NT loader

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NTLDR

Ntldr.png
Basic data

developer Microsoft
operating system Windows NT
category Boot manager
License proprietary
German speaking Yes

NT loader , shortly NTLDR , the boot manager for Windows NT - systems up to and including Windows Server 2003 from Microsoft . It reads its configuration from the text file boot.ini. It is necessary because the Windows registration database is only available after the operating system has started. It also enables editing outside of Windows. The NTLDR has been replaced by the Bootmgr from Windows Vista onwards .

Function and intended use

The configuration file is located next to the files ntldrand ntdetect.comand, if applicable ntbootdd.sys, bootsect.dosin the root directory of the active primary partition (usually C:\) and its possible parameters differ depending on the Windows version . This boot manager has become necessary because Windows NT no longer has a DOS kernel and a possibility must be created to influence the start behavior via parameters before Windows starts. Since the DOS-based and NT Windows systems are functionally very different, this should also make it possible to operate different Windows versions in parallel.

A dual boot scenario that used to be very common is the classic parallel operation of Windows 9x with Windows NT 3.5 or 4.0 . Since NT-based Windows operating systems up to version 4.0 had little multimedia support and did not support Plug and Play and therefore USB and FireWire were never implemented, it made sense to start Windows 95 or 98 for scanning or multimedia applications, for the daily work of the However, stability because of Windows NT use.

The NTLDR is only used on x86- based computers. RISC-based computers have firmware that implements a boot menu , enabling multiple operating systems to be started. The file osloader.exe, which only exists on RISC-based computers, starts the operating system directly using parameters that are passed to it by the firmware.

Structure of the boot.ini

This boot.iniis the configuration file of the boot manager ntldr. This file is necessary because the Windows registry is only available after the operating system has started. The path information in the boot.inicorresponds to the conventions of RISC computers that are specified in the ARC standard.

Example configuration

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Workstation, Version 4.0"
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Workstation, Version 4.0 [VGA-Modus]" /basevideo /sos
C:\="MS-DOS"
C:\bootsect.deb="Ubuntu"
[boot loader]
initiates the configuration file
timeout = xx
Specifies the time in seconds that the system waits until the preset operating system is started if there are several entries (default value: 30)
default = xx
specifies the standard operating system to be started
[operating systems]
from here the individual entries of the operating systems are listed, several of the following entries can be listed; if there is only one entry, the boot menu is not displayed when the computer starts; From Windows 2000 onwards, only one system entry is created for a standard installation without any other recognized operating systems.
multi (0) disk (0) rdisk (1) partition (1) \ Windows directory = "Text in the boot menu" [Options ...]
starts a Windows installation via the system BIOS (INT 13)
scsi (c) disk (d) rdisk (l) partition (p) \ Windows directory = "Text in the boot menu" [Options ...]
starts a Windows installation via an explicit driver
signature (c) disk (d) rdisk (l) partition (p) \ Windows directory = "Text in the boot menu" [Options ...]
starts a Windows installation via an explicit driver
C: \ = "MS-DOS"
offers a system start independent of the "ntldr" (here: system transfer to the DOS start files via their as bootsect.doswell as the boot.inisaved boot sector), which is usually only possible for DOS, DOS-based Windows systems and not Microsoft systems
C: \ bootsect.deb = "Ubuntu"
offers a system start independently of the ntldr(here: system transfer to the start files of a Linux via their as bootsect.debwell as the boot.inisaved boot sector)

Explanation for example: The boot loader takes over the start of Windows NT (start directory after the partition information ) until the start files and drivers are loaded ; for a DOS or DOS-based Windows, the boot loader transfers this work to the DOS start files, to which the following Entry references. However, only one DOS and one NT system can be started per partition; third-party operating systems such as Linux or Netware are not officially supported. Installing several NT systems or several Windows 3.x and Windows 9x versions on the same computer also requires a deeper knowledge of the behavior and technical requirements of the various Windows versions and is not possible without manual intervention.

NTLDR starts from hard disk or floppy disk without changing the master boot record , in contrast to some other boot loaders, e.g. B. under Linux. More demanding configurations can be done better and more conveniently (or at all) with boot managers from other manufacturers and partitioning programs. However, they are not a complete replacement for NTLDR, as it is permanently integrated into the NT system for loading the start files. Most boot managers (e.g. GRUB and LILO for Linux ) can usually run in parallel without any problems.

Locate the boot partition

Starting via the system BIOS (INT 13)

multi (0) disk (0) rdisk (d) partition (p) \ Windows directory = "Text in the boot menu" [Options ...]

d is the logical number of the disk from the BIOS point of view. 0 for the first disk (0x80), 1 for the second disk (0x81) etc. This has nothing to do with master, slave or SCSI ID. At 3 it usually ends.

p is the number of the partition on the disk. The first primary partition is 1. This is followed by all other primary partitions followed by the extended ones. The extension partitions themselves (types 0x05 and 0x0F) do not count.

Windows directory is the% SystemRoot% of the installation concerned, without a drive letter.

See below for options .

Start via an explicit driver

scsi (c) disk (d) rdisk (l) partition (p) \ Windows directory = "Text in the boot menu" [Options ...]

For this variant, the file must be ntbootdd.sysin the main directory of the start partition - that is, where it boot.iniis. This file must be a (renamed) copy of the driver required to address the desired hard disk %SystemRoot%\System32\Drivers\. This is usually the case with IDE disks atapi.sys, unless the controller used requires a manufacturer-specific driver (always with SCSI).

c
is the number of the controller to be used, starting with 0. So e.g. B. 0 for the first IDE channel. Only the controllers that are supported by the respective driver count.
d
is the ID of the hard drive. With IDE: 0 = master, 1 = slave, with SCSI: SCSI-ID.
l
is the LUN (Logical Unit Number) - usually 0
p
and everything else is identical to the multi () syntax above.

The main options

/FastDetect
switches off the hardware detection NTDETECT.COMwhich was still used in Windows NT 4.0.
/NoGUIBoot
starts Windows without graphical output. No messages are displayed during the boot process.
/BootLogo
in connection with /NoGUIBootyou can change the bootscreen without special tools; this has to in the following format in the Windows directory be present: BOOT.BMP; 640 × 480 pixels; 16 colors.
/SOS
shows all drivers while loading; then a start screen similar to Windows NT appears; This does not mean that these drivers are also necessarily started by Windows. This can be useful for troubleshooting.

Individual references and sources

  1. ↑ Windows NT Resource Kit - Chapter 19 - What Happens When You Start Your Computer . Retrieved June 8, 2012.
  2. ↑ Microsoft Knowledge Base - BOOT.INI and ARC Path Naming Conventions and Usage . Retrieved March 4, 2013.

Web links