Glossary
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Appendix B. Glossary
Absolute sector. All the sectors of a hard disk can be numbered sequentially, starting with
zero. Such numbered sectors are called absolute.
Active partition. One of the primary partitions of a hard disk is usually active. Default MBR
code tries to boot an operating system from the active partition of the first hard disk.
Letter assignment in Microsoft operating systems depends on which partitions are active.
Bad cluster. A cluster that contains bad sectors. Such a cluster cannot store information,
with possible corruption of the data.
Bad sector. A sector that cannot store the information written, for instance due to defects
or aging of the magnetic surface.
Booting is a procedure that is executed every time a computer is turned on or an
operating system finishes its work or when the reset button is pressed. Booting consists
of the following stages:
• Hardware diagnostics
• Memory check
• Built-in BIOS initialization
• Initialization of additional hardware components and their BIOSes (video, SCSI etc.)
• Booting an operating system
If a boot manager is installed on a computer, it is booted instead of an operating system.
Then the boot manager boots the user-selected operating system itself.
Boot record. The initial part of a partition that contains code and data necessary for
booting an operating system. May consist of one or several sectors. The first sector of a
boot record must end with the boot sector signature (0AA55h).
Boot sector is the first sector of a disk or a partition that contains the initial code for the
operating system booting. The boot sector must end with the 0AA55h signature.
Bootable disk is a disk from which an operating system may be booted. A bootable disk
must contain a boot sector of an operating system and the necessary system and
configuration files. The «bootable disk» term usually refers to diskettes and CD-ROMs.
Bootable partition. A partition that can host an operating system. At the beginning of such
a partition, there should be a boot record.
Cluster. Information storage unit in such file systems as FAT and NTFS. Every file
occupies a certain number of whole clusters, so the greater the cluster size, the higher
the losses due to file size adjustment, but the smaller the cluster the more space the
cluster distribution tables occupy.
