Windows 95/98/ME
Complete MSDOS.SYS Reference

Take Control of Your System at DOS Level!

... After all Windows 95/98/ME is a MIXED (read "partially enabled") 32-bit AND 16-bit [for backward compatibility with MS-DOS (DOS16 and DOS32) and older 16-bit Windows/WfWG 3.xx (Win16) programs] Graphical User Interface (GUI) protected mode virtual environment [... sorry, Operating System :)], which still depends on the good ol' MS-DOS 7.xx TSR modules (IO.SYS + COMMAND.COM), MS-DOS mode memory manager (HIMEM.SYS) and compatibility (legacy) drivers (IFSHLP.SYS) to load on top of the plain DOS command line based layer! The good news is Microsoft released Windows XP (eXPerience), a true 32-bit multitasking, multithreading and Symmetrical MultiProcessing (SMP) graphical OS, which does away once for all with the "ancient" 16-bit MS-DOS command line OS. But the bad news is WinXP does NOT support native/real/true/pure MS-DOS mode, necessary for old DOS based programs/games that require exclusive access to memory/video/audio/network hardware resources, and most of which are still memory "hungry", especially the ones that canNOT run from a DOS session/box/window inside Windows. Therefore, if using Windows 9x/ME, master your MSDOS.SYS parameters to BOOT into your System the way YOU want!

All MSDOS.SYS tips + guidelines shown here (and much, much more) are also available as part of Windows 9x/NT4/2000/ME/XP/2003 + DOS 7.xx/8.00 ©Tricks + Secrets Files [W95-11D.EXE], FREEware.
If you'd like to see how my MSDOS.SYS file looks like, and to view my DOS conventional + upper memory optimized CONFIG.SYS + AUTOEXEC.BAT startup files, head on to my MS-DOS 7.xx MEMory Specs Page.

NOTE: To learn about the "official" MSDOS.SYS parameters [the documented ones anyway :)], see the Contents of Windows MSDOS.SYS File MSKB article.
More info:

• Computer Hope.
• UKT Support.

A MUST: Microsoft REMOVED COMPLETELY the access to native/real/true/pure MS-DOS mode from Windows Millennium Edition (ME) [a.k.a. MS-DOS 8.00], but you CAN get it back by applying the Unofficial DOS Patch, which modifies COMMAND.COM + IO.SYS (from %windir%\COMMAND\EBD) + REGENV32.EXE (from %windir%\SYSTEM), in order to be able to boot to native MS-DOS and use DOS mode startup files (AUTOEXEC.BAT + CONFIG.SYS), Windows 95/98 style.
In case you're not comfortable modifying Windows system files, see this guide.

Contents:

• MSDOS.SYS Editing
• MSDOS.SYS Complete Reference Table
• Windows 95 - 98 Startup Menu + Bootup Keys

MSDOS.SYS is a Hidden, Read-only, System Windows 95/98/ME boot 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 FAT16 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/ME 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/ME OS NOR with Long File Names (LFNs)!

FYI: MSKB: How to Create an MSDOS.SYS File Larger Than 1024 Bytes.

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, System.
All these operations can be easily achieved using a plain DOS batch file, I called SYS95.BAT [part of W95-11D.EXE].

NOTE: Alternatively you can use one of these freeware MSDOS.SYS Editors to tweak ALL MSDOS.SYS parameters (including the UNDOCUMENTED ones) from a single, easy to use interface.

IMPORTANT: If a WINBOOT.INI file is also present in the root directory of the boot drive (usually C:\), MSDOS.SYS is automatically bypassed by the Win9x/ME bootup routine!
See "WINBOOT.INI", also in MYTIPS95.TXT [part of W95-11D.EXE], for complete details!
WINBOOT.INI MUST contain the SAME EXACT lines as MSDOS.SYS, so Windows can boot properly. In this case MSDOS.SYS can be moved/deleted altogether, but BEWARE of certain programs that may rely on its presence for proper operation.
Therefore if editing manually, you need to edit MSDOS.SYS first, make your desired changes, and only after that you need to copy it as WINBOOT.INI (overwriting the old one), to make sure BOTH their contents remain IDENTICAL.
SYS95.BAT routine detects the WINBOOT.INI presence, and performs all these necessary tasks automatically, to keep them in "sync" at all times. :)
WINBOOT.INI is NOT renamed by Win9x/ME if dual-booting to an older MS-DOS version, so it can be also edited from MS-DOS 6.xx, in which case it is copied as MSDOS.W40 (which is actually MSDOS.SYS renamed by the Win9x/ME dual-boot routine).
SYS95.BAT contains all necessary variables to edit MSDOS.W40 as well in MS-DOS 6.xx mode (using EDIT.COM), to avoid any possible headaches. :)

