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MULTI-TECH SYSTEMS TELECOMMUNICATIONS GLOSSARY
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A
MULTI-TECH SYSTEMS
TELECOMMUNICATIONS
GLOSSARY
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*Accessory -- A type of program that can be called up during the execution of
another program to perform a certain task such as renaming a file on a disk, or
copying a file from one disk to another. An accessory program can also be used
to substitute a function of a computer with a different function (such as
making the program think disk A is disk B) or to provide data security (by
"scrambling" the data a program is saving or reading so that it cannot be read
properly unless it's re-accessed through the accessory). This type of program
is also called a TSR (Terminate, but Stay Resident).
*Accoustic modem -- A modem equipped with cups (usually rubber or plastic) to
hold a standard telephone handset. Since this type of modem has to deal with
room noise in addition to line noise (plus the quality of the accoustic signal
sent and received by the telephone), accoustic modems usually operate no faster
than 300 bps.
*ACIA -- Asynchronous Communications Interface Adapter. A device used for
serial data communication.
*ACK -- A control character that indicates the preceding transmission block
has been received (ACKnowledged), and that the next transmission block can be
sent.
*Algorithm -- A set of operational steps that perform a particular calculation
and/or function.
*Alphameric -- The letters, digits and special characters that are in common
use (a.k.a. "alphanumeric"). Generally, this means the keys you see on your
keyboard.
*Alternate routing -- Use of a second, third or more communication paths to
reach a point.
*Analog signal -- The continuous wave or signal that is recognized as
analogous to an original sound or signal. Also, the technique employing such a
system. Standard telephone lines employ analog for most voice transmissions.
Digital (or "pulse") transmission techniques are more appropriate for data
transmission (cf. Digital signal).
*Analog loop test -- A diagnostic test in which a single modem transmits data
from a terminal through the modem's transmitter, then back to the modem's
receiver, then back to the terminal. The modem may or may not be connected to
a telephone line. The transmitter of a modem performing an analog loop in full
duplex over standard two-wire lines is forced into the opposite mode of the
receiver (i.e., originate mode or answer mode).
*ANSI -- American National Standards Institute, the organization that sets
guidelines for the computer industry and other fields. ANSI-capable
microcomputers are equipped to take advantage of an emerging graphics standard
for data transmission (i.e., ANSI is to graphics what ASCII is to text).
*Answering mode -- The designation of modem operation on dial-up lines
signifying that the modem is answering another modem that sent it an
originating signal. The second modem is said to be operating in the "answer
mode."
*Answer back -- The identifying code that is automatically transmitted by a
station when it receives a special request signal from another station.
*Application -- A program or series of programs used to perform a specific
task such as Word Processing, Data Management or Telecommunications.
*ASCII -- American Standard Code for Information Interchange, a list of 128
switch positions corresponding to standard symbols (letters, numbers), using a
code with eight levels (seven bits plus one parity bit), and allowing
practically every type of microcomputer to understand text data generated by
other microcomputers. Pronounced "AS-key."
*Assembly language -- a list of mnemonics corresponding to machine-level
language sets.
*Asynchronous transmission -- Or "Asynch." Data format used in 300 bps
modems, most 1200 bps modems, and a few modems operating as faster speeds. The
use of "start" and "stop" bits is employed in asynch to identify individual
elements of the transmission. Information that is not transmitted
asynchronously is transmitted synchronously (cf.).
*AT command set -- The recognized industry standard modem communications
protocol.
*Attenuation -- A measurement in decibels of the decrease in current, voltage
or power of a signal traveling from one point to another.
*Autodial/Autoanswer unit -- A device that automatically dials telephone
numbers that are either entered into a "smart" telephone, or into a computer
file. Better modems are equipped with autodial/autoanswer, which can also work
with communications software to store telephone numbers, then dial any of them
at the touch of a single key.
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MULTI-TECH SYSTEMS
TELECOMMUNICATIONS
GLOSSARY
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*Bandwidth -- The distance between the highest and lowest frequencies of a
transmission band, as measured in Hertz.
*Bank -- The unit of memory that a microprocessor can address or "talk" to.
