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COMSPHERE 3821Plus Modem
Glossary-2 February 1998 3821-A2-GB20-30
automatic answer A capability to respond to a call received over a dial line.
automode To change modulations or rates within a modulation when modems first connect. A
modem may automode to a different modulation than what it is configured for due to the
limitations of the remote modem, or automode to a lower rate due to unfavorable VF line
conditions during connection.
autorate To adjust to varying VF line conditions by changing the data rate to a higher or lower
rate after connection. The lowest rate the modem autorates to is 4800 bps; the highest
possible rate depends on the modulation the modems connected with. In V.34, the
modems may autorate asymmetrically.
baud A unit of signaling speed that is equal to the number of symbols per second. This is not
necessarily the same as bits per second, although the terms are frequently interchanged.
Bisync Binary Synchronous Communications. An IBM communications protocol that has
become an industry standard. It uses a defined set of control characters and control
character sequences for synchronized transmission of binary-coded data between stations
in a data communications system.
bit A contraction of binary digit. A bit, which is the smallest unit of information, represents
a one or a zero (sometimes called mark or space).
bps Bits per second. Indicates the speed at which bits are transmitted across a data
connection.
buffer A storage device used to compensate for differences in the data flow rate when
transmitting data from one device to another.
byte A sequence of successive bits (usually eight) handled as a unit in data transmission.
CCITT An advisory committee (Consultative Committee on International Telephone and
Telegraph) established by the United Nations to recommend communications standards
and policies. Now called ITU-T.
character A letter, figure, number, punctuation, or other symbols.
character echo A way to check the accuracy of data transmission by sending (displaying) all the
characters being transmitted to the monitor.
Class 1 fax A fax modem standard. Under Class 1 computer software handles most of the protocol,
compression, and conversion tasks.
Class 2 fax A fax modem standard. Under Class 2 the modem handles most of the protocol,
compression, and conversion tasks as well as modulation, leaving the computer free for
other work.
command line Contains the command(s) instructing the modem to perform a function. Command lines
begin with the AT prefix (unless disabled), and are executed when you press the Return
key.
Command mode One of two general modem operating modes. When in Command mode, the modem
accepts commands instead of transmitting or receiving data.