  jnc Done2
  dec SI
  jnz TryAgain2
Done2:
  pop si dx cx ax
ret

DiskSectorsPerTrack dw 18   
DiskTracksPerHead dw 80
DiskHeads dw 2

infos db 10 dup (0)
                 
buffer equ $+4000


end start