INTERACTIVE COMPUTER AIDED DESIGN SYSTEM

A computer aided design system which results in reduced operator fatigue, increased speed, and increased accuracy features a single workspace for inputting information, such as type of drafting exercise, graphic element or symbol, element position established either by element coordinate designation or cursor tracking and alpha/numeric keyboard-like entries. The system utilizes dual CRT screens, one, the graphics screen, for viewing the end product of the graphic design and the other, the function screen, for providing a single workspace for entering data. In one embodiment, input data either in the form of fixed format blocks or sequentially presented menus are displayed to the operator at the function screen so that he may select appropriate inputs with a light pen. Because all types of inputs are accomplished at a single workspace, the single workspace function screen avoids eye and arm fatigue so that the operator (i.e. draftsman or engineer) may comfortably and more accurately create the finished product with a minimum of eye, arm and mental operations. The advantages of the single workspace in terms of error reduction and fatigue reduction are complemented by displaying status messages at the function screen so that the operator need not look elsewhere to ascertain the accuracy or status of his input. The single workspace system requires that the operator only point as opposed to making other types of entries in order to create his design. In one embodiment a valid input is indicated by the lifting of the pen once a menu selection or pick has been established thereby to give the operator time to ascertain whether his menu pick is correct. Image reversal is also used to indicate the portion of the menu selected during the menu pick operation.