The size of the bank varies with each microprocessor.
*Batch processing -- A sequential processing method whereby several or many
similar applications are grouped and queued for processing.
*Baud -- A unit for measuring data transmission speed. The measurement
compares rate of signaling elements per second (i.e., the number of times the
communications line changes states each second). Often used interchangeably
with Bits Per Second (bps), the true baud rate is usually 1/2 the bits per
second in faster data transmissions. Typical data transmission speeds are 300
bps, 1200 bps, 2400 bps, 4800 bps, 9600 bps, and 19,200 bps. Data transmission
at speeds greater than 2400 bps over normal telephone lines require modems that
are able to transmit on more than one carrier frequency.
*Baudot code -- The five-bit binary code used in telegraphy. Its character
set is made up of 53 characters. Used when communicating with Telex, TWX and
other telegraphy-based machines.
*BBS -- Bulletin Board System. A computer, modem(s) and telephone line(s) set
up to let computer users call and post messages to be read by other users, and
to read messages posted by other users. The name refers to the sort of
bulletin board typically at supermarkets and other areas of high pedestrian
traffic, which is used to exchange information on goods or services that are
wanted or for sale.
*Bell-compatible -- A term signifying a device or circuit with audio tones
that meet Bell Telephone standards, or that otherwise meets generally accepted
network standards. Bell-compatible designations include Bell 103 (for 300 bps
modems; allows the use of four tones for full length operation on a single
channel, a.k.a. "Bell 113) and Bell 212A (for 1200 bps modems operating at full
duplex).
*Benchmark -- A program designed to test the performance of a processor in a
given application.
*Bit -- Acronym for Binary digIT, the smallest unit of information in a binary
system of notation. In eight-bit computers, eight bits make up a byte. Data
bits are used in combination to form bytes that represent characters. Framing
bits are used for parity. Transmission bits for synchronization.
*Bit error rate test -- A common method of measuring a modem's performance
(a.k.a. "BERT"). A good modem should make no more than one bit error every
100,000 bits.
*Bootstrap -- An initialization program used to start the operation of a
computer.
*bps -- Bits Per Second. A measurement of data transmission speed. Typical
transmission speeds are 300 bps, 1200 bps, 2400 bps, 4800 bps, 9600 bps and
19,200 bps (cf. Baud).
*BTAM -- Basic Telecommunications Access Method. The software protocol that
provides the macro instructions to control the transfer of data between main
storage and local or remote terminals.
*Buffer -- A temporary storage device that acts as a "holding tank" of
information. Buffers are usually used to capture incoming data (which is later
written to disk or some other storage device), or to otherwise compensate for a
varied rate of data flow, and can compensate for a change of characteristics
(voltage, speed, etc.) between two devices. Buffers can be in the software or
hardware.
*Bug -- An error in a piece of hardware or software.
*Byte -- Enough information to describe one letter, number, or other
character. Bits equal the same in all computers (a 1 or 0), bytes equal
different amounts of information in different computers.
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MULTI-TECH SYSTEMS
TELECOMMUNICATIONS
GLOSSARY
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*Carrier -- The base-level signal on which data is sent. A carrier signal
contains no information until it is altered through Frequency Modulation (FM),
Amplitude Modulation (AM) or some other method of encoding the transmitted
data.
*Carrier system -- A system that allows two or more channels to be split from
a single path. Different portions are assigned to different channels, which
are modulated on different carrier frequencies, sent to remote terminals, then
demodulated.
*CBBS -- Computer Bulletin Board System. The program written by Ward
Christensen and Randy Suess that pioneered the public computer
telecommunications revolution.
*CCITT -- Consultive Committee International Telephone and Telegraph (Comite
Consultatif International Telegraphique et Telephonique), an European advisory
committee set up by the United Nations to recommend worldwide standards of
transmission within the International Telecommunications Union (ITU).
*CD-ROM -- Compact Disc Read Only Memory. A means of storing data on a laser-
encrypted CD.
*Central office -- The facility of a telephone company that houses switching
equipment serving a specific geographic area.
