Question

Write an assembly program that will:
Load AL by an arbitrary number, if there is parity even, transfer 80H to the Port 0, and if there is parity odd, transfer 01H to the Port 0.

Answer 1

Here is one possible solution in x86 assembly language:

section .text
global _start

_start:
; Load AL with an arbitrary number
mov al, 0b01101010 ; Example: load AL with 6Ch (1101100b)

; Check the parity of AL
mov ah, 0 ; Clear AH to use for parity calculation
xor edx, edx ; Clear EDX for division by 2
mov dl, al ; Copy AL to DL for division by 2
shr dl, 1 ; Divide by 2 (shift right)
jnb even ; Jump if no carry (even parity)
; Odd parity
mov al, 1 ; Set AL to 01h
jmp output ; Jump to output

even:
; Even parity
mov al, 0x80 ; Set AL to 80h

output:
; Transfer AL to Port 0 (OUT 0, AL)
mov dx, 0x0000 ; Set DX to Port 0 address
out dx, al ; Transfer AL to Port 0

; Exit program
mov eax, 1 ; Set exit code to 1
xor ebx, ebx ; Clear EBX for compatibility
int 0x80 ; Invoke system call for exit