Editing NTLDR (section)

==Startup process==
{{further|Windows NT startup process}}
When a PC is powered on its [[BIOS]] follows the configured boot order to find a bootable device. This can be a harddisk, floppy, CD/DVD, network connection, USB-device, etc. depending on the BIOS. In the case of a floppy the BIOS interprets its boot sector (first sector) as code, for NTLDR this could be a NTLDR boot sector looking for the <code>ntldr</code> file on the floppy. For a harddisk the code in the [[Master Boot Record]] (first sector) determines the active partition. The code in the boot sector of the active partition could then be again a NTLDR boot sector looking for <code>ntldr</code> in the root directory of this active partition. In a more convoluted scenario the active partition can contain a Vista boot sector for the newer Vista boot manager with an <nowiki>{ntldr}</nowiki> entry pointing to another partition with a NTLDR boot sector.<ref>{{cite web
|url=https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc721886(v=ws.10)
|title=Boot Configuration Data Editor Frequently Asked Questions
|work=Windows Server
|year=2007
|publisher=[[Microsoft Learn]]
|access-date=2024-01-04}}</ref>

When booting, the loader portion of NTLDR does the following in order:

#Accesses the file system on the boot drive (either [[File Allocation Table|FAT]] or New Technology File System, [[NTFS]]).
#If Windows was put in the hibernation state, the contents of ''hiberfil.sys'' are loaded into memory and the system resumes where it left off.
#Otherwise, reads ''boot.ini'' and prompts the user with the boot menu accordingly.
#If a non NT-based OS is selected, NTLDR loads the associated file listed in ''boot.ini'' (''bootsect.dos'' if no file is specified or if the user is booting into a DOS based OS) and gives it control.
#If an NT-based OS is selected, NTLDR runs ''[[ntdetect.com]]'', which gathers information about the computer's hardware. (If ''ntdetect.com'' hangs during hardware detection, there is a debug version called ''ntdetect.chk'' that can be found on Microsoft support.<ref>{{cite web |url=http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/ntdetect-o.asp |title=Ntdetect.com (Installd.cmd)  |website=[[Microsoft]] |archive-url=https://web.archive.org/web/20060206082801/http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/ntdetect-o.asp |archive-date=2006-02-06 |url-status=dead}}</ref>)
#Starts ''[[ntoskrnl.exe]]'', passing to it the information returned by ''ntdetect.com''.<ref>{{cite book| author=Microsoft| author-link=Microsoft| year=2000| title=Windows 2000 Professional Resource Kit| edition=1st| publisher=Microsoft Press| location=Redmond, WA| isbn=1-57231-808-2| url-access=registration| url=https://archive.org/details/microsoftresourc00micr}}</ref>