nasm

section .text

    global _start

_start:

    mov edx, len ;message length

    mov ecx, msg ;message to write

    mov ebx, 1 ; file descriptor (stdout)

    mov eax, 4

    int 0x80 ; call kernel

    mov eax, 1

    int 0x80

section .data

    msg db "hello, world!", 0xa

    len equ $ - msg