APPENDIX I
GLOSSARY
A
ATTENUATION— Loss of communication signal
energy.
B
BASEBAND— The frequency band occupied by
individual information bearing signals before they
are combined with a carrier in the modulation
process.
BISYNC— Controlling of data transmission by timing
signals generated at the sending and receiving
stations.
BROADBAND— Transmission facilities whose
bandwidth is greater than that available on voice-
grade facilities.
BUS— Channel or path for transferring data and
electrical signals.
C
CARRIER SENSE MULTIPLE ACCESS
(CSMA)— A protocol that controls access to a
network’s bus.
CARRIER SENSE MULTIPLE ACCESS WITH
COLLISION AVOIDANCE (CSMA/CA)— A
protocol that requires carrier sense and in which a
data station that intends to transmit sends a jam
signal.
CARRIER SENSE MULTIPLE ACCESS WITH
COLLISION DETECTION (CSMA/CD)— A
protocol that requires carrier sense and in which a
transmitting data station that detects another signal
while transmitting, stops sending, sends a jam
signal, and then waits for a variable time before
trying again.
CLEAR TO SEND— A hardware signal sent from a
receiver to a transmitter to indicate that the
transmitter can begin sending.
CROSSTALK— The disturbance caused in a circuit by
an unwanted transfer of energy from another
circuit.
F
FILTER— A device or program that separates data,
signals, or material in accordance with specified
criteria.
FIREWALL— One or more components that control
the flow of network traffic between networks.
H
HANDSHAKING— The process through which the
rules for exchanging data over a communications
line are defined for the two devices involved.
I
IMPEDANCE— A measure of electrical resistance.
INTERNATIONAL STANDARDS ORGANIZA-
TION (ISO)— The international agency
responsible for developing standards for
information exchange.
INTERRUPT REQUEST LINES— Physical
connections between hardware devices and the
interrupt request.
L
LINE DRIVER— A component that includes a
transmitter and a receiver.
LINK— The communications media used to connect
nodes.
M
MULTITASKING— A mode of operation that
provides for concurrent performance of two or
more tasks.
N
NETWORK INTERFACE CARD (NIC)— The
expansion card that allows the workstation to
communicate with the network.
AI-1
