3Com Courier, Справочник

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2 G
LOSSARY
dynamically reverse the channels during a call if the volume of data
transfer changes.
asynchronous
transmission
Data transmission in which the length of time between transmitte
characters may vary.
Because the time lapses between transmitted characters are not
uniform, the receiving modem must be signaled as to when the data
bits of a character begin and when they end. The addition of start an
stop bits to each character serves this purpose.
auto answer A feature in modems enabling them to answer incoming calls over the
phone lines without the use of a telephone receiver.
auto dial A feature in modems enabling them to dial phone numbers over the
phone system without the use of a telephone transmitter.
Automatic Repea
Request (ARQ)
A general term for error control protocols which feature error detectio
and automatic retransmission of defective blocks of data. See HST,
MNP, and V.42.
baud rat The number of discrete signal events per second occurring on a
communications channel. Although not technically accurate, baud rate
is commonly used to mean bit rate.
binary digit (bit) A 0 or 1, reflecting the use of a binary numbering system (only tw
digits). Used because the computer recognises either of two states, OFF
or ON. Shortened form of binary digit is bit.
BISYNC Binary Synchronous Control. A protocol developed by IBM for software
applications and communicating devices operating in synchronous
environments. The protocol defines operations at the link level of
communications, for example, the format of data frames exchange
between modems over a phone line. See Protocol, HDLC, SDLC.
bit See binary digit.
bit-mapping A technique that lets one decimal number (in this case, a number
between 0 and 255) stand for up to 8 separate binary settings.
bit rat The number of binary digits, or bits, transmitted per second (bps).
Communications channels using telephone channel modems are
established at set bit rates, commonly 300, 1200, 2400, 4800, 9600,
14400, and 28800.