asm x86 programs

# empty program

section .text ;the actual code
    global _start ; make label visible for linker

_start: ;label, as main() function in C
    mov	eax,1       ;system call number (sys_exit)
    int	0x80        ;call kernel ( like syscall )



# Hello world
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                   ;system call number (sys_write)
    int 0x80                    ;call kernel

    mov eax,1                   ;system call number (sys_exit)
    int 0x80                    ;call kernel

section .data
    msg db 'Hello, world!',0xa ;our dear string
    len equ $ - msg             ;length of our string