amd64 - MMX

    global _start
    section .data
        op1: db "00000000"
        op2: db 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01
    section .text

_start:

    movq xmm1, [op1]
    movq xmm2, [op2]
    paddb xmm1, xmm2
    movq [op1], xmm1

    mov ecx, op1
    mov edx, 8
    mov ebx, 1
    mov eax, 4
    int 0x80

    mov ebx, 0
    mov eax, 1
    int 80h

Ausgabe:

david@work:~$ ./nasm20241121mmx
87654321david@work:~$