262 Glossary

B

backup — A copy of a file, usually on a removable disk, kept in case the

original file is lost or damaged.

 

 

basic input/output system (BIOS) — See BIOS.

 

baud rate — The speed at which a communication device, such as a

 

printer or modem, transmits information. Baud rate is the number of

 

signal changes per second (not necessarily the same as bits per

 

second). See also bits per second.

 

BIOS (basic input/output system) — Basic instructions, stored in read-

 

only memory (ROM), containing the information the computer

 

needs in order to check hardware and load the operating system

 

when you start up the computer.

 

bits per second (bps) — A way of measuring the speed at which

 

information is passed between two devices. The basic measure used

 

in modem communications, bps is similar, but not identical, to the

 

baud rate. See also baud rate.

 

boot — To start the computer. The term “boot” originates from bootstrap

 

program (as in “pulling itself up by its bootstraps”), a program that

 

loads and initializes the operating system. See also reboot.

 

boot disk — See system disk.

 

boot priority (startup sequence) — The order in which the computer

 

accesses its disk drives to locate the startup files. Under the default

 

startup sequence, the computer looks for the startup files in the

 

diskette drive before checking the hard disk.

 

bus — An electrical circuit that connects the central processing unit

 

(CPU) with other parts of the computer, such as the video adapter,

 

disk drives, and ports. It is the pathway through which data flows

 

from one device to another. See also bus speed, frontside bus.

 

bus speed — The speed at which the central processing unit (CPU)

C

communicates with the other parts of the computer.
cache — A section of very fast memory in which frequently used

 

 

information is duplicated for quick access. Accessing data from

 

cache is faster than accessing it from the computer’s main memory.

 

See also CPU cache, L1 cache, L2 cache.

 

CD — An individual compact disc. See also CD-ROM.