MIPS Mars use of syscalls for prompting & reading in integer

#MIPS assembly: Use Mars syscall to prompt user and read value typed in
.data

intPrompt:  .asciiz  "enter an integer: "

.text
    # Prompt the user ($v0=4)
    la  $a0, intPrompt
    li  $v0, 4
    syscall

    # Read in an integer ($v0=5)
    li  $v0, 5
    syscall       # value read in will be saved to $v0

    add $t1, $zero, $v0  #save integer read.