That's its description. Why would you need an emulation layer between
the real device and the application trying to access that device? Yes,
it does provide drive emulation, like MagicDisc, VirtualCD, or Virtual
CloneDrive, but it uses its SPTD driver to hide characteristics of real
drives. The SPTD driver is not a requirement of emulating an optical
drive. It has a different use.
It was (maybe still is) included with the Alcohol 120% product. At some
point (I have not bothered with DT for a long time due to crashes caused
by it), it looks like their installer now defaults to NOT including the
SPTD driver (you will find it listed as SPTD<randn> where <randn> was a
random 4-digit number in trying to hide it from software detection by a
specified driver name). That was not true in the past. So obviously
SPTD is *not* required for DT to function as a drive emulator. So what
was/is its purpose? SPTD was a system driver for direct access to
optical devices. You do not need that for just a drive emulator. SPTD
was needed for the subversive intent of the product: unprotecting what
was protected. It would try to hide or mask out the tricks used by a
few copy protection schemes.
In the past, in the right-click context menu for DT's tray icon, it had
several options to thwart copy protection on discs. I only remember the
SecuROM context menu entry for when you wanted to enable that copy-
protection voidance method. You do not need that if your purpose is to
load legit and unprotected ISO images of discs.
After installing Daemon-Tools with SPTD included, load the DT program.
Click on the gear icon to get at Preferences. Click on the Advanced
button in the left pane. See those protection schemes that SPTD is used
to try to thwart (RPMS, SafeDisc, SecuROM, LaserLock)? Where are those
copy protection schemes most employed? For games, that is where. The
idea was that you could use an emulated copy of the game's disc so you
did not have to keep inserting the disc into the real optical drive, and
DT would try to thwart the copy protection scheme so the game could not
find or got lied to that the real disc was in the real drive. I do not
know how effective was DT's copy-protection hiding since the games I have
played detected it was not a real optical drive, saw it was an emulated
drive, and refused to load.
With SPTD included in the installation, you have to reboot your host so
the new system driver gets used. If you omit SPTD from the installation
of Daemon-Tools then no reboot is needed. When you omit the SPTD
driver, the Advanced config settings still show the voidance methods for
various copy-protection schemes but they are all dimmed (disabled).
Without the SPTD driver to lie about the characteristics of the drive,
DT cannot offer to thwart the copy protection.
Back when DT was in its hayday, its users were not really trying to lie
about why they were using this program. They knew why they had it
installed. At that time, there were few drive emulators that worked
well and that is why I got it. I just left my game discs in the optical
drives (I'd add as many as I wanted for how many discs I wanted to leave
mounted, or use a CD changer drive) rather than try to use a
unprotection scheme that did not work very well (for me, that is). I was
using it before they tacked on the "Lite" moniker. Alas, it crashed too
often or even hung my host so I went to something else (e.g., Virtual
CloneDrive, MagicDisc). Eventually I just gave up on all of them since
they all seem flaky and instead I just keep a CD wallet in my desk's top
drawer for the discs I need most often.
If the OP included SPTD in the install of Daemon-Tools, and because this
system driver intercedes access to the optical drive, and because the OP
is reporting abnormal with that optical drive, you do not think it would
be appropriate to get rid of it (by uninstalling BOTH Daemon-Tools and
then following with the separate removal of SPTD) to make sure it was not
altering the behavior of the device? The SPTD driver requires a
separate removal since it will not uninstall when using DT's uninstaller.