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LAPM . Link Access Protocol Modem. A V.42 ARQ type of error
correction protocol which is controlled by S-Register 46, where LAPM
may be activated with or without V.42bis data compression.
leased line . Also referred to as a private line. A leased line is obtained
from a communications company (carrier) to provide a transmission
medium between two points. The line consists of a permanent
dedicated circuit between two points, or to set of previously arranged
points. The cost of the line is usually based on the distance between
locations. This is in contrast to switched or dial-up lines, which can be
connected to any point on the network.
line modulation . The means by which a carrier is varied to represent
a signal carrying information. In a modem, the user ’s digital data is
used to modulate the modem’s transmitter ’s carrier or carrier to
allow the digital signal to be carried over analog facilities.
long space disconnect . Determines whether or not modem
disconnects when it receives a continuous break from a remote
modem. Controlled by the ATY command.
loopback tests . There are four types of loopback tests which are as
follows: (1) the local digital loopback tests the operation of the DTE,
including whether or not data is leaving the terminal or computer
port; (2) the local analog loopback tests the digital and analog circuits
of the modem; (3) the remote digital loopback checks the operating
condition of the line and remote modem; (4) the remote analog
loopback tests the line to the remote modem.
M
MNP
. Microcom Networking Protocol. A series of data
communications protocols developed by Microcom for full-duplex,
error-free communications.
make/break ratio . The &P command controls the ratio of the off-hook
(make) to on-hook (break) interval used by the modem when it pulse
dials. &P0 selects a 39%/61% make/break ratio for use in the U.S.
&P1 selects a 33%/67% make/break ratio for use in the United
Kingdom and Hong Kong. The &P command is NOT allowed in
some countries.
HOMEOFF.PM6 5/9/97, 9:15 AM 66