Control 8 Electrical Devices With Your Parallel Port

Michael Williamson writes "A PC parallel port can provide 0 or 5v on 8 pins, individually controllable. This can be used to directly drive LED lights, or with the addition of an external power supply, some switching transistors, and some relays, control 8 higher-powered devices. I've written a handful of example programs that drive a homemade 8-LED display in amusing ways."