Msdos.sys Boot Path and Options

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Article ID: Q118579
Revision Date: 07-MAR-1997

The Windows 95 Setup program creates a file called Msdos.sys in the root folder and sets the file's Read-Only, System, and Hidden attributes. Unlike the Msdos.sys file in MS-DOS, this file is a text file. It contains a [Paths] section that lists the locations for other Windows 95 files (such as the registry) and an [Options] section that you can use to personalize the boot process.

MORE INFORMATION

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 example, C:\WINDOWS)
Purpose: Lists the location of the Windows 95 directory specified during Setup.

The [Options] section can contain the following settings and must be manually inserted:

AutoScan=<Number>
Default: 1
Purpose: Defines whether or not ScanDisk is run after a bad shutdown.
A setting of 0 does not run ScanDisk; 1 prompts before running ScanDisk; 2 does not
prompt before running ScanDisk but prompts you before fixing errors if any errors are
found.

This setting is used only by OEM Service Release 2.

BootDelay=<Seconds>
Default: 2
Purpose: Sets the amount of time the "Starting Windows" message remains on the
screen before Windows 95 continues to boot.

BootSafe=<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 95" appears to invoke the Startup menu.

BootMenuDefault=<Number>
Default: 1 if the system is running correctly 3 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.

NOTE: This option is not functional unless BootMenu=1 has been added to the [Options]
section of the Msdos.sys file.

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 prevent you from inadvertently starting
MS-DOS and damaging data by running a disk utility that does not recognize long file names.

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 95 to load at startup. A setting of 0 disables
Windows 95 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 95 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.

NOTE: Windows 95 uses either Dblspace.bin or Drvspace.bin if either is present in the
root folder of the boot drive at startup. To disable a compression driver from being loaded at startup, use both settings in the Msdos.sys file. For example:

DBLSpace=0
DRVSpace=0

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.

NOTE: Windows 95 uses either Dblspace.bin or Drvspace.bin if either is present in the
root folder of the boot drive at startup. To disable a compression driver from being loaded at startup, use both settings in the Msdos.sys file. For example:

DBLSpace=0
DRVSpace=0

LoadTop=<Boolean>
Default: 1
Purpose: A setting of 0 does not let Windows 95 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 95 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 "Safe mode with
network support" as an option on the Windows 95 Startup menu.

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:

1.Click the Start button, point to Find, then click Files Or Folders.

2.In the Named box, type "msdos.sys" (without quotation marks). In the
Look In box, click your boot drive (usually drive C, or drive H if drive C is compressed).
Click the Find Now button.

3.Use the right mouse button to click the Msdos.sys file and then click Properties on the menu that appears.

4.Click the Read-Only and Hidden check boxes to remove these attributes from the
Msdos.sys file and then click OK.

5.Use the right mouse button to click the Msdos.sys file and then click Open With on
the menu that appears.

6.In the "Choose the program you want to use" box, click WordPad and then click OK.

7.Make the changes you want to the Msdos.sys file. When you are done, save the file
and then quit WordPad.

8.Use the right mouse button to click the Msdos.sys file and then click Properties on the menu that appears.

9.Click the Read-Only and Hidden check boxes to set these attributes for the file and
then click OK. Close the Find window.