4-1.asm

这是用proteus和keil两个平台一起完成的

          ORG 30H
START:    MOV A,#01H
          MOV R2,#8
LOOP:	  MOV P2,A
          CALL DELAY
		  RL  A
          DJNZ R2,LOOP
		  MOV R2,#7
LOOP1:    RR  A
          MOV P2,A
		  CALL DELAY
		  DJNZ R2,LOOP1
		  JMP  START
DELAY:    MOV R3,#100
D1:       MOV R4,#20
D2:       MOV R5,#248
          DJNZ R5,$
		  DJNZ R4,D2
		  DJNZ R3,D1
		  RET
		  END