Hi friends: I need your help again. I have used Keil c51 to compile my program which has past emulator and simulator test. Right now I am burning AT89C52 chip. In my code I want port P1 to be high, but every time I always get opposite situation. Few pins of P1 port are randomly low. What is wrong, Should P1 port be high after resetting? The worst thing is my chip can not receive interrupt even I have set EA, EX1, EX0, IT0 and IT1 to high in my code. Do you have any idea about that? Would let me share your ideas? Thank you and Best Regards.