User’s Manual Glossary-3
Glossary
alternating current (AC): Electric current that reverses its direction of flow at
regular intervals.
analog signal: A signal whose characteristics such as amplitude and frequency
vary in proportion to (are an analog of) the value to be transmitted. Voice
communications are analog signals.
application: A group of programs that together are used for a specific task such
as accounting, financial planning, spreadsheets, word processing and games.
ASCII: American Standard Code for Information Interchange. ASCII code is a set
of 256 binary codes that represent the most commonly used letters, numbers,
and symbols.

B

backup: A copy of a file, usually on a removable disk, kept in case the original file
is lost or damaged.
binary: The base two number system composed of zeros and ones (off or on),
used by most digital computers. The right-most digit of a binary number has
a value of 1, the next a value of 2, then 4, 8, 16, and so on. For example, the
binary number 101 has a value of 5. See also ASCII.
BIOS: Basic Input/Output System. The firmware that controls data flow within the
computer. See also firmware.
bit: Derived from “binary digit”, the basic unit of information used by the computer.
It is either zero or one. Eight bits is one byte. See also byte.
Bluetooth: A short-range radio technology designed to simplify wireless
communication among computers, communication devices and the Internet.
board: A circuit board. An internal card containing electronic components, called
chips, which perform a specific function or increase the capabilities of the
system.
boot: Short for bootstrap. A program that starts or restarts the computer. The
program reads instructions from a storage device into the computer’s memory.
boot disk: See system disk.
bootable disk: See system disk.
bps: Bits per second. Typically used to describe the data transmission speed of a
modem.
buffer: The portion of the computer’s memory where data is temporarily stored.
Buffers often compensate for differences in the rate of flow from one device to
another.