li $v0,4 # code 4 == print string
la $a0,message # $a0 == address of the string
syscall # Ask the operating system to
# perform the service.
. . . .
.data
message: .asciiz "Intruder Alert!\n"
You are now ready to see the program you probably expected to see in Chapter One. The following program prints the string, then calls the exit service.
# hello.asm
#
.text
.globl main
main:
li $v0,4 # code 4 == print string
la $a0,string # $a0 == address of the string
syscall # Invoke the exception handler.
li $v0,10 # code 10 == exit
syscall # Halt the program.
.data
string: .asciiz "Hello SPIM!\n"
The string is printed to the monitor window of the simulator. The program is complete, and can be copied into a source file and run as is. But see the next page first.
On a real (hardware) computer, what is the exception handler?