;
; *** Listing 9-3 ***
;
; An example of using AND reg,reg to test for the
; zero/non-zero status of a register. This is faster
; (and usually shorter) than CMP reg,0.
;
	sub	dx,dx	;set DX to 0, so we don't jump
	call	ZTimerOn
	rept	1000
	and	dx,dx	;is DX 0?
	jnz	$+2	;just jumps to the next line if
			; Z is not set (never jumps)
	endm
	call	ZTimerOff