Electric has a built-in simulator, Stanford's IRSIM, which uses RC models to accurately simulate transistors at a gate-level. IRSIM is not packaged with the standard Electric distribution. To obtain it, you must get the additional "plugin" JAR file from Static Free Software (see Section 1-5 for instructions on installing plugins).

To simulate the current cell with IRSIM, use the IRSIM: Simulate Current Cell command (in menu Tool / Simulation (Built-in)). After issuing this command, a waveform window will appear to control the simulation (see Section 4-12-1 for more). To generate an input deck for IRSIM without running the simulator, use the IRSIM: Write Deck... command. To simulate an IRSIM deck (that is, simulate the file, not the circuit), use the IRSIM: Simulate Deck... command. Note: if these commands do not appear in the menu, then IRSIM has not been installed.

Since the IRSIM engine is running inside of Electric, you can place stimuli on the circuit and see the results immediately (also described in Section 4-12-1). Note that the command to save stimuli (Save Stimuli to Disk... of menu Tool / Simulation (Built-in)) writes an IRSIM "command file" which can be edited by hand.

The Simulators Preferences (in menu File / Preferences..., "Tools" section, "Simulators" tab), offers some controls for IRSIM. The general controls at the top are discussed in Section 4-12-1.

IRSIM uses a parameter file to describe timing and parasitic information. Two of these files come packaged with Electric ("scmos0.3.prm" and "scmos1.0.prm"), but you can create your own and tell IRSIM to use it. In addition to the parameter file, you can select the simulation model that IRSIM uses. The default is a RC model, but a Linear model is also available.

Advanced users who edit their own command files may enter specialized IRSIM debugging commands. These commands depend on a set of flags to determine the type of debugging to do. Checkboxes in the "IRSIM Debugging" section control these debugging flags.

The bottom section has two miscellaneous IRSIM controls.

- "Show IRSIM commands" requests that the system display the command file instructions as they are applied during simulation.
- "Use Delayed X propagation" does less conservative, but potentially more accurate calculation of the time required to propagate an undefined (X) value in the circuit. This improved propagation delay calculation has been shown to be effective in asynchronous circuits.