Schematic generation with an expert system

A study of schematic generation by a knowledge-based system (KBS) is reported. Schematics must demonstrate features (continuity of signal flow and logical clustering) of a design while remaining simple (few turns and crossings). Algorithmic and manual techniques deal poorly with the multiple conflicting objectives. A successful switchbox router in a KBS suggested the same approach to schematic generation. Schematic generation in a KBS still needs to be partitioned into subproblems to make is tractable. Subproblems include ordering of symbols and the placement of nets (i.e., routing). The ordering of symbols in the direction of information flow is based on a precedence augmented with a rule-based component which recognizes cycles and breaks them intelligently. A heuristic length-based ordering in the other direction tries to minimize crossings. The KBS paradigm is particularly applicable to the routing steps