On Sat, 21 Jul 2012 16:59:59 -0500 "TheGunslinger"
Somewhat OT, but does Virtual PC support installation of any drivers at
all? I have an XP app I'd like to use. The app is said to run fine on Win
7, but the company didn't provide a Win 7 driver (for a USB device).
The hardware is generally emulated. Many things the guest OS thinks it is
doing, it is doing to "faked" hardware. The guest OS tends to be
"insulated", which limits some things it can do from a hardware
perspective. For example, a 3D game loaded in WinXP Mode, might
not work very well.
Some virtual machines, support "USB passthru", and that's about as
close as they come to something useful. Other interfaces that may
be directly supported, are things like serial ports (where COM2 in
the guest OS, can be mapped to COM1 on the actual hardware). So there
are a few things that "punch through" the sandbox, to the outside
world. Most virtual machine softwares, would likely allow you to run
a dialup modem for example (big deal...
)
Windows Virtual PC has *some* treatment of USB, but it is not
the same as the way VirtualBox does it. I think there may be
passthru for devices of USBStor class, on Windows Virtual PC.
That means, Windows Virtual PC only treats certain "classes"
of devices in a special way. Whereas VirtualBox redirects
USB traffic on specific VID and PID, at the USB packet level.
That makes the device "disappear" from the host OS, and "reappear"
in the guest OS, when VirtualBox is used. Microsoft chose to
not design their passthru in Windows Virtual PC that way,
for reasons that aren't clear (patents?).
Try running a copy of Everest in the guest OS, and get it to
list the hardware for you, and you'll see that the guest OS
sees a quite different environment, than the one your host OS
is seeing.
http://majorgeeks.com/download4181.html
For example, part of the emulated hardware in Windows Virtual PC,
will be a chipset from the 440BX era. It's done that way,
in the hope that more guest OSes support older hardware.
Which is true up to a point. Windows Virtual PC also presents
the networking interface, as a DEC Tulip ethernet chip. The
WinXP Mode OS installation, would install a driver for a DEC Tulip
chip, but the Windows Virtual PC software interprets what it's
doing to that "fake" chip, and routes the resulting packets
to the real hardware as part of its emulation.
The Windows Virtual PC also creates "I/O bottlenecks", when
doing its thing. By doing emulation of hardware, the interface
can be a lot slower than normal. For example, networking in
Virtual PC, might be limited to around 1.0 to 1.5MB/sec,
depending on the performance level of your CPU. There is
apparently a lot of manual data handling going on there.
Even if the Ethernet chip on your computer is GbE, attempts
by a guest OS to communicate through the Windows Virtual PC
emulation, should be slow.
When virtual machines first came out, a striking limitation,
was the speed they could update the screen. I remember some
older virtual environments I've used, where you could see
the guest OS drawing individual lines of pixels. Kinda like
a slowscan TV of sorts. At least that part of using virtual
environments, is no longer that slow. Things have improved
a lot, from how bad they were at first.
*******
Many people attempt to solve "missing hardware driver problems"
by using WinXP Mode and the underlying Windows Virtual PC. But
since the hardware environment is mostly emulated, with very
limited "passthru", it's not likely a driver problem
can be solved that way. VirtualBox has a more useful USB
passthru feature, that would make running say, a webcam
within VirtualBox work OK. But that might be as close
as you'd get. Windows Virtual PC doesn't do passthru for
USB for just *any* class of device. So the redirection
Windows Virtual PC does, is at the class level, rather than
the USB packet level.
You're better off, to start by investigating whether there
is a hack to get the WinXP driver to run in Windows 7 directly.
There are a few recipes out there for scanners for example.
It's best to Google the make and model number of the scanner,
and see what recipes are available.
Paul[/QUOTE]
Thank you, Paul! I learned a lot. The app I want to run has a USB
interface, but the driver won't install on Win 7. I'm slightly hopeful
that, being USB, I'll have a chance in virtual machine land. I'll give it
a try.