Configuration Dialog - Add Unit Button
Pressing this button adds a new device to the system. This brings up the Add device dialog.
You can choose the device type, controller number, and unit number. If the type of the device is DISK, the media edit is where the file name is shown. You can press the Browse button to select an existing file, or you can press Create to create a new file to hold a virtual disk.
You can press OK to add the new device or Cancel to abort the add.