Windows 2000 legacy OS compatability mode revealed

A not very well-known option of Windows 2000 is the compatability mode option. Not enabled by default, this option allows you to lie to an application and make it think that you are running it under a different operating system. (This was an obscure option that was available in Windows 95 using the MKCOMPAT.exe command). This option allows you to tell the application that it is running under Windows 95 or NT4.0 SP5.


To enable this feature, you must have installed Windows 2000 SP2. Once this is installed, do the following:

Click Start --> Run --> type: regsvr32 %systemroot%apppatchslayerui.dll

You will receive a message that the DLL has been successfully registered. The compatability mode option is now available for use.


Different from the Windows 95 MKCOMPAT, the Windows 2000 compatability mode option only operates on a SHORTCUT. So, for example, if you wanted to run application C:WINDOWSWINFILE.EXE under windows 2000 and make the OS think that Windows 95 is running it, do the following:

  1. Enable Win2k legacy support by registering the SLAYERUI.DLL file.
  2. Create a shortcut to C:WINDOWSWINFILE.EXE and place it on the desktop.
  3. Right click the newly created shortcut and click properties.
  4. Select the "COMPATABILITY" tab, check the "Run in compatability mode" checkbox and select the OS that

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  1. you want to run this application under (in this case, "Windows 95 compatability layer."

This was first published in December 2001

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