Boot.ini is a hidden and read-only text file on the root of the system partition of that is used to create the boot loader menu.
What is boot.ini?
A hidden, read-only text file on the root of the system partition of Microsoft Windows NT, Windows 2000, Windows XP and Windows Server 2003 that is used to create the boot loader menu. For example, a typical boot.ini file for a default Windows NT installation might look like this:
[boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect C:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdcons
A close correspondence can be seen between the appearance of the boot.ini file and the boot loader menu, which the ntldr program creates during the Windows NT boot sequence.
You can safely modify some of the settings in this file using the System utility in Control Panel. If you need to edit the file directly, use the attrib command to first remove its read-only, system, and hidden attributes and then modify the file using a text editor such as Microsoft Notepad. Do this carefully, as an error in the boot.ini file can prevent the system from booting.
Boot Options in Windows
Windows Vista and recent Microsoft Operating Systems don’t use the Boot.ini file to configure boot options. The Windows boot loader architecture includes a firmware-independent boot configuration and storage system called Boot Configuration Data (BCD) and a boot option editing tool, BCDEdit (BCDEdit.exe).
Editing Boot Options
To edit boot options in Windows, use BCDEdit (BCDEdit.exe), a tool included in Windows. To use BCDEdit, you must be a member of the Administrators group on the computer. You can also use the System Configuration utility (MSConfig.exe) to change boot settings.
To change boot options programmatically in Windows, use the Windows Management Instrument (WMI) interface to boot options. This BCD WMI interface is the best method to programmatically change the boot options.