LED		BIT		P1.0
LEDBUF	EQU		30H
		ORG		00H
		LJMP	START
		ORG		03H
		LJMP	INTERRUPT
START:	CLR		LEDBUF
		CLR		LED
		MOV		TCON,#01H	;外部中斷0下降沿觸發(fā)
		MOV		IE,#81H		;打開外部中斷允許位（EX0）
							;及總中斷允許位（EA）
		LJMP	$			;等待中斷
INTERRUPT:
		PUSH	PSW			;保護(hù)現(xiàn)場(chǎng)
		CPL		LEDBUF		;取反LED
		MOV		C,LEDBUF
		MOV		LED,C
		POP		PSW			;恢復(fù)現(xiàn)場(chǎng)
		RETI
		END