Untitled

section .data
string1 db "Hello World!",10 ; '10' at end is line feed
section .text
global _start
_start:
 mov rdx, 0xd ; length of string is 13 bytes
 mov rsi, dword string1; set rsi to pointer to string
 mov rax, 0x1 ; syscall 1 is write
 mov rdi, 0x1 ; stdout has a file descriptor of 1
 syscall ; make the system call
 mov rax, 0x3c ; syscall 3c is exit
 syscall