Hi Frank.

The web sites regarding PC keyboard also say that the keyboard clock and data lines are open-collector pins. Therefore they suggest pulling it up to +5V via, say 4.7K resistor (I used this value).

Secondly, the delay I mentioned, 100 usec...its actually 217 usec. The reason is that when I started this project, I imported a header file from my previous project for which a macro was defined for 100 usec reload high and low byte. At that time I was using a 24MHz crystal. This time I used a 11.0592 MHz crystal. I forgot to change its value which was set to "-200" for previous application.

Now for your problem.

Are u using a PS/2 keyboard ??? I hope there is not a lose connection with the keyboard's +5V and ground. I also hope that you are using the right pin for monitoring "clock and data".

Are you using an oscilloscope to watch the clock ?? Try setting or clearing a port bit if any interrupt is received on the uC INT0. Also you can see the voltage on clock and data pins of keyboard. If not pulled-up, they will give you some voltage.

Regards
Aman