Checking the CD-ROM box will define the device as a CD-ROM.  Image files with an .iso extension are automatically assumed to be CD-ROM devices.  A zero-unit configuration includes one raw CD-ROM or DVD-ROM device.  Avanti mounts a configured CD-ROM read-only. Separate Avanti processes can reference one host optical drive, but Avanti does not coordinate their media state or concurrent access; this arrangement is not qualified for 5.1.0. Prefer a separate image path or copy for each emulator when concurrent access matters.