Some (still) prefer to dual-boot: keep the ol' MS-DOS version 6.xx (+ Windows/WfWG 3.1x) and have Win9x/ME installed in a separate directory. This way you have the choice to boot with your Win9x/ME 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 "DUAL BOOT" in MYTIPS95.TXT (part of W95-11D.EXE) for details] and choose to boot with your ol' MS-DOS version 6.xx, MSDOS.SYS is renamed to MSDOS.W40.
If also using MS-DOS 6.xx, make sure the DOS directory (default C:\MSDOS or 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 or in a directory in your path.

Below are listed SYS95.BAT command lines as shown in an EDIT.COM window:

If running SYS95 from native/real/true/pure MS-DOS, MSDOS.SYS will be edited in EDIT.COM, and if running SYS95 from a Windows DOS box/session, MSDOS.SYS will be edited in Notepad.exe. Both EDIT.COM and Notepad.exe are installed by the Win9x/ME Setup routine in a folder listed in the path statement (default install directories): EDIT.COM resides in C:\Windows\Command and Notepad.exe is found in C:\Windows. Therefore there is no need to specify their paths in SYS95.BAT. :)

Run SYS95.BAT from a PIF file (Windows MS-DOS Shortcut). To create a Win9x/ME 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 (example): "Edit MSDOS.SYS" (no quotes).
8. Click on Next.
9. Choose an icon. PIFMGR.DLL 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 (all Windows 9x/ME releases install 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.
You MUST 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), take a look at my MSDOS.SYS file (included ONLY as example). You might not see all these entries on your machine, depending on your Windows 95/98/ME 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 boot the way YOU want...

ALL MSDOS.SYS parameters, even those UNDOCUMENTED, what they do, and how to tweak them to MAXIMIZE your Windows 95/98/ME machine performance, are listed in this table.
MSDOS.SYS consists of 2 sections and supports all following entries:

LEGEND:

• [0] DEFAULT action is taken if a line does NOT appear under the [Options] section of MSDOS.SYS.
  NONDEFAULT action is opposite to DEFAULT if NOT stated otherwise.

• [1] LIMITATION: The Windows 95/98/ME main install directory/folder MUST abide by the old MS-DOS 8.3 (????????.???) Short File Names (SFNs) rules. Trying to use Long File Names (LFNs) will generate Operating System (OS) errors, because the Win9x/ME 32-bit GUI loads on top of the 16-bit MS-DOS 7.xx/8.00 layer at bootup time, which does NOT recognize LFNs!

• [2] If using a disk compression utility (such as MS DrvSpace), change the drive letter on the "HostWinBootDrv=" line to point to the host drive letter (usually H).

• [3] "UninstallDir=" points to the path you selected during Setup, ONLY IF you have chosen to backup your old OS at install time.

• [4] "AutoScan=" applies ONLY to Windows 95 B/C OSR 2.0 - 2.5, 98/98 SE and ME. Valid values:
  • 0 = NO scanning allowed.
  • 1 = Prompt user for scanning (scan begins if NO input for 60 seconds).
  • 2 = Allow automatic scanning (NO prompt).
  See "BYPASS AUTOSCAN", also in OSR2TIPS.TXT [part of W95-11D.EXE], for more details.

• [5] "BootConfig=" and "WinVer=" are specific ONLY to Windows 98, 98 SE and ME!
  "BootConfig=MYCONFIG" (example if using multiple boot configurations) is UNDOCUMENTED and allows alternative boot setup. To make this work properly CONFIG.SYS MUST also include this same EXACT string as a MENUITEM= under its [MENU] section: MYCONFIG and also as a section by itself: [MYCONFIG] . "BootGUI=" MUST also be set to 1 in MSDOS.SYS.
  Selecting MYCONFIG from the Startup Menu will force Windows 98/ME to boot with this particular option. Selecting any other option will default to native/real/true/pure MS-DOS mode.
  [Thank you Bill!]
  See my CONFIG.SYS [part of W95-11D.EXE] for multi-boot MENU examples.

