Within the field of Design Automation, the term “data base” has generally lacked a precise definition, but it usually describes a system which integrates, organizes, and controls a large amount of data. In this paper, we will examine two approaches to implementing a CAD data base - an MIS-type system where one logical and one physical representation of data exist, and an alternate system where one logical data base structure is physically utilized many times. We will discuss the advantages and disadvantages of the second approach, which we implemented at Raytheon.

The concept of a Computer Aided Design (CAD) database (Figure 1) has been discussed for many years, however, during the course of actually implementing such a data base at Raytheon, we found that many critical concepts are hidden in Figure 1. We will discuss these concepts by analyzing the types of information in a CAD data base and by analyzing the “flow” of this information.