3Com 56K Command Reference Manual page 200

4 G
LOSSARY
Class 1/EIA-578
Class 2.0/EIA-592
CO
COM port
cps
CPU
CRC
cyclic redundancy
check (CRC)
data communications
data compression
data compression
table
data communication
equipment (DCE)
An American standard used between facsimile application programs
and facsimile modems for sending and receiving Class 1 faxes.
An American standard used between facsimile application programs
and facsimile modems for sending and receiving Class 2.0 faxes.
See central office.
See serial port, EIA-232.
See characters per second.
Central processing unit.
See cyclic redundancy check.
An error-detection technique consisting of a cyclic algorithm performed
on each block or frame of data by both sending and receiving
modems. The sending modem inserts the results of its computation in
each data block in the form of a CRC code. The receiving modem
compares its results with the received CRC code and responds with
either a positive or negative acknowledgment. In the ARQ protocol
implemented in 3Com high speed modems, the receiving modem
accepts no more data until a defective block is received correctly.
A type of communications in which computers and terminals are able
to exchange data over an electronic medium.
When the transmitting modem detects redundant units of data, it
recodes them into shorter units of fewer bits. The receiving modem
then decompresses the redundant data units before passing them to
the receiving computer.
A table of values assigned for each character during a call under data
compression. Default values in the table are continually altered and
built during each call: the longer the table, the more efficient
throughput gained.
If a destructive Break is sent during a call (see the &Y command),
causing the modems to reset the compression tables, you can expect
diminished throughput.
In this manual, the term applies to modems that establish and control
the data link via the telephone network.