ORG    000H
AJMP    MAIN
ORG      0030H
;************ CHECK KEY********
MAIN:
MOV P3,#0ffh
mov a,P3
XRL a,#0ffh
JZ MAIN      ;NO KEY PUT DOWN   
MOV  A,P3
XRL A,#0FEH
JZ  LOOP1   ;KEY1 PUT DOWN
MOV  A,P3
XRL  A,#0E7H
JZ  LOOP2    ;KEY2 PUT DOWN
MOV  A,P3
XRL  A,#0EFH
JZ LOOP3    ;KEY3 PUT DOWN
MOV  A,P3
XRL  A,#07EH
JZ  LOOP4  ;KEY4 PUT DOWN
AJMP MAIN
;*******************
LOOP1: 
MOV   R0,#08H
MOV   A,#07FH
LOOP11:
MOV  P1,A
MOV  P2,A
RRC  A
CALL  DELAY 
DJNZ R0,LOOP11
RET 
;********************   
LOOP2: 
MOV   R0,#0AH
MOV   A,#0FFH
LOOP21:
MOV  P1,A
MOV  P2,A
RLC  A
CALL  DELAY 
XRL A,#07FH
DJNZ R0, LOOP21
RET   
  
LOOP3: 
MOV R0,#0AH
LOOP31:
MOV  A,#0AAH
MOV  P1,A
MOV  P2,A
CALL  DELAY 
RRC  A
DJNZ R0,LOOP31
RET 
;************************
LOOP4: 
MOV   R0,#0AH
MOV   A,#0FFH
CLR  C
LOOP41:
MOV  A,#055H
MOV  P1,A
MOV  P2,A
CALL  DELAY 
RLC A
DJNZ R0,LOOP41
RET 
;**************************
DELAY :MOV   R5,#10h 
DELAY1:MOV  R6,#50h
DELAY2:MOV   R7,#050h
DJNZ    R7,$
DJNZ   R6,DELAY2
DJNZ   R5,DELAY1
RET
END