"In 1972 a new system named PLATO IV was ready for operation. The PLATO IV terminal was a major innovation. It included Bitzer's orange plasma display invention which incorporated both memory and bitmapped graphics into one display. This plasma display included fast vector line drawing capability and ran at 1260 baud, rendering 60 lines or 180 characters per second. The display was a 512x512 bitmap, with both character and vector plotting done by hardwired logic. Users could provide their own characters to support rudimentary bitmap graphics. Compressed air powered a piston-driven microfiche image selector that permitted colored images to be projected on the back of the screen under program control. The PLATO IV display also included a 16-by-16 grid infrared touch panel allowing students to answer questions by touching anywhere on the screen" (Wikipedia article on Plato (computer system), accessed 12-30-2009).