G
LOSSARY
Glossary-3
B
backup: A duplicate copy of files kept
as a spare in case the original is
destroyed.
batch file: A file that can be executed
from the system prompt containing a
sequence of operating system com-
mands or executable files. See also
AUTOEXEC.BAT.
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 firm-
ware.
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.
board: A circuit board. An internal
card containing electronic compo-
nents, 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.
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.
bus: An interface for transmission of
signals, data or electric power.
byte: The representation of a single
character. A sequence of eight bits
treated as a single unit; also the
smallest addressable unit within the
system.
C
cache memory: High speed memory
which stores data that increases
processor speed and data transfer
rate. When the CPU reads data from
main memory, it stores a copy of this
data in cache memory. The next time
the CPU needs that same data, it looks
for it in the cache memory rather than
the main memory, which saves time.
The computer has two cache levels.
Level one is incorporated into the
processor and level two resides in
external memory.
cache memory
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