Man-computer graphics for computer-aided design

This paper reviews the history, concepts, state-of-the-art, and future directions of the use of man-computer graphics for computer-aided design. Computer-aided design is based on a real-time graphical dialogue between the man and the computer in which the man draws on a display by means of a "light pen" or other input device. The computer "understands" the picture, makes calculations based on it, and presents the results pictorially to the user for his approval or revision. This man-computer graphical conversation has been made possible by recent advances in the speed of the digital computer, time-sharing programming, computer-driven display technology, and graphical input devices. The light pen is the most commonly used graphical input device, but keyboards, joysticks, flat matrix arrays, and other devices are also used. The programming state-of-the-art is a limiting factor in the implementatation of graphical computer-aided design; much work remains to be done in systems programming, efficient time sharing, list structure concepts, file organization, and memory protection. A number of experimental equipment configurations in use in various laboratories are cited and the hardware state-of-the-art is reviewed. Several experimental and production applications of computer-aided design evolved in a large aircraft company are described and illustrated, by display photographs. These applications relate to structural analysis, dynamics, information retrieval, accounting, and numerical control tape preparation. For the future, advances are required in improved man-computer communication, techniques to permit the operation of displays at great distances from the central computer, and methods of inputting existing drawings into the computer in a meaningful form.