;code by Dinhhuan
org   0000h
jmp   MAIN
MAIN:
SETB P1.0
MOV R7,#0D5H
MOV R6,#0H
JNB  P1.0,BU1
JB P1.0,BU2
BU1:
MOV A,R6
CPL A
MOV R6,A
MOV A,R7
CPL A
MOV R7,A
RET
BU2:
CLR C
CALL BU1
MOV A,R6
ADD A,#1
MOV R6,A
JC NHAN
ret
NHAN:
MOV A,R7
ADD A,#1
MOV R7,A
END