When run in the interactive mode the simulator simulates the operation of the circuit currently visible in the editting window. If the visible circuit is a subcircuit of another circuit, then the simulator will simulate the entire circuit the subcircuit is in.
The simulator can be visible or not when running. To make it visible, select the Show item in the Simulator menu; select the Hide item in the Simulator menu to hide it. When first shown, the signal trace area is not displayed. To see it, drag the divider between the editting window and the simulation window up.
If the simulator is not visible when started (i.e., via the menu), then a yellow simulator bar will appear below the editting window. It will show the current state of the simulation (e.g., running, stopped) and the number of time units that have been simulated so far. To stop it prematurely, use the stop item from the Simulator menu.
A visible simulator window allows more control over the execution of the simulator (e.g., stepping by various time amounts) and allows you to see a trace of various signal and element values versus time. Simulation can be started via the start button, paused via the pause button, resumed via the resume button, stopped via the stop button, stepped by some number of time units via the step button, and animated via the animate button.
The Start button only works when the simulation is stopped. If it is being stepped or has been paused, clicking on Start has no effect. However, a stepped or paused simuation can be resumed, or a paused simulation stepped.
When the simulation stops, finishes a step, or pauses, wires that have the value 0 are shown in black and wires that have non-zero values are shown in red. Signal traces are also updated. The actual value on any wire can be displayed in the cyan message area above the circuit by moving the cursor over the wire. Register values can be seen analogously. The contents of a memory element can be displayed by right clicking on the element and picking the View Contents item from the menu that pops up.
Signal traces can be printed by clicking on the Print button. A dialog box will appear in which you can specify various printing parameters.