Quick Reference Guide

Glossary 287
cpi
Abbreviation for characters per inch.
CPU
Abbreviation for central processing unit. See also
microprocessor.
CRC
Abbreviation for cyclic redundancy code, which is a
number derived from, and stored or transmitted with,
a block of data in order to detect corruption. By
recalculating the CRC and comparing it to the value
originally transmitted, the receiver can detect some
types of transmission errors.
CSR
Abbreviation for certificate signing request.
cursor
A marker, such as a block, underscore, or pointer that
represents the position at which the next keyboard or
mouse action will occur.
DAT
Acronym for digital audio tape.
dB
Abbreviation for decibel(s).
dBA
Abbreviation for adjusted decibel(s).
DC
Abbreviation for direct current.
device driver
A program that allows the operating system or some
other program to interface correctly with a peripheral
device, such as a printer. Some device drivers—such as
network drivers—must be loaded from the
config.sys
file (with a device= statement) or as memory-resident
programs (usually, from the
autoexec.bat file).
Others—such as video drivers—must load when you
start the program for which they were designed.
DHCP
Abbreviation for Dynamic Host Configuration Protocol,
a protocol that provides a means to dynamically
allocate IP addresses to computers on a LAN.
DIMM
Acronym for dual in-line memory module. A small
circuit board containing DRAM chips that connects to
the system board.
DIN
Acronym for Deutsche Industrie Norm, which is the
standards-setting organization for Germany. A DIN
connector is one that conforms to one of the many
standards defined by DIN. DIN connectors are used
widely in personal computers. For example, the
keyboard connector for personal computers is a
DIN connector.
DIP
Acronym for dual in-line package. A circuit board, such
as a system board or expansion card, may contain
DIP switches for configuring the circuit board.
DIP switches are always toggle switches, with an on
and an off position.
directory
Directories help keep related files organized on a disk
in an hierarchical, inverted tree structure. Each disk has
a root directory; for example, a
C:\> prompt normally
indicates that you are at the root directory of hard drive
C. Additional directories that branch off of the root
directory are called subdirectories. Subdirectories may
contain additional directories branching off of them.
display adapter
See video adapter.
DKS
Abbreviation for dynamic kernel support.