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Setup and Startup

Windows 2000 uses the Advanced Reduced Instruction Set Computing (RISC) naming convention to define the path to a Windows 2000 installation.

Using ARC Pathnames

The Advanced RISC Computing (ARC) pathnames in Boot.ini point to the location of the boot partition for all Windows 2000 installations. A single line in Boot.ini represents each installation. During the startup process, the boot loader screen prompts you to choose an installation.

The ARC names in the file Boot.ini are similar to the following:

  • Multi(W)disk(X)rdisk(Y)partition(Z)\%systemroot%

  • Scsi(W)disk(X)rdisk(Y)partition(Z)\%systemroot%

  • Signature(8b467c12)disk(1)rdisk(0)partition(2)%systemroot%=description

Windows 2000 Professional can use any of these formats in Boot.ini to locate the SystemRoot directory.

Multi Syntax

This form of the ARC pathname is referred to as Multi. On Microsoft Windows NT version 3.1, Multi syntax was only valid for Integrated Device Electronics (IDE), Enhanced Integrated Drive Electronics (EIDE), and Enhanced Small Device Interface (ESDI) disks. In Microsoft Windows NT version 3.5 and later (including Windows 2000), it is also valid for small computer system interface (SCSI) disks. It is not used with Windows 95 or Windows 98.

The Multi syntax instructs Windows 2000 Professional to rely on the system BIOS to load system files. This means that Ntldr is using interrupt (INT) 13 BIOS calls to find and load Ntoskrnl.exe and any other files it needs to start the system.

The following is an example of the Multi syntax :

multi( W )disk( X )rdisk( Y )partiton( Z )

Table 6.2 describes the parameters used in the Multi syntax:

Table 6.2 Multi Syntax Parameter Variables


Multi Parameter Definitions


The number of the adapter, usually 0.


Always 0.


The number for the disk on the adapter, usually between 0 and 3.


The partition number. All partitions that are in use receive a number. Primary partitions are numbered before logical drives.
The first valid number for Z is 1; W, X, and Y start at 0.

In theory, the Multi syntax can start Windows 2000 from any disk. However, this requires that all connected disks use the INT 13, and the system BIOS usually identifies only one disk adapter with INT13. For this reason, you can only use the Multi syntax to start Windows 2000 Professional from either of the two disks on the primary IDE or SCSI device or on the secondary IDE or SCSI device.

The use of the Multi syntax depends on the type of adapter that your computer uses. For example:

  • On IDE adapters, the Multi syntax works for up to four disks: two on primary and two on secondary IDE channels.

  • On SCSI adapters, the Multi syntax works for the first two disks on the first SCSI adapter (the adapter whose BIOS loads first).

  • With both SCSI and IDE adapters, the Multi syntax works for only the IDE disks on the first adapter.

SCSI Syntax

The SCSI syntax tells Windows 2000 Professional to load a SCSI device driver to access the boot partition.

The SCSI syntax is as follows:

scsi( W )disk( X )rdisk( Y )partition( Z )

Table 6.3 defines the parameters used in the SCSI syntax:

Table 6.3 SCSI Syntax Parameters


SCSI Parameter Definitions


The controller that is found.


The number of the physical disk attached to the computer.


The SCSI logical unit number (LUN) of the disk that contains the boot partition. This is typically 0.


The partition number. All partitions that are in use receive a number. Primary partitions are numbered before logical drives.
The first valid number for Z is 1; W, X, and Y start at 0.

Signature Syntax

The Signature syntax is equivalent to the SCSI syntax but is used instead to support the Plug and Play architecture in Windows 2000. Because Windows 2000 is a Plug and Play operating system, the SCSI controller number instance might vary each time you start Windows 2000, especially if you add new SCSI controller hardware after Setup.

The Signature syntax instructs Ntldr to locate the drive with a disk signature that matches the value in the parentheses, regardless of which SCSI controller number that the drive is connected to.

The naming format in Boot.ini starts with Signature syntax. For example:


The Signature syntax is used only if one of the following conditions exists:

  • The partition on which you installed Windows 2000 is larger than 7.8 gigabytes (GB) in size, or the ending cylinder number is higher than 1024 for that partition, and the system BIOS or boot controller BIOS does not support Extended INT13.

  • The drive on which you installed Windows 2000 is connected to a SCSI controller whose BIOS is disabled, so INT13 BIOS calls cannot be used during the startup process.

The Signature value is extracted from the MBR. This unique hexadecimal number is either written to the MBR during the text-mode portion of Setup or by a previous installation of Windows NT 4.0 or earlier.


Ntbootdd.sys is a copy of the SCSI device driver and resides on the system partition. Ntbootdd.sys is used when using the SCSI or Signature syntax in the file Boot.ini.

Additionally, if you have multiple SCSI controllers that use different device drivers, include only the controllers that are controlled by Ntbootdd.sys when determining the value of the W parameter. For example, if you have an Adaptec 2940 controller (which uses Aic78xx.sys) and an Adaptec 1542 controller (which uses Aha154x.sys), the value of W is always 0. Ntbootdd.sys changes in the following situations:

  • If you load Windows 2000 Professional from a disk on the Adaptec 2940 controller, Ntbootdd.sys is a copy of Aic78xx.sys.

  • If you load Windows 2000 Professional from a disk on the Adaptec 1542 controller, Ntbootdd.sys is a copy of Aha154x.sys.

Editing Boot.ini

When you install Windows 2000 Professional, Boot.ini sets the system and hidden attributes for you. You can edit the time-out and default parameters in Boot.ini by using the System option in Control Panel.



Back up the original Boot.ini file before making any changes.

To view Boot.ini, you must be able to view hidden files in My Computer.

To show hidden files in My Computer

  1. On the Tools menu, click Folder Options, and then click the View tab.

  2. Clear Hide protected operating system files .

  3. Click OK .

To edit the file Boot.ini, you can use Windows Explorer and double-click Boot.ini, or you can open any text editor to edit the file.

If you change the path to the Windows 2000 boot partition, edit the entries for both the default path and the operating system path. If you change only one, a new choice is added to the boot loader screen with the default designator next to it.