The NT Loader functions as both a boot manager and a system loader. In operating systems released after Windows XP, BOOTMGR and winload.exe together replace NTLDR. If you have multiple operating systems installed and properly configured, NTLDR will show a boot menu when your computer starts, allowing you to choose which operating system should load.
NTLDR Errors
A common startup error in Windows XP is the “NTLDR is missing” error, which is sometimes seen when the computer tries to inadvertently boot to a non-bootable disc or floppy disk. However, sometimes the error is caused when attempting to boot to a corrupt hard drive when you really meant to boot to a disc or USB device running Windows or some other software. In this case, changing the boot order to the CD/USB device would likely fix it.
What Does NTLDR Do?
The purpose of NTLDR is so that a user can choose which operating system to boot into. Without it, there would be no way to direct the bootup process to load the OS you want to use at the time. This is the order of operations that NTLDR undergoes while booting: The menu options when selecting an operating system during bootup is defined in the boot.ini file. However, the boot options for non-NT versions of Windows can’t be configured through the file, which is why there needs to be an associated file that can be read to understand what to do next—how to boot to the OS.
More Information on NTLDR
If you only have one operating system installed on your computer, you won’t see the NTLDR boot menu. The NTLDR boot loader can run from not only a hard drive but also a disc, flash drive, floppy disk, and other portable storage devices. On the system volume, the NTLDR requires both the bootloader itself and ntdetect.com, which is used to find basic hardware information to boot the system. Like you read above, another file that holds important boot configuration information is boot.ini—NTLDR will choose the \Windows\ folder on the first partition of the first hard drive if that INI file is missing.
