Advances in systems technology are creating the need for alphanumeric displays and component technology to satisfy this need. The field of alphanumeric displays covers applications from the single character lift indicator to the thousand-plus character computer read­ out. A survey of the state of alphanumeric displays helps the user of display devices to make a choice, for a particular application, between the various devices available now or in the near future. It is essential to consider the circuits and the display device together in order to obtain a clear picture of the economics of the different techniques. In general, a display module is controlled by binary input signals at normal logic pow­ ers and may be subdivided into five basic elements: 1) data memory, 2) character generator, 3) driving circuits, 4) scanning circuits, and 5) display device. The data memory is essential to make the display module independent of the system. Normally, this will be an electronic memory, but in some cases, the display device will have an inherent memory. The character generator must perform two functions: 1) convert the binary code to a 'lout of n' form to select the chosen character out of the on' available, and 2) create the character format, although in some cases this is inherent in the display device.