Multitech MultiModem MT4X56USB User Manual page 80

MultiModemUSB User Guide
A
Analog signal: A waveform which has amplitude, frequency and phase, and which takes on a range of values between its
maximum and minimum points.
Analog Transmission: One of two types of telecommunications which uses an analog signal as a carrier of voice, data,
video, etc. An analog signal becomes a carrier when it is modulated by altering its phase, amplitude and frequency to
correspond with the source signal. Compare with digital transmission.
Application Program Interface (API): A software module created to allow dissimilar, or incompatible applications programs
to transfer information over a communications link. APIs may be simple or complex; they are commonly required to link PC
applications with mainframe programs.
ASCII (American Standard Code for Information Interchange) (pronounced "askey"): A binary code for data that is
used in communications and in many computers and terminals. The code is used to represent numbers, letters, punctuation
and control characters. The basic ASCII code is a 7-bit character set which defines 128 possible characters. The extended
ASCII file provides 255 characters.
Asynchronous Transfer Mode (ATM): A very high-speed method of transmission that uses fixed-size cells of 53 bytes to
transfer information over fiber; also known as cell relay.
AT Commands: A standard set of commands used to configure various modem parameters, establish connections and
disconnect. The "AT" is used to get the "attention" of the modem before the actual command is issued.
Availability: The measure of the time during which a circuit is ready for use; the complement of circuit "outage" (100%
minus % outage = % available).
B
Babble: unexpected bus activity that persists beyond a specified point in a frame.
Backbone: 1. A set of nodes and their interconnecting links providing the primary data path across a network. 2. In a local
area network multiple-bridge ring configuration, a high-speed link to which the rings are connected by means of bridges. A
backbone may be configured as a bus or as a ring. 3. In a wide area network, a high-speed link to which nodes or data
switching exchanges (DSEs) are connected. 4. A common distribution core that provides all electrical power, gases,
chemicals, and other services to the sectors of an automated wafer processing system.
Background: An activity that takes place in the PC while you are running another application. In other words, the active
user interface does not correspond to the 'background' task.
Bandwidth: the amount of data transmitted per unit of time, typically bits per second (bps) or bytes per second (Bps).
Bell Operating Companies (BOC): The family of corporations created during the divestiture of AT&T. BOCs are
independent companies which service a specific region of the US. Also called Regional Bell Operating Companies
(RBOCs).
Bell Pub 41450: The Bell publication defining requirements for data format conversion, line conditioning, and termination
for direct DDS connection.
Bell Pub 62310: The Bell publication defining requirements for data format conversion, line conditioning, and termination
for direct DDS connection.
Binary Synchronous Communication (BSC): A form of telecommunication line control that uses a standard set of
transmission control characters and control character sequences, for binary synchronous transmission of binary-coded data
between stations.
Bit (Binary digit): A bit is the basis of the binary number system. It can take the value of 1 or 0. Bits are generally
recognized as the electrical charge generated or stored by a computer that represent some portion of usable information.
Bps (bits per second): A unit to measure the speed at which data bits can be transmitted or received. Bps differs from
baud when more than one bit is represented by a single cycle of the carrier.
Bridges: 1. A functional unit that interconnects two local area networks that use the same logical link protocol but may use
different medium access control protocols. 2. A functional unit that interconnects multiple LANs (locally or remotely) that use
the same logical link control protocol but that can use different medium access control protocols. A bridge forwards a frame
to another bridge based on the medium access control (MAC) address. 3. In the connection of local loops, channels, or
rings, the equipment and techniques used to match circuits and to facilitate accurate data transmission.
Buffer: A temporary storage register or Random Access Memory (RAM) used in all aspects of data communications which
prevents data from being lost due to differences in transmission speed. Keyboards, serial ports, muxes and printers are a
few examples of the devices that contain buffers.
Bus: A common channel between hardware devices either internally between components in a computer, or externally
between stations in a communications network.
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