• [6] Delay allows time to press a Startup Menu function key or key combo (some are UNDOCUMENTED): F4, F5, F6, F8, Ctrl, Shift, Ctrl+F5, Ctrl+F8, Shift+F5 or Shift+F8 (the Ctrl key can be used ONLY with Windows 98/ME). DEFAULT is 0 if "BootKeys=0".
  "BootDelay=" is NOT supported in Windows 98/ME (automatically defaults to 0)!

• [7] If "BootKeys=0", then "BootMenu=1" and "BootMulti=0" do NOT change the DEFAULT action.
  WARNING: Do NOT boot into your old/previous OS (MS-DOS 6.00 - 6.22) if using Windows 95 B/C OSR 2.x or Windows 98/98 SE(U)! You won't be able to get back into OSR2/Win98 UNLESS YOU APPLY THE "DUAL-BOOT IN OSR2/WIN98" FIX FIRST, also in OSR2TIPS.TXT [part of W95-11D.EXE]!
  See also "DUAL BOOT", also in MYTIPS95.TXT, [part of W95-11D.EXE], for more info.

• [8] Startup Menu option 3 ("Safe mode") is highlighted if a previous Windows 95/98 load failed.

• [9] "BootMulti=" and "BootWin=" are available ONLY IF using the dual-boot feature built into Windows 9x/ME OS, AND still using a previously installed version of MS-DOS (6.00 - 6.22).

• [10] "DisableLog=" and "SystemReg=" are UNDOCUMENTED!

• [11] See "DOUBLE BUFFER", also in MYTIPS95.TXT [part of W95-11D.EXE], for more info.

• [12] "LoadTop=1" (default) may generate incompatibilities with some older DOS programs/TSRs which need to find COMMAND.COM into the Conventional Memory Area (CMA) at the bottom of the 640K barrier (a.k.a. "low" memory). In such cases change this setting to "LoadTop=0" to prevent COMMAND.COM/DRVSPACE.BIN from loading into the High Memory Area (HMA), which is located at the top of the CMA, just below the 640K barrier.

• [13] "Logo=0" may solve 3rd party memory management conflicts if using Symantec (QuarterDeck) QEMM386, McAfee (Helix) NetRoom RM386, Qualitas (IBM) 386MAX, Uwe Sieber UMBPCI (+ HIRAM) etc memory managers in CONFIG.SYS.
  See "95/98/ME SETUP + MEMORY MANAGERS" (also in MYTIPS95.TXT) and MEMORY.TXT [both part of W95-11D.EXE] for details and guidelines on using 3rd party memory managers with your Windows 9x/ME OS.

• [14] "Network=1" MUST be present for "Safe Mode with Network support" to appear as option 4 on the Startup Menu.

FYI: Microsoft REMOVED the display of the Startup Menu from Windows ME, but you can still access most of these options by hitting the "combo" keys (listed below) at bootup!

And if you were wondering how the Windows 95/98 Startup Menu looks like, here is a screen shot of the bootup display, shown (every time you boot) ONLY IF you enable the "BootMenu=1" entry under the [Options] section of your MSDOS.SYS, or (this one time ONLY) if you press F8 at the beginning of the boot sequence, right after your computer's BIOS POST (Power On Self Test) screen:

    Microsoft Windows 95 (98) Startup Menu        


1. Normal 
 [1]
  
2. Logged (\BOOTLOG.TXT)
3. Safe mode
4. Safe mode with network
support [2]
5. Step-by-step confirmation
6. Command prompt only [3]
7. Safe mode command prompt only
8. Previous version of MS-DOS [4]

     Enter a choice: 10 [5]


  F5=Safe mode Shift+F5=Command prompt
  Shift+F8=Step-by-step confirmation[N]

LEGEND:

• [1] Default startup item (Normal Windows 9x/ME GUI bootup) is highlighted.

• [2] This option appears on Networked and/or TCP/IP enabled systems, ONLY IF the line "Network=1" exists under the [Options] section of MSDOS.SYS.

• [3] This option boots to the native/real/true/pure MS-DOS mode prompt without loading the "WIN" module into memory (Windows 9x/ME does NOT process the Registry and the GUI does NOT load).

• [4] This option boots into the previous MS-DOS release (from 6.00 up to 6.22) or other 3rd party DOS OS, and enables the use of Windows/WfWG 3.1x (ONLY IF you kept them!).
  WARNING: Do NOT boot into your old/previous OS (MS-DOS 6.xx) if you are using Windows 95 B/C OSR 2.x or Windows 98! You won't be able to get back into OSR2/Win98 again, UNLESS YOU APPLY THE "DUAL-BOOT IN OSR2/WIN98" FIX FIRST!

