Character generation from resistive storage of time derivatives

Abstract

Recent advances in man-machine communication have stimulated increased interest in techniques and special circuits that generate characters, for graphical and alphanumeric Cathode-Ray-Tube (CRT) display terminals, at the display site. The primary advantage in employing such local character generation is compression of the data that is required to store and communicate a character from the computer to the display---a single binary word of length n is all that is required to instruct the character generator to display one of 2n possible characters. The primary disadvantage of local character generation is display cost, for it is generally considerably less expensive to generate characters from a longer sequence of more elementary commands---for example commands that cause the CRT beam to move right, left, up or down by a minimum resolvable increment. Besides these conflicting costs of data storage and transmission versus local-display generation, several other less tangible criteria such as character stability and fidelity (aesthetics), are instrumental in the design and evaluation of a local character-generation approach.