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Glossary
D-5
MNP
: Protocols for error correction and data compression from Microcom, Inc.
Modem
: An artificial word concatenated from
mo
dulator and
dem
odulator. A modem
translates the digital signals received from its local DTE to analog signals which are
transmitted via a telephone line. At the other end, the analog signals are demodulated and
sent to the DTE as digital signals again.
Modulation
: Translating digital states to analog waveforms.
NuBus
: A bus system for plug-in cards for the Apple Macintosh computers.
Off-line
: A modem which is not connected to another modem is off-line.
On-line
: A modem which is engaged in a connection with another modem is on-line.
Originate
: In a modem connection, one modem must work in the originate mode, the
other in the answer mode.
Packed data
: Data from which redundant information has been removed. Some file
extensions denote packed files. Standard extensions are .ZIP, .ARC, .LZH, .TAR, .ZOO
and others. If you transfer packed data don't use MNP5 compression.
Parity
: A method to check whether a character has been correctly transmitted in
asynchronous transfer. Usual settings are even parity and odd parity. In a connection, the
modems at both ends must use the same parity settings.
Parity bit
: The parity bit is sent as additional information with the data bits in
asynchronous transfers. It controls the integrity of the transferred data. If parity is even,
the parity bit is set if an uneven number of data bits is sent in the character, resulting in an
even number of set bits.
PC
: Personal Computer - acronym for computers which are compatible with the IBM PC
or AT computers.
PHONE
: Jack to which a telephone set may be connected.
Processing unit
: A computer's brain. Here all the necessary calculations are performed.
The modems of the 2864 series are basically specialized computers.
Protocol, file transfer
: Many protocols have been developed to ensure reliable data
transfer at maximum speed, among them Xmodem, Ymodem, Zmodem and Kermit.
With modern modems, the use of integrated hardware protocols (MNP4 and V.42) is
recommended. The G-flavors of the above mentioned Ymodem and Zmodem allow
transfers of multiple files with no additional error correction.
Public Domain: A special form of distributing software. Public domain software authors
make no claim to commercialize their rights.
QUIET
: A state in the voice mode of ZyXEL modems. Quiet is detected after a long
pause in voice data.
RAM
: Random Access Memory - working memory. The modem uses it among many
other uses to store information on sent, but not yet acknowledged data.
Redundancy
: Extra data that does not generate additional information.