*Channel -- A transmission path, usually unidirectional, through which data
travels.
*Character -- A single symbol (typically an alphabet letter or numerical
digit).
*Character length -- The number of data bits that make up a character. Seven
data bits are required to transmit each character in ASCII, giving each a
character length of seven. (An eighth bit is used to establish parity.)
*Character string -- A group of characters (letters or numbers) used to
represent a concept or value. Character strings in Basic typically begin with
CHR$. Character strings used in search functions are made up of the text to
which the search is to be keyed.
*Checksum -- A character residing at the end of a data block that corresponds
to the binary sum of all the characters in the block, used for error checking.
*Circuit -- The wiring or other means of connecting two points for
communication of one type or another.
*CICS -- Customer Information Control System. The interface that lets
terminals interact with a data base in a central processor.
*Clock -- A device used to generate time intervals marked by pulses that are
used for recording time and interacting with time-sensitive applications.
*Coaxial cable -- A transmission line consisting of an outer conductor and a
concentric inner conductor, separated from each other by insulating material
(a.k.a. "coax"). Coaxial cable is especially useful in data communications as
it possesses a predictable characteristic impedence.
*Command -- An instruction to a computer.
*Common carrier -- A company that furnishes communications services to the
general public. Common carriers are government-regulated firms that furnish
public communications facilities, such as telephone or telegraph companies.
*Communications settings -- The duplex, speed, parity, character length, error
correction and other variables that must match in order for two devices to
communicate (a.k.a. "protocols").
*Communications software -- The software used to select communications
settings, send data, and receive data (usually over telephone lines) (a.k.a.
"terminal program").
*Compandor -- Acronym for COMpressor/esPANDOR. A device used to compress the
volume range of a telephone circuit at one point and expand it later at a
second point. Used to improve signal-to-noise ratio.
*Conditioned lines -- Leased lines enhanced to function effectively for high
speed data transmission. Degrees of conditioning are expressed (progressively)
as C2, C3, C4, D1 and D2. Also applies to any type of circuit that is
specifically designed to meet the performance standards of a given device.
*Connect time -- The time, usually measured hours:minutes:seconds, spent
connected to a BBS or other information utility.
*Contention -- A line control system that pits individual terminals against
one another for transmission channel access. Terminals that request to
transmit are allowed to do so if an authorized channel is free. Other wise,
they form a queue of contention requests, and will be served in turn when a
channel becomes available.
*Control character -- A character that indicates a special signal (such as a
line feed or flow stop).
*CPU -- Central Processing Unit. The computer component that enterprets and
executes instructions. Also called the mainframe, although that term has taken
on a slightly different connotation in recent years.
*Crash -- A condition in which a computer will no longer accept commands from
the program or keyboard. The computer can be in programed loop (see Bug) or it
can be "locked up" trying to perform a function that is not possible. A
"hardware crash" is when a component within the computer fails. A "disk crash"
is when a floppy disk becomes unreadable by the computer. A disk crash can
cause the rest of the computer to crash as it tries over and over to access the
disk (although technically speaking, this isn't a crash, but a lock-up). The
term describes tha action of a floating disk head physically crashing into the
disk surface, thereby misreading or destroying the disk.
error correction during theChecking (an advanced form of Checksum). A method of
transmission of data blocks where a number is sent corresponding to the number
of bits in the block.
*Crossover cable -- A cable that connects the serial ports of two computers
(a.k.a. "null modem cable").
*CRT -- Cathode Ray Tube. A television picture tube or other device using an
electronic vacuum tube to display images.
*CUSIP -- Commission on Uniform Securities Identification Procedures. The
abbreviation that refers to a specific stock on the stock exchange board.
*Cursor -- The symbol used as a marker on a CRT display unit, showing where
the next character will be displayed.
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TELECOMMUNICATIONS
GLOSSARY
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*DDD -- Direct Distance Dialing, the standard public telephone lines (a.k.a.
"switched network," "dial-up network").
*Daisy chain -- An electrical wiring scheme that passes signals through logic
in every module to which the signals go.
*Data -- Any representation of information to which meaning can be assigned.
