MSDOS.SYS useful information
In Windows, MSDOS.SYS is a text file which may be used to control the boot process. It contains a [Paths] section that lists the locations for other Windows files (such as the Registry) and an [Options] section that you can use to control the boot process.
If you want to change any of the values in the MSDOS.SYS file, you can use any plain text editor (like Notepad).
IMPORTANT: Before you edit the MSDOS.SYS file, you should first make a backup copy of it. The original file is located in the root folder of your boot drive. If you delete the MSDOS.SYS file, your computer will not start. Also, make sure you can boot your computer with a floppy disk, and that the disk contains a plain text editor, such as Edit.com, that you can use to modify the MSDOS.SYS file, if anything goes wrong.
The [Options] section can contain the following settings:
- BootDelay=[Seconds] Default: 2
- Sets the amount of time the Starting Windows message remains on the screen before Windows continues to boot. If this setting is 0, then you will NOT be able to press the F8 key when Starting Windows appears to invoke the Startup menu.
BootSafe=[Boolean] Default: 0
- A setting of 1 forces your computer to boot in safe mode.
BootGUI=[Boolean] Default: 1
- A setting of 1 forces the loading of the Graphical User Interface (GUI). A setting of 0 disables the loading of the GUI.
BootKeys=[Boolean] Default: 1
- 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
- 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.
- Default: 1 if the system is running correctly, 3 if the system hung in the previous instance.
Use this setting to set the default menu item for Startup menu.
BootMenuDelay=[Number] Default: 30
- 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 will not function unless BootMenu=1 has been specified.
BootMulti=[Boolean] Default: 0
- 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
- A setting of 0 disables the safe mode boot warning message and the Startup menu.
BootWin=[Boolean] Default: 1
- 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.)
Logo=[Boolean] Default: 1
- A setting of 1 forces the default Windows logo to appear. A setting of 0 prevents the animated logo from being displayed.
Network=[Boolean] Default: 0
- A setting of 1 means the network was installed and adds Safe mode with network support as an option on the Windows Startup menu.
These settings prevent rebooting Windows in the "safe" or "command prompt only" modes. Specifically, they 1) disable the function keys during the boot process; 2) prevent the Startup menu from being displayed; 3) force Windows to boot into the normal mode, and 4) force Windows to load the Graphical User Interface.
Be prepared with a boot disk containing EDIT.COM and ATTRIB.EXE should you ever not be able to boot into Windows and need to get to the DOS or Safe Mode. You would need to boot with that disk, remove the read-only, hidden, and system attributes of
Note: Changes in the MSDOS.SYS file affect all users of the computer.
Note: The MSDOS.SYS file also contains a section with seemingly useless information. These entries are required for compatibility with programs that expect MSDOS.SYS to be at least 1024 bytes in length. For example, if an anti-virus scanner detects that MSDOS.SYS is smaller than 1024 bytes, it may assume that a virus has infected this file.
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