es such as VPDs (Virtual
Peripheral Devices) that have potential security implications.  Set
these carefully when simulating an unknown or untrusted circuit.
<ul>

<li><b>Enable the $tkg$command() system task:</b> If enabled, user
circuits can use the $tkg$command().  This system task can send a
low-level command directly from the simulator to the TkGate interface.
For normal circuits, there is seldom a reason to enable this feature.

<li><b>Enable the $fopen() system task:</b> If enabled, user circuits
can