The infamous VMM32.VXD tweak

The Windows\system\VMM32.VXD is a compressed file which contains a set of VxD (Virtual device Driver). The set of VxD-files are selected specifically for your machine so you shouldn't use the VMM32.VXD from a different computer.

The response time of Win9x should be increased by extracting the same set of VxD-files from the Win9x-CDROM's CAB-files and place them in the directory C:\Windows\System\Vmm32. This will make Windows use the decompressed VxD-files instead of those placed in the VMM32.VXD.

You can see if a VxD file for a device is compressed into the VMM32.VXD, by starting the Device Manager and select Driver Details for a device, then you might see something like "C:\Windows\System\vmm32.vxd (configmg.vxd)"

You can go to this registry key to find all the files which are inside the vmm32.vxd:

[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \VMM32Files]

Note everyone, who thinks that they know something, says that you will gain nothing from it and actually the compression of VxD files into VMM32.VXD was done to improve boot time. But at the same time there is a lot of people who have tried it and said the opposite.

Note the VMM32.VXD placed in the Win9x-CDROM's CAB-files is just a skeleton files and is not containing any VxD files.

Note the VMM32.VXD is usually loaded in the conventional memory area if no room is available in the UMB. If free conventional memory is important, then check How to get a larger UMB.

Related Use extract.exe to restore a system file
Related Use of the System File Checker in Windows 98
Related Use of the System File Protection in Windows Me

More Info MS KB174018
More Info MS KB194679
More Info MS KB195164
More Info MS KB296579

Credits InfiniSource.com

Updated: 26 September 2007

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