ATPS2Key is a sample implementation of the PS/2 keyboard protocol for ATmega microcontrollers. The implementation executes a partially incomplete translation of scancode-to-ASCII conversion. This part is intentionally stubbed, due to the number of regional variations out there.
ATPS2Key is released under the GNU General Public License, see this page for details.
The AVRStudio4 project can be downloaded here: atps2key-0.6.zip
Hook it up
Connect power pins to the keyboard (+5v/GND), and hook CLK to INT0 (PD0 on the ATmega128) and DAT to PB0.