SCSI virtual devices are used to emulate advanced disc images with special signatures (RMPS, SafeDisc, SecuROM, LaserLock). So now you can use DAEMON Tools Lite to emulate backup images of your protected discs. See Preferences\Advanced tab for available options.
To create new SCSI virtual device:
Click 'Add SCSI Virtual Drive' button.
SPTD driver will be installed (if not installed already). Click 'Install'.
Wait for SPTD to be installed.
Save all important data and click 'Reboot now' (1). Also you can reboot later (2).
Wait for system to update virtual devices after reboot.
Your new virtual SCSI device is ready to use. It supports all base functions plus advanced emulating capabilities — see Preferences\Advanced tab.