I've since found some good info on the web about this subject. The following URL is a good place to start and has some good links: http://ourworld.compuserve.com/homepages...ybinfo.htm

ATMEL and Phillips also both have some documents on how to interface their MCU's to PC AT keyboards. (Follow the URL)

It seems that the PC AT Keyboard puts out a 5v TTL data and clock signal. The interface is as simple as connecting the clock line to an MCU interrupt and writing an ISR to read the data line.

Of course the keyboard protocol is another story!