Purpose of the BOOT.INI File

 Last reviewed: September 12, 1997
Article ID: Q99743
The information in this article applies to:
  • Microsoft Windows NT operating system version 3.1
  • Microsoft Windows NT Advanced Server version 3.1
  • Microsoft Windows NT Workstation version 3.5, 3.51, and 4.0
  • Microsoft Windows NT Server version 3.5, 3.51, and 4.0

The Boot.ini file is used by Windows NT (specifically, Ntldr) to determine the operating system options to display during the startup (boot) process. Boot.ini is flagged as a read-only, system file by default and should not require any manual modification. You can change its contents easily from Control Panel by choosing the System icon.

The following is a typical Boot.ini file: 

   [boot loader]
   timeout=30
   default=scsi(0)disk(0)rdisk(0)partition(1)\winnt

   [operating systems]
   scsi(0)disk(0)rdisk(0)partition(1)\winnt = "Windows NT" /NODEBUG
   C:\ = "Previous Operating System on C:\"
The following are line-by-line explanations of the above Boot.ini file: 

   [boot loader]
   timeout = 30
Timeout specifies the amount of time Windows NT waits before choosing the default operating system. 

   default=scsi(0)disk(0)rdisk(0)partition(1)\winnt
Default specifies the default operating system. Note: Whenever the operating system is Windows NT, the new storage path syntax is used. For more information on this syntax, query on the following words in the Microsoft Knowledge Base: 

   NT and GEOMETRY

   [operating systems]
   scsi(0)disk(0)rdisk(0)partition(1)\winnt = "Windows NT" /NODEBUG
   C:\ = "Previous Operating System on C:\"

   scsi(0) means that the primary controller (usually the only one) is
   responsible for the device. If there were two SCSI cards and the disk
   was hanging off the second one, it would be called scsi(1).

   disk(0) refers to physical disk 1.

   rdisk(0) - The rdisk() parameter refers to which SCSI logical unit
   (LUN) to use, which could be a separate disk, but the vast majority of
   SCSI setups have only one LUN per SCSI ID.

   partition(1) in this example is the only partition on the first drive
   in the computer. If there were two partitions, C and D, C would be
   partition(1) and D would be partition(2).

   \winnt is the directory that multi-boot will look at to boot from one
   of the specified SCSI card's disk and partition.

   /NODEBUG specifies that there's no debugging information being
   monitored. Debugging information is only useful for developers and
   does slow down Windows NT somewhat.
The /SOS switch can be added to display driver names while they are being loaded during the Windows NT boot. By default, the OS Loader screen only echos progress dots. 

   The Previous Operating System on C:\ implies that it is MS-DOS,
   because "C:\" is an MS-DOS path.

Additional query words: prodnt
Keywords : ntboot kbother

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Last reviewed: September 12, 1997
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