US Robotics COURIER HST User'smanual page 117

COURIER HST
Error Control
Flow Control
Frame
Full Duplex
Half Duplex
HST
Local Echo
MNP
G-4
Various techniques which check the reliability of characters
(Parity) or blocks of data. The Courier's error control proto-
col provides error control through error detection (CRC) and
retransmission of errored frames
(ARQ).
A mechanism that compensates for differences in the flow of
data input to and output from a modem or other device.
A data communications term for a block of data with header
and trailer information attached. The added information usu-
ally includes a frame number , block size data, error-check
codes, and Start/End data.
Signal flow in both directions at the same time. In micro-
computer communications, may refer to the suppression of
the online Local Echo. The receiving computer may provide
a
Remote Echo.
Signal flow in both directions, but only one way at a time.
In microcomputer communications, may refer to activation
of the online Local Echo, which causes the modem to send
a copy of the transmitted data to the screen of the sending
computer.
High Speed Technology, part of the trademark for
USRobotics'
USR-HST,
a proprietary signaling scheme,
design and protocol for 9600 bps modems.
USR-HST
incor-
porates trellis-coded modulation, for greater immunity from
variable phone line conditions, and asymmetric modulation
for more efficient use of the phone channel. HST also repre-
sents the enhanced error control protocol at 9600 bps that
is similar to and compatible with MNP error control at
2400/ 1200 bps.
A modem feature that enables the modem to send copies
of keyboard commands and transmitted data to the screen.
When the modem is in Command Mode (not online to
another system) the local echo is invoked through the A TE 1
command. The command causes the modem to display your
typed commands. When the modem is online to another sys-
tem, the local echo is invoked through the ATF0 command.
This command causes the modem to display the data it
transmits to the remote system.
Microcom Networking Protocol. An error control proto-
col developed by Microcom, Inc. and now in the public
domain. The protocol ensures error-free transmission up to