Keywords computer graphics, Bell Telephone Laboratories, Graphic 1, circuit design, electronic light pen, programming, visual representation, communication satellites, sound waves, artistic ...

Always wanted to use a light pen but didn’t have a computer. When I finally got a C128, (BASIC 7 even included the PEN command!) I couldn’t really afford the commercial light pen versions.

Light pens were originally invented for use with vector displays, long before bitmapped raster displays were feasible. On a raster display, the light pen triggers on the portion of the “display ...