Is that a TI product, I am more familiar with the Microchip but usually the method is very similar. i.e. a 4x4 or 5x5 matrix is used using 4 input 4 output, an example can be found in the MicroChip site which will show the common methods used.
If you mean a PC keyboard, then I can't help you, you would need to get the serial protocol used, there must be web sites that would give this.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.