SPAR: a schematic place and route system

An approach to the automatic generation of schematic diagrams from circuit descriptions is presented. The heuristics that make up the system are based on two principles of schematics readability: functional identification and traceability. SPAR's generation process is broken into five distinct phases: partitioning the netlist, placement of components on the page, global routing, local routing, and the addition of I/O modules. All phases of the generation process use a two-dimensional space management technique based on virtual tile spaces. The global router is guided by a cost function consisting of both congestion and wirelength estimates. The local router uses a constraint-propagation technique to optimize the traceability of lines through congested areas. The data structures and algorithms used allow the system to support incremental additions to the schematic without complete regeneration. A technique for evaluating the quality of schematic drawings is described and applied to the present results.<
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