Appendix B. Glossary
Absolute sector. All the sectors of a hard disk can be numbered sequentially,
starting with zero. Thus 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 de-
pends on what partitions are active.
Bad cluster. A cluster that contains bad sectors. Such cluster cannot store
useful information.
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 operation system.
If a boot manager is installed on a computer, then it is booted instead of an
operating system. Then the boot manager boots the user-chosen operating
system itself.
Boot record. The initial part of a partition that contains code and data neces-
sary for booting an operating system. May consist of one or several sectors.
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 operation system booting. Boot sector must end with 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.
76 Appendix B : Glossary