"Data" is actually the plural of "datum" (i.e., a single piece of information),
although it is commonly refered to in the singular.
*Data acquisition -- The gathering and categorizing of information that is to
be processed.
*Data base -- A large collection of data files organized for easy access.
Access to a data base may be limited to certain specific users and/or
application programs.
*Data communications -- Moving data from one point to another via an
electronic signal.
*Data processing -- A means of arranging and interpreting information through
the execution of systematic computational analyses of its values (a.k.a.
"information processing").
*Data processing system -- The computer components that work together to
analyze and act upon information.
*Data set -- A device that performs the tasks necessary to interface
communications facilities, terminals, computers, etc. More or less synonymous
with "modem."
*Data sink -- The computer component(s) that accept data transmitted to it.
*Data source -- The computer component(s) that provide data signals to be
transmitted.
*Data stream -- In a communications system, the flow of data, or its path.
*DB-25 connector. The standard RS-232C plug (25 pin connectors in two rows,
13 on top and 12 on bottom).
*dBm -- Decibel. A unit of power that can be equated to volume. Decibels are
measured on a logrhythmic scale based on 1 milliwatt (equal to zero dBm).
*DDS -- Data-Phone Digital Service. Private-line interstate service for
digital data communications. Trademark of AT&T.
*Debouncing -- Removing the intermediate noise states from a mechanical
switch.
*Dedicated line -- A telephone or telegraph line that is reserved for the
exclusive use of one customer to interconnect computers and/or terminals
(a.k.a. "leased line"). The line uses a port on the host computer, and is
always available as long as the computer is operating (on).
*Delay distortion -- The relative time it takes signals of different
frequencies to pass through a telephone line.
*Demodulation -- The DEM part of a MODEM, by which a modulated carrier wave is
decoded to retrieve data. This process is necessary to send data over most
telephone lines.
*Diagnostics -- Tests to check for and locate malfunctions or errors in
communications equipment, lines or channels.
*Dial-up -- The use of a dial or pushbotton telephone to initiate a station-
to-station call. Also, a port on a host computer that is activated only when
the computer detects a carrier (i.e., when it is called).
*Dial-up network -- The standard public telephone lines (a.k.a. "DDD,"
"switched network").
*Digital loop test -- A diagnostic test, involving two modems, in which Modem
A transmits data over a telephone line to Modem B, which loops the received
data to its transmitter on the digital side, then retransmits it to Modem A,
which checks it for errors.
*Digital signal -- A signal encoded in binary values of 0 and 1 (cf. Analog
signal).
*Disk drive -- A device for recording data magnetically on flat rotating
disks.
*Distortion -- Any undesired change in the waveform of a signal, or the
consequence of such a change. Amplitude vs. frequency distortion is the result
of non-uniform gain or attenuation with respect to a given frequency. Delay
vs. frequency distortion is the result of different transmit times of
frequencies within a given bandwidth and under predetermined conditions. Non-
linear distortion results from a variation in the normal linear relationship of
input and output signals.
*Distributed processing -- A system in which the individual remote terminals
of an organization are equipped to process data independent of the
organization's primary (and usually larger) computer.
*Download -- Transfering data from a remote computer to the one you're using,
especially via telephone modem, and saving it for future use. Software or text
files can be downloaded (cf. Upload). (To remember the difference between
downloading and uploading, imagine you are helping a friend move. As you stand
on the ground, you hand things up to your friend on the truck, i.e., you
upload. When you arrive at your friend's new home, he hands things down to
you, i.e., you download.)
*Drop -- The part of a telephone distribution network that runs to a customer
terminal (e.g., from pole to house, buried cable to business office, etc.).
*Duplex -- A measurement of the manner in which data is transmitted and
received. Full duplex employs simultaneous data transmission and receiption.
Half duplex transmission and reception occurs in alternate intervals. (It's
easy to identify a duplex problem. In full duplex, the characters you see on
your screen are actually sent by the other computer. In half duplex, they come
from your own computer. If you have the settings mixed up, you will see two
characters for every one you type when you are in half duplex and the other
computer is in full duplex, or you will not see any characters if you are in
full duplex and the other computer is in half duplex.) Also known as "Echo
Back" or simply "Echo" in some terminal programs.
