ORG  0000H
        LJMP  MAIN
        ORG  0100H
MAIN:   mov  sp,#60h
        MOV   P1,#00H
KEY:    MOV  P2,#0FFH
   	MOV  A,P2
	CPL  A
	ANL  A,#0FH
	JZ   KEY
	LCALL  D10MS
	MOV  A,P2
	CPL  A
        ANL  A,#0FH
        JZ  KEY

        JB  ACC.0,K1
	JB  ACC.1,K2
	JB  ACC.2,K3
	JB  ACC.3,K4
K1:  	MOV  A,#20H
        MOV  P1,A
	LCALL  D10MS
	RR  A
        MOV  P1, A
        LCALL  D10MS
	RR  A
	MOV  P1, A
        LCALL  D10MS
       ; JB  P2.0, K1
	;LCALL  D10MS
        JNB  P2.0,K1
        LJMP   EXIT
K2:     MOV  A,#01H
        MOV  P1,A
	LCALL  D10MS
	RL  A
        MOV  P1, A
        LCALL  D10MS
	RL  A
	MOV  P1, A
        LCALL  D10MS
        JNB  P2.1,K2
        LJMP   EXIT
K3:    MOV  A, P1
        CPL   A
        MOV  P1,A
       LCALL  D10MS
       JNB  P2.2,K3
       LJMP   EXIT
K4:    MOV  P1,#0FFH
       LCALL  D10MS
       JNB  P2.3,K4
       LJMP   EXIT

D10MS: MOV  R7, #10H
DS1:   MOV  R6, #0FFH
DS2:   DJNZ  R6, DS2
       DJNZ  R7,DS1
       RET
EXIT:
       MOV  P1,#00H
       LJMP   KEY
       end