G
LOSSARY
7-1
Cross references are printed in
boldface
.
analog loopback
A modem self-test in which data from the keyboard or an internal test
pattern is sent to the modem's transmitter, turned into analog form, looped
back to the receiver, and converted back into digital form.
analog signals
A variety of signals and wavelengths that can be transmitted over
communications lines such as the sound of a voice over the phone line.
answer mode
The mode used by your modem when answering an incoming call from an
originating modem. The transmit/receive frequencies are the reverse of the
originating modem, which is in
originate mode
.
application
A computer program designed to perform a specific task or set of tasks.
Examples include word processing and spreadsheet applications.
ARQ
Automatic Repeat reQuest. A function that allows your modem to detect
flawed data and request that it be retransmitted. See
MNP
and
V.42
.
ASCII
American Standard Code for Information Interchange. A code used to
represent letters, numbers, and special
characters
such as $, !, and /.
asynchronous transmission
Data transmission in which the length of time between transmitted
characters
may vary. Because characters may not be transmitted at set
intervals,
start/stop
bits are used to mark the beginning and end of each
character.
Auto Answer
Sets the modem to pick up the phone line when it detects a certain number
of rings. See S-register S0 in the “Technical Reference” chapter of this
manual.
auto-dial
A process where your modem dials a call for you. The dialing process is
initiated by sending an ATDT (dial tone) or ATDP (dial pulse) command
followed by the telephone number. Auto-dial is used to dial voice numbers.
See command Dn.
baud rate
A term used to measure the speed of an analog transmission from one point
to another. Although not technically accurate, baud rate is commonly used
to mean
bit rate
.
binary digit
A 0 or 1, reflecting the use of the binary numbering system. Used because
the computer recognizes either of two states, OFF or ON. Shortened form
of binary digit is bit.
bit rate
Also referred to as transmission rate. The number of
binary digits
, or bits,
transmitted per second (
bps
). Communications channels using analog
modems are established at set bit rates, commonly 2400, 4800, 9600,
14,400, 28,800 and higher.
bits per second (bps)
The bits (
binary digits
) per second rate. Thousands of bits per second are
expressed as kilobits per second (kbps).
buffer
A temporary memory area used as storage during input and output
operations. An example is the modem's command buffer.
byte
A group of
binary digits
stored and operated upon as a unit. Most often
the term refers to 8-bit units or
characters
. One kilobyte (KB) is equal to
1,024 bytes or characters; 640 KB is equal to 655,360 bytes or characters.
carrier
The basic signal altered or modulated by the modem in order to carry
information.
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