Definitions of Master boot record on the Web:
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 ...
The first sector of a hard disk in a PC. It contains the Partition Table. The very first sector on a hard drive. ...
(MBR) The first logical sector on a disk, this is (usually) where the BIOS looks to load a small program that will boot the computer.
A virus infecting the system’s master boot record on hard drives and boot sector on diskettes. This virus corrupts the system at a low level and ...
MBR - See Boot Sector
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