Registry Home > Tips and Tricks > Configuration Files > MSDOS.SYS

Allow Booting to the Previous Operating System (Windows 95/98/Me)

If you installed an upgrade version of Windows, you can normally press F4 to boot your previous version of Windows. This option can be disabled.

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Change the attributes for MSDOS.SYS so it is not 'Read Only', MSDOS.SYS is found in the root directory of your C:\ drive. Open the file using Notepad or another text editor (not Microsoft Word or any word processor).

Change the value of 'BootMulti=' to 'BootMulti=1' for F4 enabled or 'BootMulti=0' for disabled.

Changes will take place on the next reboot.

Registry Settings
Value Data: BootMulti=1 (default)

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Disclaimer: Modifying the registry can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from modifications to the registry can be solved. Use the information provided at your own risk.

Last modified: May 12, 2002