US Robotics COURIER - APPENDIX G. GLOSSARY

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COURIER HIGH SPEED MODEMS
APPENDIX
G. GLOSSARY
Cross-references in the following definitions are printed in boldface.
Analog Loopback
A modern self-test in which data from the keyboard is sent to the
modem's transmitter, modulated into analog form, looped back
to the receiver, demodulated into digital form, and returned to
the screen for verification.
Analog Signals
Continuous, varying waveforms such as the voice tones carried
over phone lines. Contrast with digital signals.
Answer Mode
A state in which the modern transmits at the predefined high
frequency of the communications channel and receives at the
low frequency. The transmit/receive frequencies are the reverse
of the calling modern which is in Originate mode.
Application (application program)
ARQ
A computer program designed to perform a specific function,
such as a word processor or a spreadsheet.
Automatic Repeat Request. A general term for error control
protocols which feature error detection and automatic retrans-
mission of defective blocks of data. See HST, MNP, and V.42.
ASCII
American Standard Code for Information Interchange. A 7-bit
binary code (O's, 1 's) used to represent letters, numbers, and
special characters such as $, !, and I. Supported by almost every
computer and terminal manufacturer.
Asymmetrical Modulation
A duplex transmission technique which splits the communi-
cations channel into one high speed channel and one slower
channel. During a call under asymmetrical modulation, the
modern with the greatest amount of data to transmit is allocated
the high speed channel. The modem with less data is allocated
Glossary G-1