;each bit in port 1 connect to led
;delay=0.1s

        ORG    0000H
START:  MOV     R1, #07H
        MOV     A, #11111110B
LEFT:   MOV     P1, A
        ACALL   DELAY
        RL      A
        DJNZ    R1, LEFT
        MOV     R1, #07H
        MOV     A, #01111111B
RIGHT:  MOV     P1, A
        ACALL   DELAY
        RR      A
        DJNZ    R1, RIGHT
        AJMP    START
DELAY:  MOV     R6, #250
DL1:    MOV     R7, #200
DL2:    DJNZ    R7, DL2
        DJNZ    R6, DL1
                RET
                END