Back قطاع الإقلاع Arabic Загрузачны сектар Byelorussian Sector d'arrencada Catalan Boot sektor Czech Bootsektor German Bloque de arranque Spanish سکتور بوت Persian Secteur d'amorçage French Boot sektor Croatian Boot sector Italian

Boot sector

This article is about the generic concept of boot sectors. For the MBR in PCs, see Master Boot Record. For the VBR in PCs, see Volume Boot Record.
This example show various components of GNU GRUB distributed over sectors of a hard disk. When GRUB is installed on a hard disk, boot.img is written into the boot sector of that hard disk. boot.img has a size of only 446 bytes.

A boot sector is the sector of a persistent data storage device (e.g., hard disk, floppy disk, optical disc, etc.) which contains machine code to be loaded into random-access memory (RAM) and then executed by a computer system's built-in firmware (e.g., the BIOS).

Usually, the first sector of the hard disk is the boot sector, regardless of sector size (512 or 4096 bytes) and partitioning flavor (MBR or GPT).

The purpose of defining one particular sector as the boot sector is inter-operability between firmware and various operating systems.

The purpose of chain loading first a firmware (e.g., the BIOS), then some code contained in the boot sector, and then, for example, an operating system, is maximal flexibility.

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