6 Glossary

CMOS
Complementary Metal Oxide Semiconductor. A chip on the system board that contains
nonvolatile memory. CMOS is backed up by an internal lithium battery that preserves
clock/calendar data and system configuration parameters stored in CMOS.
codec
Coder-decoder. Used primarily with Internet phone and video conferencing products, this
software compresses digitized data and decompresses it at the other end, allowing for faster
data transfer and less delays
cold boot
Process of starting up the computer by turning on the power. If power is already on, the
process means to turn off the computer and turn it on again. A cold boot reinitializes all
devices.
compression
Any scheme for recording data with fewer bits. For example, stating how many times
something occurs can be shorter than stating each occurrence. It is shorter to say “print a
million white pixels” than to say “print white pixel number one, print white pixel number
two . . .”
D
default
The system’s factory setting for a specific device feature or system function. A setting that a
computer uses if it has not been modified by a user.
DIMM
Dual Inline Memory Module. Circuit board with pins connecting to different memory chips
on both sides of the board, which allows for wider and faster data transfer (128-bit). See
SIMMs.
DMA
Direct Memory Access. A method for transferring data, usually between memory and a disk
drive, without going through the CP U.
DMI
Desktop Management Interface. A standard for PCs that allows manipulation of PC
components over a network from a centralized location.
DRAM
Dynamic Random Access Memory. Memory used to store data in most computers. DRAM
is temporary and must be continually refreshed. It is only active when the computer is
turned on.
driver
A software program that enables peripheral devices (for example, printer, monitor, mouse,
CD-ROM drive) to work with computers.