I did this project mainly as a learning experience. It's sole purpose is to send and retrieve data over to and from my PC's parallel port. The data is stored in two buffer registers, one for input and one for output. The contents of the buffer registers are displayed in octal on the two LED displays above the keypad.
The inputs for the input register and the outputs of the output register are connected to the two 9 pin D-sub connectors on the bottom edge of the board, so that I can transmit data to or from an external device using separate input and output buses. The contents of the input register may also be edited with the keypad, one digit at a time.