This video tutorial will show you how to take an old computer keyboard and use its circuitry as a physical computing input device. Once you have this device, you can then use it to interface with programs that you write using software such as pure data processing, MAX/MSP, and Ableton Live to name a few. What you are doing is replacing the switches within your keyboards with others for input devices. Make sure the interface is plugged in when you are testing but it's probably a good idea to unplug it when you are soldering your switches. Watch this video circuitry tutorial and learn how to modify your own computer interface.