ORG	0000H
		LJMP	MAIN			
		ORG	0013H			
		SETB	P1.3			
		MOV	R3,#255		
BACK:		DJNZ	R3,BACK		
		CLR	P1.3			
		RETI				
		ORG	30H
MAIN:		MOV	IE,#10000100B	
HERE:		SJMP	HERE			
		END