START1:
    CLR P2.5;
    CALL DELAY
    SETB P2.5;
    CALL DELAY
    JMP START1
DELAY: MOV R5, #25
D1: MOV R6, #100
D2: MOV R7, #100
    DJNZ R7, $
    DJNZ R6, D2
    DJNZ R5, D1
    RET
    END