In Windows 98, MSDOS.SYS is a hidden, read-only text file that incorporates all of the Windows 98 start-up switches.
To edit it, you'll first need to make the file visible:
1. "Start|Settings|Folder Options", and click on the View tab, then check the button labeled "Show all files."
2. Next, use Explorer to find MSDOS.SYS.
3. Right-click on its icon and uncheck the Read-only box to temporarily change its attributes for editing.
4. Finally, launch Notepad or another text editor and open the file. Be sure to reset the read-only attribute after you've finished.
If you don't have access to Windows, follow these steps to edit the "MSDOS.SYS" file under DOS:
1. Open an MS-DOS prompt and type "cd.." ( without quotation marks ), this brings you to the root.
2. "attrib -r -s -h msdos.sys" ( without quotation marks ): now you can modify "msdos.sys"
3. Make the changes needed, save the file and type " attrib +r +s +h msdos.sys" ( without quotation marks ).