AppDisk is a ramdisk. What is a ramdisk? Its a piece of software
that lets you use some extra RAM memory as a really fast hard disk.
The disk will appear on your desktop just like any other hard disk,
and you can copy files to it just like normal. The only difference
between a ramdisk and a normal disk is that when you turn the power
off to your Mac, or restart, the contents of the ramdisk are lost.
This is one reason AppDisk has several options to automatically save
a copy of the ramdisk contents onto your hard disk.
The difference between AppDisk and most other ramdisk programs
(including the built-in one in the Memory control panel) is that the
AppDisk gets the memory for its disk from its own application memory.
Most ramdisks take memory away from your total system memory when
you start up, so you can't get that memory back without restarting.
To get the memory back with AppDisk, all you have to do is quit the
AppDisk program or remove the ramdisk from your desktop by dragging
it to the trash.