OS Loads

During POST, the BIOS also locates the system boot device—such as the floppy

disk, CD-ROM, or hard drive—that contains the OS. Once the POST process

completes successfully, the BIOS then passes control of the boot process over to

the PC’s OS. The exact loading process differs from one OS to the next, but in

general, one or more vital system files such as NTLDR (pronounced “NT

loader”) load into memory and start the ball rolling. Things move fast from

there, as the OS load its core files, drivers, and services into RAM.The next thing

you know, you’re looking at your desktop and hearing the soothing strains of

the Windows logon sound file.