The Digigraphic Display Program for the DX-1 Computer System

Summary

This document, authored by John T. Gilmore, Jr. of Charles W. Adams Associates, describes the "Digigraphic Display Program" (DDP) for the DX-1 computer system, presented at the 1963 Digital Equipment Computer Users Society meeting.

The DDP is a specialized software tool designed to enable users to create, manipulate, and store complex graphical and alphanumeric drawings directly on a buffered display scope. By utilizing a light pen, a push-button control panel, and specialized software routines, the program allows users to draft points, lines, circles, arcs, and freehand or third-degree curves. Key features include:

• Geometric Representation: Drawings are stored internally as "Entity Tables," allowing for efficient digital management.
• User Control: Users can manipulate entities through various modes—specifically "Pick" (for selecting and referencing existing drawing elements) and "Sketch" (for active drawing and movement).
• Advanced Drafting Tools: The system supports constrained drawing (horizontal, vertical, and protractor-based), grouping of entities for bulk movement/rotation/reflection, and the generation of dimension lines and alphanumeric notes.
• System Integration: The DDP operates on a 4K PDP-1 computer integrated with hardware such as a Bryant magnetic drum, a flicker-free display processor, and Itek light-pen equipment.
• Scalability: The program provides robust scaling and magnification features, allowing users to zoom into specific details or view the drawing as a whole.

The document emphasizes that the DDP serves as a flexible, modular foundation that can be expanded or tailored by users to meet specific drafting or engineering needs.