### A good answer might be:

By convention, register `$a0` is used to pass the argument. But in the body of the subroutine register `$a0` is used to pass arguments to the trap handler. So a safe copy must be made in an "S" register.

# Calling the Subroutine

Here is a section of the main program. It prints out the contents of both structs:

            . . . .
            # $s1 contains the address of the first struct
            # $s2 contains the address of the second struct
            #
            # write out the first struct
            move    ____,____
            jal     PStruct

            # write out the second struct
            move    ____,____
            jal     PStruct

### QUESTION 12:

Fill in the blanks. Look back at the subroutine if needed.