Help with the boot.ini:

The "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 disk 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 easily select which operating system to load. In addition this file is also used to point to the locations of each of the operating systems.�

Basic example of the boot.ini file:

[boot loader]
 timeout=5
 default=multi(0)disk(0)rdisk(1)partition(1)\WINDOWS
 [operating systems]
 multi(0)disk(0)rdisk(1)partitions(1)\WINDOWS="Microsoft Windows XP Home Edition" /fastdetect

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 adapters 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 disk 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 the boot.ini may have "scsi(x)" instead of "multi(x).

disk(x)
The disk on the controller. If "multi(x)" is used 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.

paritions(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.�

Example of the boot menu:

If multiple operating systems are setup in the boot.ini, as the computer is booting you will see a menu similar to the below example. This allows the user to select between multiple operating systems. If your computer does not have multiple operating systems, however 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.�

How to modify the boot.ini:

The boot.ini file is a hidden system file located in the root directory of your primary hard disk drive. To edit this file we recommend you follow the below steps. 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 a MS-DOS prompt to edit the boot.ini file boot into the recovery console to edit the file.
2. At the MS-DOS prompt type:

c: 
 cd\ 
 attrib -r -a -s -h boot.ini 
 edit boot.ini  

Available boot.ini switches:

Below is a listing of available boot.ini switches and a brief explanation. These switches can 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 of the computer booting named ntbtlog.txt.

/burnmemory
Cuases the operating system to ignore about the memory specified after the switch. For example "/burnmemory=64" instructs the operating system to ignore 64MB 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 32MB.

/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 computers 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. This mode can be easily accessed without modifying any files by pressing the "F8" key as the computer is booting. See CHSAFE for additional information on how to enter safe mode.

/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 the Windows boot.ini

Users who have a corrupt or missing boot.ini file, are running Microsoft Windows XP, and have a Microsoft Windows XP CD can rebuild the systems boot.ini file by following the below steps.

1. Insert the Microsoft Windows XP CD into the computer. Note: If you have a system recovery CD or restore CD these steps will likely not work for your computer.

2. Reboot the computer with the CD and press any key when prompted to press any key to boot from the CD.

3. Once in the Microsoft Setup menu press R to open the recovery console.

4. Select the operating system you wish to use; if you only have Windows XP on the computer you will only have one prompt.

5. Once prompted for the password enter the Admin password and press enter.

6. Once at the command prompt type bootcfg /rebuild to start the rebuild process.

7. The rebuild process will step you through a number of steps depending upon how many operating systems you have on the computer and how the computer is setup. Below is a listing of the common steps you are likely going to encounter.

* Prompt for the identified versions of Windows installed. When you receive this prompt press Y if the bootcfg command properly identified each of the Windows operating systems installed on the computer. It is important to realize this command will only detect Windows XP, Windows 2000, and Windows NT installations.

* Prompt to enter the load identifier. This is the name of the operating system for the boot.ini. For example Microsoft Windows XP Home users would enter "Microsoft Windows XP Home edition".

* Prompt to Enter OS load options. When this prompt is received type /fastdetect to automatically detect the available options. 8. Once you have completed all the available options in the rebuild and are back at the prompt type exit to reboot the computer.

This page last updated March 21, 2005