Abstract: A placement tool that may import and export cell substitution and/or cell selection lists. The cell substitution and/or cell selection lists may be used by the placement tool to substitute and/or modify the placement design database, rather than the original schematic or behavioral database. This may eliminate the need to re-synthesize the circuit design during each design iteration. The present invention further contemplates providing a reset feature which may reset the circuit design database to a previous state, if desired.

Abstract: A method and apparatus for selectively viewing nets within a database editor tool. The present invention provides four primary features for selectively viewing nets. First, the present invention contemplates selecting a number of objects, and viewing only those nets that are either driven from or received by the selected objects. In a preferred embodiment, the number of objects are placed objects within a placement tool. Second, for those nets that are selected, and that are also coupled to un-placed cells, the present invention contemplate providing fly-wires from the corresponding selected objects to a predetermined location representative of an approximate expected location for the un-placed cells. Third, the present invention contemplate providing a vector filter which may permit only vectored nets with a selected bus width range to be viewed.