How can we better design computer chips? This paper identifies fundamental modeling concepts for capturing the semantics of VLSI CAD design objects and versions. It emphasizes design objects with both an interface description and an implementation description. The modeling framework is built upon the idea of molecular objects, which enable a database entity to be represented by two heterogeneous sets of records. Furthermore, versions of design objects have a common interface but differ in their implementations. A provisional set of user operations on design objects, consistent with these modeling concepts, is also defined. It is shown that capturing the semantics of VLSI CAD design objects and versions in terms of molecular objects is an improvement over older versions. The modeling framework that we present has been found useful for investigating physical storage techniques and change notification problems in version control.
This article's focus on the semantics of VLSI CAD design objects and versions aligns with ACM Transactions on Database Systems' concentration on the newest advancements in database theory, technology, and applications. It offers a useful framework for version control and physical storage that goes well with the journal's coverage of database data models.