Reg		Name		Notes
$0		zero		the value 0, not changeable
$1		$at		assembler temporary; reserved for assembler use
$2		$v0		value from expression evaluation or function return
$3		$v1		value from expression evaluation or function return
$4		$a0		first argument to a function/subroutine, if needed
$5		$a1		second argument to a function/subroutine, if needed
$6		$a2		third argument to a function/subroutine, if needed
$7		$a3		fourth argument to a function/subroutine, if needed
$8..$15		$t0..$t7		temporary; must be saved by caller to subroutine; subroutine can overwrite