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MultiModem ZPX User Guide 35

Glossary

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 withdigital 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).

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, andtermination fordirect

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

bitscan be transmitted or received.Bpsdiffers 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.

Bus Enumeration: Detecting and identifying Universal Serial Bus

devices.

Byte: The unit of information a computer can handle at one

time. The most common understanding is that a byte consists of

8 binary digits (bits), because that’s what computers can handle.

A byte holds the equivalent of a single character (such as the

letter A).

Call Setup Time: The time to establish a circuit-switched call

between two points. Includes dialing, wait time, and CO/long

distance service movement time.

Capabilities: Those attributes of a Universal Serial Bus device

that are administerable by the host.

Carrier Group Alarm (CGA): A T1 service alarm generated by a

channel bank when an OOF condition occurs for a predefined

length of time (usually 300mS to 2.5 seconds). The CGA causes

the calls using a trunk to be dropped and for trunk conditioning

to be applied.

Carrier signal: An analog signal with known frequency, amplitude

and phase characteristics used as a transport facility for useful

information. By knowing the original characteristics, a receiver

can interpret any changes as modulations, and thereby recover

the information.

Glossary

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