NOMAD: A printed wiring board layout system

Abstract

The NOMAD (Nonmodular Or Modular Automated Design) system provides computer-aided support for the layout of a wide range of printed wiring board designs. The system may be used to design both highly irregular nonmodular and more uniform modular printed wiring boards. The nonmodular boards usually contain numerous discrete and some digital components, whereas the modular varieties are almost entirely digital in nature. In order to guarantee flexibility and control of the layout process, the NOMAD system was implemented on a minicomputer-based interactive graphics terminal. The interactive graphics environment permits the NOMAD user to guide the PWB layout process through steps such as component placement and interconnection routing. Through the use of interactive display techniques and both heuristic and algorithmic computational aids, the user can complete the layout with NOMAD in a considerably shorter time than with alternative methods. Although the focal point of the NOMAD system is at the graphics terminal, telecommunication facilities are utilized to access large compute-bound component placement programs. Aside from the placement, all other design activities, including automatic routing aids, occur at the graphics computer. Once a printed wiring board layout is complete, facilities are available through NOMAD to obtain a full array of design documentation. This documentation includes artmasters for printed wiring board fabrication, an assembly drawing, a stocklist, schematic drawings, and a drill table.The NOMAD system has been operational since April, 1974. Improvements and enhancements are being made continually in an effort to further increase the cost effectiveness of the system.