nano hello.s
# File: hello.s -- Say Hello to MIPS Assembly Language Programmer
# Author: falcon <wuzhangjin(at)gmail.com>, 2009/01/17
# Ref:
#    [*] http://www.tldp.org/HOWTO/Assembly-HOWTO/mips.html
#    [*] MIPS Assembly Language Programmer's Guide
#    [*] See MIPS Run Linux(second version)
# Compile:
#       $ gcc -o hello hello.s
#       or
#       $ as -o hello.o hello.s
#       $ ld -e main -o hello hello.o

    .text
    .globl main
main:

    .set noreorder
    .cpload $gp       # setup the pointer to global data
    .set reorder
                      # print sth. via sys_write
    li $a0, 1         # print to standard ouput
    la $a1, stradr    # set the string address
    lw $a2, strlen    # set the string length
    li $v0, 4004      # index of sys_write:
                      # __NR_write in /usr/include/asm/unistd.h
    syscall           # causes a system call trap.

                      # exit via sys_exit
    move $a0, $0      # exit status as 0
    li $v0, 4001      # index of sys_exit
                      # __NR_exit in /usr/include/asm/unistd.h
    syscall

    .rdata
stradr: .asciiz "hello, world!\n"
strlen: .word . - stradr  # current address - the string address
# end
root@Arduino:/mnt/sda1# gcc -o hello hello.s
root@Arduino:/mnt/sda1# ./hello
hello, world!