A Simple Display for Characters and Graphics

Abstract—The display system, named MODEL T, accepts coded digital data from a voice grade telephone line and displays graphical and alphanumeric information on a direct-view storage tube. Since a storage tube is used, no local refresh is required to maintain the display. The essential virtue of the MODEL T is the combined graphic and alphanumeric capability in an economic design. The MODEL T operates in an incremental vector mode, each vector being described by 7 bits. A vector calls for the display to move the beam from its present location along one of eight directions, a distance of one of eight permissible lengths, with the beam either on or off. A vector is drawn as a series of dots which are written at a uniform rate. A minimnum command structure is provided. The MODEL T draws 240 vectors per second (over a 2400-baud telephone link) and can thus display rather complicated patterns in a matter of seconds. Normally alphanumeric symbols are formed from a sequence of vectors under software control; a character generator can be added for increased speed. The MODEL T, without a character generator, can write text substantially faster than a TELETYPE.