; OSX, Nasm, AMD64
section .text
global start

start:
        mov rax, 2000004h ; WRITE
        mov rdi, 1
        lea rsi, [rel msg]
        mov rdx, 2
        syscall

        mov rax, 2000001h ; EXIT
        xor rdi, rdi
        syscall

section .data
msg db "Hi"
a db 80h