The GT40 is a low-cost, high-performance graphic display system which operates through a powerful general-purpose computer. The GT40 is designed for applications which require both visualization and computation. The system can display either alphanumeric information or graphic inromation such as drawings, diagrams, or patterns. It is especially valuable for displaying dynamic, fast changing information such as wave forms. Designs and layouts can be plotted in minutes instead of hours, then instantly modified using the light pen. Designers are free to concentrate on layout while the system handles the calculations. And, the computer can easily monitor a check list to make sure every detail is included.