; Function defined on pp272-273 of C64 Programmers Reference Guide
stop:
	;; Bit 7 of BUCKYSTATUS contains the state of the STOP key
	;; (Compute's Mapping the 64, p27)

	;; BASIC checks carry flag to indicate STOP or not
	lda BUCKYSTATUS
	and #$80
	beq stop_pressed

	;;  By trial and error, we know that Z + C = BREAK
	;; and that neither should be set otherwise
	lda #$ff
	clc	
	rts

stop_pressed:
	sec
	lda #$00
	rts