Information about the MSDOS.SYS file
The [Paths] section can contain the following settings:
HostWinBootDrv={Root of Boot Drive}
Default: C
Purpose: Specifies the location for the root of the boot
drive.
WinBootDir={Windows Directory}
Default: Directory specified during Setup (for
example, C:\WINDOWS)
Purpose: Lists the location of the necessary files for
booting.
WinDir={Windows Directory}
Default: Directory specified during Setup (for
examples C:\WINDOWS)
Purpose: Lists the location of the Windows directory
specified during Setup.
The [Options] section can contain the following settings:
BootDelay={Seconds}
Default: 2
Purpose: Sets the amount of time the "Starting Windows"
message remains on the screen before Windows continues to boot.
BootFailSafe={Boolean}
Default: 0
Purpose: A setting of 1 forces your computer to boot in safe
mode.
BootGUI={Boolean}
Default: 1
Purpose: A setting of 1 forces the loading of the GUI
interface. A setting of 0 disables the loading of the GUI interface.
BootKeys={Boolean}
Default: 1
Purpose: A setting of 1 enables the use of the function key
boot options (that is, F4, F5, F6, and F8).
A setting of 0 disables the use of these function keys during the
boot process
NOTE: A setting of BootKeys=0 overrides the use of BootDelay=n.
BootMenu={Boolean}
Default: 0
Purpose: A setting of 1 enables the startup menu. If this
setting is 0, then you must press the F8 key when "Starting Windows"
appears to invoke the startup menu.
BootMenuDefault={Number}
Default: 1 if the system is running correctly, 4 if the
system hung in the previous instance
Purpose: Use this setting to set the default menu item for
startup.
BootMenuDelay={Number}
Default: 30
Purpose: This setting is used to set the number of seconds
your system will pause on the startup menu. If the number of seconds
counts down to 0 without intervention, the BootMenuDefault is
activated.
BootMulti={Boolean}
Default: 0
Purpose: A setting of 0 disables the multi-boot option. (For
example, with a setting of 0 you cannot boot your previous operating
system.) A setting of 1 enables the F4 and F8 keys to boot
your previous operating system.
NOTE: This setting is set to 0 by default to avoid the corruption of
data by allowing you to inadvertently boot MS-DOS and run a disk
utility that does not recognize long filenames.
BootWarn={Boolean}
Default: 1
Purpose: A setting of 0 disables the safe mode boot warning
message and the startup menu.
BootWin={Boolean}
Default: 1
Purpose: A setting of 1 forces Windows to load at startup. A
setting of 0 disables Windows as your default operating system (this
is useful only if you have MS-DOS version 5.x or 6.x on the computer).
NOTE: Pressing F4 inverts the default only if BootMulti=1. (For
example, pressing the F4 key with a setting of 0 forces Windows to
load.)
DoubleBuffer={Boolean}
Default: 0
Purpose: A setting of 1 is a conditional setting that enables
double-buffering for controllers that need it (for
example, SCSI controllers). A setting of 2 is an
unconditional setting that enables double-buffering regardless of
whether the controller needs it or not.
DBLSpace={Boolean}
Default: 1
Purpose: A setting of 1 allows the automatic loading of the
DBLSPACE.BIN file. A setting of 0 prevents the automatic loading of
this file.
DRVSpace={Boolean}
Default: 1
Purpose: A setting of 1 allows the automatic loading of the
DRVSPACE.BIN file. A setting of 0 prevents the automatic loading of
this file.
LoadTop={Boolean}
Default: 1
Purpose: A setting of 0 does not let Windows load COMMAND.COM
or DRVSPACE.BIN/DBLSPACE.BIN at the top of 640K. If you are having
compatibility problems with software that makes assumptions about
the available memory try setting this to 0.
Logo={Boolean}
Default: 1
Purpose: A setting of 1 forces the default Windows logo to
appear. A setting of 0 prevents the animated logo from being
displayed. A setting of 0 also avoids hooking a variety of
interrupts that can create incompatibilities with certain
third-party memory managers.
Network={Boolean}
Default: 0
Purpose: A setting of 1 means the network was installed and
adds "Start Windows, bypassing startup files, with network support"
as an option on the Windows startup menu.
Undocumented Entries (not by Microsoft, anyway):
The [Options] section can contain the following settings:
DisableLog={Boolean}
Default: 0
Purpose: disables creation of bootlog.txt during startup.
The Msdos.sys file also contains a section that contains seemingly useless information. This information is necessary to support programs that expect the Msdos.sys file to be at least 1024 bytes in length. For example, if an anti-virus program detects that the Msdos.sys file is less than 1024 bytes, it may assume that the Msdos.sys file is infected with a virus. If you delete the Msdos.sys file your computer will not start.
The following statement, followed by a series of "X"s, appears in the Msdos.sys file:
;The following lines are required for compatibility with other programs. ;Do not remove them (Msdos.sys needs to be }1024 bytes).
Since each line begins with a semicolon (;), the lines are not read by the system.
How to Edit the Msdos.sys File
If you want to change any of the values in the Msdos.sys file, follow these steps to edit the file:
- Click Start
- Click on Find
- Click on Files or Folders
- Type "msdos.sys" in the Named box (without the quotation marks).
- In the Look in box, select Drive C.
- Click on Find Now
- Right click on the Msdos.sys file
- Click on Properties
- Remove the check on the Read-Only box
- Remove the check on the Hidden box
-
Click on OK
- Right click the Msdos.sys file
- Click on Open
- Choose Wordpad when it asks you "Choose the program you want to use"
-
Click on OK
- Make the changes you want to make
- Click on File
- Click on Save
- Exit Wordpad
- Right click on the Msdos.sys file
- Click on Properties
- Place a check on the Read-Only box
- Place a check on the Hidden box
-
Click on OK
- Reboot the computer
Thanks to Annoyances.org for this information.