K1   EQU  P3.7
LED  EQU  P0.7
STEP EQU  P2.6

       ORG 0000H
       AJMP MAIN
       ORG 0030H
MAIN:  SETB    STEP
       SETB    LED
KEY1:  SETB    K1                    ;將P1.0置1
       JB      K1,   KEY1            ;有鍵按下P1.0=0
KEY11: ACALL   DELAY                  ;延時，防止抖動
       SETB    K1
       JNB     K1,  KEY11            ;鍵是否釋放
       CPL     STEP
       CPL     LED                   
       AJMP    KEY1

DELAY:  MOV R5,#1     
DELAY1: MOV R6,#0FFH
DELAY2: MOV R7,#0FFH
DELAY3: DJNZ R7,DELAY3
        DJNZ R6,DELAY2
        DJNZ R5,DELAY1
        RET

        END