;This program shows 'Hello world!' on the screen.
section .text 
   global _start			;must be declared for linker (ld)

msg  	db	"Hello world!",0xa	;our dear string 
len     equ     $ - msg			;length of our dear string 

_syscall:                       ;system call 
       int     0x25 
       ret 

_start:                         ;tell linker entry point 

       push    dword len       ;message length 
       push    dword msg       ;message to write 
       push    dword 1         ;file descriptor (stdout) 
       mov     eax,0x3         ;system call number (sys_write) 
       call    _syscall        ;call kernel 
       add     esp,12          ;clean stack (3 * 4) 

       push    dword 0         ;exit code 
       mov     eax,0x3f        ;system call number (sys_exit) 
       call    _syscall        ;call kernel 
                               ;no need to clean stack