INTERF ACING INTERACTIVE CIRCUIT SIMULATION WITH STANDARD GRAPmCS FACILITIES

One oC the most popular and most powerCul circuit simulators, the SPICE-2G program Crom University oC California, Berkeley, is rather inefficient in interactive applications because oC its "batch-oriented" structure. SPICE-PAC is a package (or a set) oC subroutines which is Cunctionally equivalent to the SPICE-2G circuit simulator, i.e., it accepts the same circuit description and perCorms all the analyses which are available in the SPICE-2G programs, but also provides several extensions , e.g. , circuit variables, parameterized subcircuit expansion, and an interCace to libraries oC st.andard modules . Two immediate applications oC the package are: (1) interactive circuit simulation in which an interactive driver controls the simulation subroutines according to · user commands, and (2) circuit optimization in which an optimization package is interfaced with the simulation package by user-supplied subroutines that evaluate objective functions, constraints, etc. Recently, the package has been extended by an interface to graphics facilities . An implementation of this interface, compatible with both the CORE and GKS systems, is described, and some simple examples are given as an illustration.