57. first sector of a harddrive

• What is located on the first sector of any hard disk drive? What is contained in it?

  • The first 512 bytes on a hard drive -- aka Sector Zero -- contain the Master Boot Record (MBR).

  • The MBR contains the boot code and the partition table.

  • The partition table identifies the file system on the partitions on the disk; there must be at least one.

  • The boot code processes the partition table to identity which partition is bootable; control then transfers to the first sector, called the boot sector, of the active partition (there can be only one). The boot sector is operating system-specific.