I have written my C code using uvision and tested it on the MCB517AC evaluation board. It works perfectly. But, when I use the .hex file( being created by uvision ) and program it into 89C52, through a Dataio Universal programmer, it works no more. Please help! The hardware setup for my 89C52 is a crystal 12 MHz connected to pin 18, 19. Pin 18 and 19 are also connected to a 27pF capacitor each, before being grounded. A push-down button and a 10uF capacitor is installed between 5V and the reset pin.
I have finally discovered the culprit of my failure. It is the EA(External Access) pin of AT89C52. In the past, I did not connect this pin at all!!! I should have connect it to a high so that it will use internal ROM. Thanks for all who have tried to help in any ways!!!