How does boot sector work

MBR doesn't belong to any operating system and doesn't change with the changes of operating systems. Even MBR changes, it has common guide characteristic rather than entrains the nature of operating system. MBR is called to be loaded into memory and to play a role first. Then it will transfer control right to operating system in active partition. The bytes taken up by master boot program of hard disk is from H to 01BDH.

Master boot code includes small pieces of executing code. When you start PC, system will firstly test hardware devices. After the test is successful, boot loader INT 19H will be activated.

There are many types, but there are two main ones: the master boot record and the volume boot record. A master boot record exists on a drive that has been partitioned, and it usually finds the active partition and run its own volume boot record.

The volume boot record, in turn, often contains code to run the operating system on the computer. Hard disk drives contain a master boot record as their first boot sector, while floppy disks or USB disks usually only contain a volume boot record as their first boot sector, as they cannot be partitioned. The BIOS of a computer, the part that runs before anything else, immediately looks to this sector of a drive, whether it is a master or a volume, for instructions on what to do next. The boot sector can actually include instructions to do fairly complex things, which comes in use for things like giving a user the option to run one of many operating systems, but also means there is the potential for abuse in the form of viruses.

To be a boot sector, the sector need meet only one criteria, which is to have a signature of 0xAA55 as its final two bytes. Boot Sector. Techopedia Explains Boot Sector. What Does Boot Sector Mean? A boot sector is also known as a boot block. Techopedia Explains Boot Sector A boot sector stores boot record data that gives instructions to a computer when it is started.

The boot sector is generally located at the start of a disk for rapid computer access. Synonyms Boot Block. Share this Term. Tech moves fast! Stay ahead of the curve with Techopedia! Join nearly , subscribers who receive actionable tech insights from Techopedia.