Patent US 6,131,081

A system for digital simulation of an electric circuit is disclosed. The system is event driven, and functions on a gate inversion principle, to stimulate an electric circuit. According to the gate inversion principle, any gates or gate arrangements in the circuit for which the input does not change are not simulated. A machine readable circuit description is generated which includes the gates and the gate arrangements for the circuit. Translation means creates data structures suitable for simulation of the circuit. Simulation means creates a program which schedules the simulation of only those gates or gate arrangements whose outputs change value during the simulation. According to the preferred embodiment, the simulation means uses only inversions of signals from individual gates or gate arrangements to perform the simulation of the circuit. Furthermore, the translation means includes means for removing any NOT gates from the circuit, and means for collapsing all homogeneous connections in the circuit. According to a further aspect of the invention, the translation means can include means for collapsing some heterogeneous connections in the circuit.