Information models for connectivity in electronic design

Within the last years, the need for information modelling was more and more recognized in the world of electronic design. During 1990 both the EDIF European TSC Information Modelling Working Group (IMG) and the CFI Technical Subcommittee Design Representation (DR) have started to develop an information model for VLSI design representation data using the language Express. While the DR model is accompanied by a programming interface (PI) for tool access, the primary goal of the IMG model is to contribute to an understanding of the semantical concepts underlying EDIF. Both groups started their efforts with modelling connectivity. While the DR model is still restricted to that area, i.e. it covers approximately the EDIF netlist view, the IMG model also includes parts of other views, namely schematics and masklayout. This paper compares the connectivity parts of both models to find out, where they harmonize and in which points they differ. The comparison will show, that the basic entities (cell, view, port) are defined similar in both models, but that there are some differences in the connectivity of complex ports, which represent the concept of busses. Although there are differences in style and wording between the two models according to their primary goals, the commonly used language Express facilitates the comparison of the overlapping areas of both models. Thus it becomes clear, that the use of Express contributes to communication and clarification in the area of electronic design.