Oduzimanje dva broja (negativan rezultat)

; multi-segment executable file template.

data segment
    a db ?
    b db ?
    zn db ?
    rez db ?
    razmak db " ", "$"
    minus db "-", "$"
    nr db 10, 13, "$"
    pkey db "press any key...$"
ends

stack segment
    dw   128  dup(0)
ends

code segment
start:
; set segment registers:
    mov ax, data
    mov ds, ax
    mov es, ax

    mov ah,1
    int 21h
    sub al, 48
    mov a, al
    mov ch, a

    int 21h
    sub al, 48
    mov b, al
    mov dh, b

    cmp ch, dh
    jge oduz1
    jmp oduz2

    oduz1:
    sub ch, dh
    mov rez, ch
    add rez, 48
    mov dl, rez
    mov ah, 2
    int 21h
    jmp kraj

    oduz2:
    sub dh, ch
    mov rez, dh
    add rez, 48
    lea dx, minus
    mov ah, 9
    int 21h
    mov dl, rez
    mov ah, 2
    int 21h

    kraj:


    lea dx, pkey
    mov ah, 9
    int 21h        ; output string at ds:dx

    ; wait for any key....
    mov ah, 1
    int 21h

    mov ax, 4c00h ; exit to operating system.
    int 21h
ends

end start ; set entry point and stop the assembler.