# SIM: Simulation Modes

There are three different modes you can toggle when running a simulation. By default, the Trace and History are enabled, and Fast Mode is disabled.

### Toggle Trace

When Trace is enabled, the Trace output will function as described in the Trace tab of the States Pane. When Trace is disabled, it will not be shown in the Trace tab or in the Trace Viewer.

### Toggle Fast Mode

By default, this mode is disabled. This is also known as Slow Mode. When simulating several events simultaneously Slow Mode pauses between each event to give the user time to view the changes taking place within the DES. This time delay can be changed in the Dashboard tab. When you enable fast mode, no time delay is used and the simulation runs at full speed.

### Toggle History

When History is disabled, you can only run a simulation forward in time and cannot step back. This also disables the History View. Once History is disabled for a simulation, it cannot be re enabled.

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