sum.s

//----------------------------------------------------------------
//	sum.s: 
//
//	compile using:	$ as sum.s -o sum.o
//	link using:	$ ld sum.o -o sum
//	execute using:	$ ./sum
//
//----------------------------------------------------------------
.text                   # this section is program
    .global _start      # entry point 

_start:

  movl $1, %eax         # put 1 into eax 
  addl $8, %eax         # add 8 into eax 
  addl $48, %eax        # convert digit to ASCII 
  movl $msg, %ecx       # put address of msg into ecx 
  movb %al, (%ecx)      # store byte in al in location ecx  
                        # points to 

                        # write our string to stdout
  movl    $len,%edx     # third argument: message length
  movl    $msg,%ecx     # second: pointer to message
  movl    $1,%ebx       # sum: file handle (stdout) 
  movl    $4,%eax       # system call number (sys_write) 
  int     $0x80         # call kernel 
                        # and exit 
  movl    $0,%ebx       # sum argument: exit code 
  movl    $1,%eax       # system call number (sys_exit) 
  int     $0x80         # call kernel 

.data                   # this section is data 
msg: 
  .byte 72,10 
  len = . - msg