Information and help with the file boot.ini

Updated: 04/26/2017 by Computer Hope

boot.iniThe file boot.ini is a Microsoft initialization file found on the Microsoft Windows NT,  Microsoft Windows 2000, and Microsoft Windows XP operating systems. This file is always located on the root directory of the primary hard drive. In other words, it is located at C:\ directory or the C Drive. This file is used by Microsoft Windows as a method of displaying a menu of operating systems currently on the computer and allowing the user to select what operating system to load. The information in boot.ini is also used to point to the locations of each of the operating systems.

How to view the contents of boot.ini

The file boot.ini can be viewed and some options can be changed by following the steps below.

  1. Click Start, Run
  2. In the run line type: msconfig and press enter.
  3. Click the boot.ini tab.

Tip: If you have an option in the boot menu that doesn't work, such as a missing version of Windows. Try clicking the "Check All Boot Paths" button in the boot.ini tab to fix this issue without having to manually edit boot.ini as instructed below.

If multiple operating systems are configured in boot.ini, as the computer boots a menu similar to the example below is shown. If your computer does not have multiple operating systems, but this menu still appears each time your computer boots, it is likely that your boot.ini is improperly configured.

Please select the operating system to start:

Microsoft Windows XP Home Edition
Microsoft Windows 2000

Use the up and down arrow keys to move the highlight to your choice.
Press Enter to choose.

For troubleshooting and advanced startup options for Windows, press F8.

Basic example of a boot.ini file

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(1)partition(1)\WINDOWS="Microsoft Windows XP Home Edition" /fastdetect

In the above example, boot.ini contains two sections, the [boot loader], and [operating systems]. Within the boot loader section there are two lines. The "timeout" value defines how long, in seconds, the boot menu should be shown. We recommend that the timeout be set to at least five seconds. The "default" line is the default operating system that boot.ini will load. If multiple operating systems are configured in the boot.ini, the default operating system is automatically selected and used if not changed by the user by the time the timeout value expires.

The next section, or the "operating system" section, is used to list and specify the location of each of the operating systems installed on the computer. Below is a listing of each of the options.

Option Description
multi(x) This option is used with IDE and ESDI drives and is also used with SCSI drives for computers using Windows NT. The number used in the above example is "0", this number is the adapter's number and should always be "0" for computers that rely on the BIOS to load system files.
  • In a computer using only IDE this option will work with up to four hard drives.
  • In a computer using only SCSI this option will work with the first two drives on the primary SCSI controller.
  • Finally, if a computer is using IDE and SCSI this option will work with the IDE drives on the first controller.
scsi(x) If the computer has a SCSI controller and is not using BIOS to load the system files, boot.ini's configuration may list "scsi(x)" instead of "multi(x).
disk(x) The disk on the controller. If multi(x) is used, this value will always be 0. However, if scsi(x) is defined, this value will be SCSI address.
rdisk(x) Which disk on the controller is being used. In the above example, we are using an rdisk of "1", which indicates the second disk on the primary controller is being used. This value may be between "0" and "3" and is always set to "0" when "scsi(x)" is being used.
partition(x) Which partition the operating system is on. In the above example, the operating system is on the first partition of the drive.
\WINDOWS="..." Finally, the last portion of this line defines the directory of where Windows is located and what the boot menu should display as the operating system. In the above example, the boot menu would display "Microsoft Windows XP Home Edition" as a selection.

How to modify boot.ini

The file boot.ini file is a hidden system file located in the root directory of your primary hard drive. To edit this file we recommend you follow the steps below.

  1. From Windows, open an MS-DOS prompt by clicking "Start" and then "Run" and typing "cmd" in the text box. If you are not able to get into an MS-DOS prompt to edit boot.ini, boot into the recovery console to edit the file.
  2. At the MS-DOS prompt, type:

c: <press enter>
cd\ <press enter>
attrib -r -a -s -h boot.ini <press enter>
edit boot.ini <press enter>

Available boot.ini switches

Below is a listing of available boot.ini switches and a brief explanation. These switches can be used to help setup or troubleshoot a computer.

Switch Description
/basevideo Causes the operating system to use a standard VGA display when booting into the operating system.
/bootlog Creates a log file named ntbtlog.txt of the computer booting.
/burnmemory Causes the operating system to ignore the memory specified after the switch. For example, "/burnmemory=64" instructs the operating system to ignore 64 MB of physical memory.
/debug Causes the kernel debugging to be enabled.
/fastdetect Causes NTDETECT to not detect serial and parallel devices and instead let Plug-and-Play handle detection.
/maxmem Limit the operating system to use the maximum memory of what the user specifies. For example, "/maxmem=32" instructs the operating system to use a maximum of 32 MB.
/noguiboot Microsoft Windows 2000 and above switch that, if enabled, will not load the graphics driver to display the graphic as Windows is starting
/nopae Microsoft Windows 2000 switch that disables the computer's ability to utilize Intel Physical Address Extensions.
/numproc Instructs the operating system on how many processors it is capable of using.
/onecpu Causes the operating system to utilize one of the processors in a multi-processor computer.
/pae Microsoft Windows 2000 switch that enables the computer to utilize Intel Physical Address Extensions.
/pcilock Prevents the operating system from automatically assigning IO/IRQ resources to PCI devices.
/safeboot Boot the computer safely (Safe Mode). This mode can also be accessed without modifying any files by pressing the "F8" key as the computer is booting.
/sos Causes the operating system to print out information as it being processed.
/w95 Used when booting Windows 95 or Windows 98.
/w95dos Used when booting MS-DOS.
/year Option used to cause the operating system to ignore the year provided by systems the real-time clock and instead utilize the year specified after the switch. For example, a user may type /year=2003.

How to rebuild boot.ini

Additional information

  • See our boot definition for further information and related links on this term.