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TELECOMMUNICATIONS
GLOSSARY
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*EBCDIC -- Extended Binary Coded Decimal Interchange Code. A nine-level code
(eight bits + parity bit) used primarily in IBM systems. (IBM also uses an
eight-bit version of the USASCII code, USASCII-8.) Used primarily in IBM
Mainframe systems, although there are several telecommunications software
products that will support EBCDIC on a PC, and several products that will
convert EBCDIC into ASCII.
*Echo -- The process of sending an acknowledging character or signal back to a
computer.
*Echo suppressor -- A line device that prevents echos.
*EIA-RS232C -- Sometimes called the "serial port." The computer interface
used by virtually all modems. Current loop, TTL and IEEE (sometimes called the
"parallel port") are other ports occasionally used to transmit data through or
in coordination with modems.
*Emulate -- To simulate the actions of a device or system in real time.
*EOF -- End Of File. The character that signifies this.
*EOT -- End Of Transmission. The character that signifies this.
*Equalization -- The process and result of conditioning lines (e.g.,
eliminating noise, limiting frequency response, etc.). Used as a noun or verb.
*Error burst -- The event and result of a sudden increase in errors over a
short period.
*Error-correcting code -- A computer data transmission code that allows one or
more bits of data to be in error without resulting in the loss of any
information.
*Error control -- The arrangement by which transmitted data is checked for
errors, then corrected at either the receiving site or through a request for
retransmission of data blocks containing errors.
*Error detecting and feedback system -- Any error detecting system that is
designed to request a retransmission of data blocks containing errors (a.k.a.
"decision feedback system," "requests repeat system," "ARQ system").
*Error detecting system -- A system that notes and/or deletes errors in the
transmissions it receives.
*Error rate -- The amount of data received with errors, divided by the total
amount data transmitted.
*Eye pattern -- A visual pattern on an oscilloscope that resembles a human
eye.
Used as a measurement of an equalization line signal.
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F
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TELECOMMUNICATIONS
GLOSSARY
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*Facsimile -- (Also called FAX) The transmission of photographs, maps,
diagrams, and other graphic data by communications channels, or the image that
is transmitted, or the device used to transmit the image. A facsimile
(machine) transmits a series of encoded impulses, which are reconstructed and
printed at the remote location.
*FAX -- Facsimile.
*FCC-Certified -- Equipment that has been manufactured to meet the standards
of the Federal Communications Commission, particularly the criteria put forth
in Part 68 of the FCC Rules and Regulations. FCC-Certified devices are
equipped with internal circuitry to handle DAA (Data Access Arrangement), and
can therefore be connected directly to a phone network.
*Feedback -- The response to instructions or queries. Used for equipment or
software control or self-correction. Also, re-introducing the output of a
signal into the device producing the signal, and the result thereof.
*Firmware -- Microcomputer programs stored in ROM, e.g., a processor-internal
bootstrap program.
*Flag -- A status signal in hardware or a bit of software-induced memory that
indicates a status until read and/or reset by the user or communications
device.
*Flip-flop -- A circuit or device to used store a single bit of information,
and which may be set in one of two postions (one or zero, on or off, etc.).
*Floppy disk -- A square, flexible disk used to store magnetically recorded
data. Usually measures 8" square, 5-1/4" square, or 3-1/2" square (although
the smaller format disks are encased in hard plastic, making them neither
floppy or flexible.
*Flow control -- The method of controlling the flow of characters onto a
screen, using the X-ON/X-OFF commands (control-Q/control-S).
*Four-wire circuit -- A communications path with four wires, each used for
unidirectional communication (two for send and two for receive).
*Framing bits -- The bits that "frame" the data in each character transmitted
using asynchronous communication. They are: start, parity and stop. The
typical microcomputer-based BBS operates at eight bits, no parity and one stop
bit.
*FSK -- Frequency Shift Keying. A method of data transmission in which a
carrier signal's frequency shifts back and forth between two possible states
(1/0, off/on, yes/no, etc.). This is the most common form of FM transmission.
