Use an old computer for a lab bench or just have one sitting around? Chances are good that if it’s more than a few years old, it’ll have a parallel port on it. If you also run Linux and want to play around with I/O you should take a look at this project. It’ll show you how to hook up a standard 16×2 LCD character screen to your parallel port, create drivers for it, and then control it using redirects to /dev/my_lcd. Very cool!