MSDOS.SYS is a System, Read-only, Hidden Windows 95/98 file, located in the root folder (directory) of your boot drive (default is C:\), and if using DrvSpace (Microsoft "disk-doubler" utility) to compress your hard drives/partitions, there is another MSDOS.SYS file located in the root folder of your compressed volume (default is H:\). BOTH these files need to be IDENTICAL to have your Windows 9x computer boot properly with DrvSpace installed!

CAUTION: If dual-booting with MS-DOS 6.xx, make sure to NOT use DblSpace, the older Microsoft disk compression tool (bundled with MS-DOS 6.00 - 6.20), which is NOT compatible with Windows 9x OS or with the Long File Names (LFNs)!

You can edit/view/print MSDOS.SYS using Notepad.exe in Windows (Windows default ASCII/text editor), or EDIT.COM in DOS (MS-DOS default ASCII/text editor).
Before editing, you MUST strip MSDOS.SYS of its default attributes (Hidden, Read-Only and System), to be able to modify it.
After making your desired modifications to MSDOS.SYS, save it, exit the text editor, and then reboot your machine so the changes can take effect.
Optional: restore MSDOS.SYS attributes back to the original (Hidden, Read-Only and System), to make it compatible once again with Windows 95/98 OS bootup routine.
All these operations can be easily achieved using a plain DOS batch file, I called SYS95.BAT,

Some (still) prefer to dual-boot: keep the ol' MS-DOS version 6.xx (+ MS Windows/WfWG 3.1x) and have Win95/98 installed in a separate directory. This way you have the choice to boot with your new Win95/98 configuration, or with your old version of MS-DOS, and eventually use Windows/WfWG 3.1x (if you kept it) like I did. :)
If you dual-boot (read the "DUAL BOOT" topic in MYTIPS95.TXT, and choose to boot with your ol' MS-DOS version 6.xx, MSDOS.SYS is renamed to MSDOS.W40. SYS95.BAT contains the necessary variables to edit MSDOS.W40 as well in MS-DOS 6.xx mode.
If also using MS-DOS 6.xx, make sure the DOS directory (default C:\DOS) is mentioned in your path (on the PATH line in your Autoexec.bat or Config.sys), and that EDIT.COM resides in your DOS directory.

Below are SYS95.BAT command lines, as shown in EDIT.COM (using here EDIT.COM to view/edit/print MSDOS.SYS). EDIT.COM is installed by Win95/98's Setup routine in your C:\Windows\Command subfolder (added to your default PATH statement, so no need to mention EDIT.COM's path in SYS95.BAT):

And here I used Notepad in SYS95.BAT, to edit/view/print MSDOS.SYS. Notepad resides in your Windows folder by default (therefore you don't need to specify Notepad's path in SYS95.BAT):

Run SYS95.BAT from a PIF file (Windows MS-DOS Shortcut). To create a Win95/98 Desktop Shortcut:

1. Right-click on your Desktop.
2. Select New.
3. Select Shortcut.
4. Browse for SYS95.BAT to the folder where it resides.
5. Double-click on SYS95.BAT.
6. Click on Next.
7. Select a name for your Shortcut.
8. Click on Next.
9. Choose an icon. PIFMGR.DLL's icons are displayed by default for all MS-DOS shortcuts, but you can change its icon later, after the shortcut is created on your Desktop (see next paragraph).
10. Click Finish.

To change your MS-DOS Shortcut icon:

1. Right-click on your MS-DOS Shortcut.
2. Select Properties.
3. Click the Program tab.
4. Click Change Icon.
5. Browse through your local drives/folders for your favorite .DLL, .ICO, .ICL or .EXE files containing Windows icons.
6. Select an icon.
7. Click OK when you're done.
8. Click OK/Apply again to exit and save changes.

Now you'll see a new shortcut on your Desktop (called SYS95.BAT if you kept its original name):

1. Right-click on it.
2. Select Properties.
3. Click on the Program tab.
4. Check the "Close on exit" box.
5. Click the Misc tab.
6. Uncheck the "Warn if still active" box.
7. Click OK/Apply to save changes.

That's it.

From now on, you'll be able to view/edit MSDOS.SYS contents using your favorite text editor (Windows 95/98 comes with both MS-DOS EDIT.COM and Windows Notepad). Change/add MSDOS.SYS entries to customize your system, then save your changes and close the editor when you're done.
Now you'll have to reboot your machine for the new settings to take effect, ONLY IF you have modified MSDOS.SYS.
No matter which text editor you are using (Notepad is shown below), MSDOS.SYS looks something like this (you might not see all these entries on your machine, depending on your Windows 95/98 startup configuration):

[Paths]
WinDir=C:\WINDOWS
WinBootDir=C:\WINDOWS
HostWinBootDrv=C

[Options]
Autoscan=0
BootGUI=0
BootKeys=1
BootMenu=1
BootMenuDefault=1
BootMenuDelay=5
BootMulti=1
BootWin=1
DblSpace=0
DisableLog=1
DoubleBuffer=0
DrvSpace=0
LoadTop=0
Logo=1
Network=1
SystemReg=0
WinVer=4.10.2222

;The following lines are required for compatibility with other programs.
;Do not remove them (MSDOS.SYS needs to be >1024 bytes).
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxa
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxb
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxc
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxd
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxe
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxf
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxg
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxh
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxi
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxj
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxk
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxl
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxm
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxn
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxo
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxp
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxq
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxr
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxs

Now you're ready to add/modify the MSDOS.SYS entries to have Windows 95/98 boot the way YOU want...