• [5] Delay in seconds before default startup selection initiates the bootup sequence, to enable the function keys displayed at the bottom of the screen: F5, Shift+F5 and Shift+F8, and the other (HIDDEN!) Win9x/ME bootup keys (ONLY if the "BootKeys=1" entry is present under the [Options] section of MSDOS.SYS): F4, F6, F8, Ctrl, Shift and Ctrl+F5. These keys let the user take control and change the default bootup choice at will. This can also be achieved by selecting a number (1 to 8), by hitting the corresponding numeric key, or by using the Up or Down Arrow keys, and then pressing Enter.

Windows 95 (98) Startup Menu key "combos" and what they do [also available in Windows ME]:

• F4 = Previous version of MS-DOS (from 6.00 up to 6.22, or another 3rd party DOS OS, if any).

• F5 = Safe mode without Network/TCP/IP support, bypassing CONFIG.SYS and AUTOEXEC.BAT entirely (if any).

• F6 = Safe mode with Network/TCP/IP support (ONLY IF "Network=1" present under the MSDOS.SYS [Options] section), bypassing CONFIG.SYS entirely (if any).

• F8 = Safe mode (Win95/OSR1/OSR2 ONLY) or Logged mode (Win98/ME ONLY). BOOTLOG.TXT is created in the root directory of the boot drive/partition (usually C:\) in Logged mode.

• Shift (or Ctrl) + F5 = Safe mode command prompt only (native/real/true/pure MS-DOS mode with NO devices/drivers/TSRs loaded in memory). CONFIG.SYS and AUTOEXEC.BAT are bypassed (if any).

• Shift + F8 = Step-by-step confirmation of ALL CONFIG.SYS and AUTOEXEC.BAT lines (if any). This changes the [N] box to [Y], visible ONLY IF the Startup Menu is displayed, and needs to be followed by pressing the Enter key. Then you can enable (default) or disable each individual line, by pressing Y (for "Yes") or N (for "No").

• Alt, Esc = Hold down (Alt) or press (Esc) while booting to force the Windows bootup logo to disappear (ONLY IF "Logo=1" present under the MSDOS.SYS [Options] section) and display underlying bootup messages (if any) generated by loading memory manager(s) and/or devices/drivers/TSRs.
  [Thank you HKMonkey!]

Hidden features, oddities + BUGs I discovered:

ONLY IF "BootGUI=0" under the MSDOS.SYS [Options] section, you will notice these changes at bootup:

• F8, Ctrl = Displays the Startup Menu ONLY IF "BootMenu=0" under the MSDOS.SYS [Options] section.

• F5, F6, Shift = COMMAND.COM, DBLBUFF.SYS, HIMEM.SYS and IFSHLP.SYS load from IO.SYS, bypassing their CONFIG.SYS lines (if any). If COMMAND.COM NOT found in %winbootdir% (specified on the "WinBootDir=" MSDOS.SYS line under the [Paths] section, usually C:\WINDOWS) or in the root directory of the boot drive (usually C:\), or/and HIMEM.SYS and/or IFSHLP.SYS NOT found in %winbootdir%, the bootup routine defaults to "Safe mode command prompt only" (native/real/true/pure MS-DOS mode with NO devices/drivers/TSRs loaded in memory).

• Shift (or Ctrl) + F5 = Command prompt only (native/real/true/pure MS-DOS mode). CONFIG.SYS and AUTOEXEC.BAT are processed (if any).

• Windows 9x/ME automatically loads the interface (GUI) ONLY IF a "SHELL=" line is NOT present in CONFIG.SYS (example):

  SHELL=C:\COMMAND.COM C:\ /E:1024 /P /F

• The size of the COMMAND.COM module loaded in memory is about 2 KB smaller than if "BootGUI=1", no matter if a "SHELL=" line is present or not in CONFIG.SYS.

NOTES:

• The Ctrl key can be used ONLY in Windows 98/ME, NOT in Windows 95/OSR1/OSR2.
• If WINBOOT.INI is present in the root directory of the boot drive/partition (C:\ by default) MSDOS.SYS is automatically bypassed. See "WINBOOT.INI", also in MYTIPS95.TXT [part of W95-11D.EXE], for details.