HD Doctor Blog

The master boot record (MBR) is a small program typically located on the first sector of the hard drive.

It examines the partition table to determine which partition to boot first and then executes the proper commands to run the operating system installed on that partition. If the boot sector becomes corrupt or is overwritten by another operating system, Windows XP will not be able to load. Fortunately, the Windows XP installation CD contains an application that can fix damaged boot sectors.

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What is the MBR?

A master boot record (MBR), or partition sector, is the 512-byte boot sector that is the first sector ("LBA Sector 0") of a partitioned data storage device such as a hard disk. (The boot sector of a non-partitioned device is a Volume Boot Record. These are usually different, although it is possible to create a record that acts as both; it is called a multi boot record.) The MBR may be used for one or more of the following:

• Holding a disk’s primary partition table
• Bootstrapping operating systems, after the computer’s

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