"A combination of technologies, some off-the-shelf, some rare and esoteric, and some cooked up by Rokeby himself. Initially, in 1982, much more of the system was homemade. His circuitry, designed to speed up the response of the sluggish Apple II, was still not fast enough to analyze an image from an ordinary video camera, so he built his own low-res device: a little box with 64 light sensors behind a plastic Fresnel lens. But Very Nervous System has been evolving for 13 years, during which time the world has seen any number of technological revolutions. So Rokeby now has a lot more store-bought components incorporated into the system: it can handle a Mac Quadra and real video cameras, via sophisticated "Max" software from Paris."