The IsSpice4 Simulation Control panel is used to enable a number of interactive features. For example, runs can be paused then resumed. During pause, component values or parameters - including special expressions, or as function of other components' change - are assigned without schematic interaction. The simulation is automatically restarted and includes updated results with progressing real time waveforms. Modify any single parameter, or group of parameters. Significant gain in speed is achieved because each simulation run is based on data preserved from previous runs (e.g., nodal equation matrix preserved), thus eliminating at least 95% of the overhead in simulation time.

Shown below, the Stimulus button was used to select a parameter variation dialog for c1 (capacitance) selecting "Always" causes a simulation to be run each time the parameter is changed. The piano-like buttons vary the parameter in decade sensitivity in either increasing or decreasing value. Using this dialog, the probe capacitance can be trimmed to just the right value by viewing the overshoot/undershoot as the value of c1 is varied. The persistence value in the Simulation Control dialog allows the user to view the results of previous simulations, up to the number specified.