lamp Multiple segment alphanumeric displays are nearly as old as the use of electricity. A 1908 textbook describes an alphanumeric display system using incandescent lamps and a mechanical switching arrangement. Each of 21 lamps was connected to a switch operated by a set of slotted bars, installed in a rotating drum. This commutator assembly could be arranged so that as the drum was rotated, different sets of switches were closed and different letters and figures could be displayed. The scheme would have been used for "talking" signs to spell out messages, but a complete set of commutator switches, drums and lamps would have been required for each letter of a message, making the resulting sign quite expensive. Cold-cathode neon A few different versions of the fourteen segment display exist as cold-cathode neon lamps. For example, one type made by Burroughs Corporation was called "Panaplex". Instead of using a filament as the incandescent versions do, these use a cathode charged to a 180 V potential which causes the electrified segment to glow a bright orange color. They operated similarly to Nixie tubes but instead of the full-formed numeric shapes, used segments to make up numerals and letters. Examples See also Seven-segment display Eight-segment display Nine-segment display Sixteen-segment display Dot matrix display Nixie tube display Vacuum fluorescent display References External links Display technology