Setup and Startup

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After the computer finishes the POST, the system BIOS attempts to start an operating system. The sequence that the BIOS follows depends on the BIOS configuration. For example, if the BIOS search order is set to A and then C (A, C), the BIOS searches the floppy disk drive for a bootable disk. If drive A contains a bootable floppy disk, the BIOS loads its first sector (the partition boot sector) into memory. If the floppy disk is not bootable, the following error message appears.

Non-system disk or disk error

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If the BIOS does not find a floppy disk in the drive, it then searches for the active partition on the hard disk drive. If there is no system partition on the first hard disk, the master boot record (MBR) displays one of the following errors:

  • Invalid partition table

  • Error loading operating system

  • Missing operating system

When the active partition of the hard drive is found, the system BIOS reads the MBR and loads it into memory. The MBR then scans the partition table for the system partition information. When the system partition information has been read, it loads sector 0 of the system partition into memory and starts it.

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Note

Sector 0 of the system partition can be a utility, a diagnostic program, or a partition boot sector that contains the startup code for the operating system.

The system partition must be on the first physical disk and contain the system startup files listed in Table 6.1.

Table 6.1 Windows 2000 Startup Files

File Name

Location

Ntldr

Root of startup disk

Boot.ini

Root of startup disk

Bootsect.dos

Root of startup disk (on multiple-boot systems)

Ntdetect.com

Root of startup disk

Hyberfil.sys

%systemdrive%

Ntbootdd.sys

Root of startup disk (for SCSI and some large IDE drives)

Ntoskrnl.exe

%systemroot%\System32

Hal.dll

%systemroot%\System32

System key

%systemroot%\System32\Config

Device drivers

%systemroot%\System32\Drivers

Cdldr

Root of startup disk

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Note

If the name of the path in Boot.ini uses small computer system interface (SCSI) syntax, the Ntbootdd.sys must be in the root folder of the system partition.

The boot partition can be on the same partition as the system partition, on a different partition, or on a different hard disk.

For the most part, the MBR is independent of the operating system. For example, the MBR can start Windows NT, Windows 95, Windows 98, MS-DOS, Microsoft Windows 3. x , and Windows 2000 Professional. However, after boot sector 0 has been loaded into memory, the partition boot sector is dependent on both the operating system and the file system. The Windows 2000 partition boot sector performs the following functions:

  • Reads the file system to find the bootstrap loader.

  • Loads the bootstrap loader into memory.

  • Starts the bootstrap loader.