Axel Berger wrote:

It's a file that is dynamically created by windows when windows is
installed and also when new hardware is detected. It's pointless
to compare file-size and file-date between two different vmm32.vxd
files.

If that's so, don't I lose all the entries Windows has already made
there?

There is no modification or interference with your registry in relation
to changing the vmm32.vxd file.

I *believe* that when win-98 is first installed, it uses the default
vmm32.vxd as-is, and any additional virtual device drivers that are
specific to your system are placed in the /vmm directory and are not
incorporated into the default vmm32.vxd file. But under some
circumstances Win-98 can rebuild vmm32.vxd and incorporate those extra
..vxd files from the /vmm directory, and that's why you'd end up with a
different vmm32.vxd file than the default version from the CD.

For example, the default VMM32.VXD file on the win-98se CD is 464 kb in
size, but my actual VMM32.VXD in c:\windows\system was 907 kb before I
renamed it and replaced it with the modified file, which is 903 kb in
size.

Again remember that if you first rename your existing VMM32.vxd (to,
say, VMM32.vx_ or VMM32.vxd.old) and then copy the new VMM32.vxd to
c:\windows\system (and also copy the file vmm.vxd to
c:\windows\system\vmm32) and if Windows doesn't boot, then simply
re-start in DOS and restore your original vmm32.vxd (and delete the
vmm.vxd that you put in c:\windows\system\vmm32).

Here's more info about VMM32.VXD

=========================
Win9x installation of VMM32.VxD

It is accepted that VMM32.VxD is initially a basic file which is built
up with additional VxDs (required specifically by that PC's own
components) during Win98+ installation. Those additional VxDs are then
accessed from within VMM32.VxD.

However that initial VMM32.VxD file is not an empty skeleton waiting to
be filled. It is a substantial 475,084 bytes on the CDs of both Win98
(Win98_48.cab) and Win98SE (Win98_54.cab). This is the size prior to
installation. It contains many components that will be used by Win9x and
is added to at the time of Win98, 98SE, or ME installation.

After Win9x installation, any additionally installed VxDs will be placed
in \Windows\System\VMM32. These will take priority over any previous VxD
within VMM32.VxD. The size of VMM32.VxD in the Windows\System directory
after installation will vary from system to system. It will now be
substantially (perhaps twice) larger than the CD version and should
carry the date of your last installation of Win9x. The increased size is
partly the result of specific VxDs being added during Win9x
installation.

To view the contents of the 'new' VMM32.VxD run RegEdit and go to the
Key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l/VMM32Files
where the right pane shows all the files that comprise VMM32.VxD.

It is now said that ALL the VxDs required for your own system will be
present, though you could check your own Registry just to make sure.

http://www.thpc.info/upd/vmm32.html
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