Write an assembly program that :

Question

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.
Do not use interrupts.

Answer 1

Assuming we are targeting an Intel x86 processor, here is a possible implementation in NASM syntax:

section .text
global _start

_start:
; Load AL by an arbitrary number
mov al, 0Bh ; example value

; Compute parity
xor ah, ah ; clear AH
mov cl, 8 ; set loop counter
.loop:
shr al, 1 ; shift right
adc ah, 0 ; add carry to AH
loop .loop ; decrement counter and loop while not zero

; Transfer result to Port 0
test ah, 1 ; check parity
jnz .odd ; jump if odd
mov al, 80h ; set even value
jmp .done ; jump to end
.odd:
mov al, 1 ; set odd value
.done:
mov dx, 0h ; Port 0 address
out dx, al ; send value to port

; Exit program
xor eax, eax
ret

Note that the solution uses a loop to calculate the parity of the input value and branches accordingly to set the output value for Port 0. The output is then written to the port using the OUT instruction, which transfers a byte from a specified register (AL in this case) to a specified I/O port (DX in this case). Finally, the program exits by returning 0 to the operating system (which indicates successful execution).