MOV	A,#66H	
BACK:	MOV	P1,A		
		RR	A		
		ACALL DELAY	
		SJMP	BACK		
		...
DELAY	
		MOV	R2,#100	
H1:		MOV	R3,#255
H2:		DJNZ	R3,H2
		DJNZ	R2,H1
		RET