TCOUNT	EQU		30H
FLAG	BIT		00H
		ORG		00H
		SJMP	START
		ORG		0BH
		LJMP	INT_T0
START:	CLR		FLAG		  				;標志位
		MOV		TCOUNT,#00H
		MOV		TCOUNT,#00H
		MOV		TMOD,#01H
		MOV		TH0,#(65536-1000)/256
		MOV		TL0,#(65536-1000)MOD 256
		MOV		IE,#82H						;開中斷
		SETB	TR0							;啟動定時器
		SJMP	$
INT_T0:	MOV		TH0,#(65536-1000)/256
		MOV		TL0,#(65536-1000)MOD 256
		INC		TCOUNT
		MOV		A,TCOUNT
		CJNE	A,#250,I1					;是否計滿0.25秒
		CPL		FLAG
		MOV		TCOUNT,#00H
	I1:	JB		FLAG,I2						;檢查標志位
		CPL		P1.0
		SJMP	RETUNE
	I2:	CLR		P1.0
RETUNE:	RETI
		END