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TELECOMMUNICATIONS
GLOSSARY
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*Glitch -- An unwanted transient noise pulse or burst of pulses, usually of
very short duration and high amplitude. Any unexplained problem, malfunction,
distortion or, generally, event or phenomenon that causes a thing to go
kablooey.
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TELECOMMUNICATIONS
GLOSSARY
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*Handshaking -- The exchange of predetermined signals that two computers
perform to establish connection.
*Hard copy -- The output of a printer that is registered on paper (as opposed
to a visual display on a CRT, or an audio signal, or the data stored on a
floppy disk).
*Hard Disk -- A standard, nonflexible, usually self-contained disk that can
store large quantities of data.
*Hardware -- The electrical components and equipment that makes up a computer.
*Hard-wired -- Linked directly without the use of accoustic couplers or
broadcast signalings. Hard-wired (or "direct connect") modems plug directly
into standard RJ-11 phone jacks. Also, a condition describing anything
connected by wires and screws, as opposed to plugs and outlets.
*Hayes-compatible -- A term signifying a modem that recognizes the "AT command
set." Refers to the Hayes(TM) modem, which pioneered the AT command set.
*Hertz -- A measure of frequency. One Hertz is equal to one cycle per second
(cps).
*High codes -- ASCII code numbers above 127 (a.k.a. extended character set).
High codes are used to signify any of a number of unusual characters, and are
generally non-standardized.
*High-level language -- The computer language that comes closest to human
language when compared against low-level language sets such as machine code.
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I
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TELECOMMUNICATIONS
GLOSSARY
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*IC -- Integrated Circuit. A microchip.
*ICA -- Integrated Communications Adapter. A device used to interconnect a
processing unit to multiple lines.
*IEEE -- Institute of Electrical and Electronics Engineers. The IEEE-448 port
was created by the Institute to standardize signals used in parallel
transmission. Because of this, it is sometimes called the parallel port. It
is the parallel equivalent of the RS-232C (serial) port. Many microcomputers
use this port for communication with printers, but some micros (Commodore, VIC,
PET and CBM) use it for telecommunications. The IEEE also establishes
standards for other things such as programming languages (i.e. COBAL, PASCAL,
and C), display characters (i.e. ANSI), and some computer circuitry.
*IMS -- Information Management System. Software for IBM that lets special
applications run on remote terminal systems. Uses BTAM.
*Information bit -- A data character bit. A bit that helps compile
characters, rather than indicating start, stop, parity or other transmission
data (as with transmission bits and framing bits).
*Intelligent terminal -- A terminal capable of limited processing functions
(a.k.a. "smart terminal"). Usually used at a remote site in coordination with
a central site computer.
*Interface -- The place where two devices or systems connect. Standard
interfaces are the RS-232C (serial) and IEEE-448 (parallel). Loosely used as
synonymous with "port."
*ISDN -- Integrated Services Digital Network. An all-digital communications
transport system that uses dial-up lines, split into several channels, to carry
audio and video data in a variety of formats.
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GLOSSARY
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*K -- Kilobyte (1024 bytes, roughly equated with 1000 bytes, of information).
*Keypress -- Usually refers to the act of pressing a certain key on the
keyboard that activates a certain funtion. Sometimes this requires the pressing
of two or more keys at the same time such as the Alternate key and some other
key (usually abreviated as ALT-<key to be pressed>) or the Control key and
another key (usually abreivated as CTRL-<key to be pressed> or ^<key to be
pressed>). Example: CTRL-Q (or ^Q) refers to holding the Control key and
pressing the Q key. ALT-Q means to simultaneously hold down the Alternate key
and the Q key.
*Keyword -- A character string used as a reference in a data search function.
A search for information on semi-trailer trucks, for example, could use "semi"
or "semi-trailer" or "truck" as keywords.
*KSR -- Keyboard Send/Receive. A device for sending and receive data (e.g., a
terminal with a keyboard).
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GLOSSARY
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*LAN -- Local Area Network. A device used to link several processors without
the use of telephone lines. Also, the design and arrangement of such a
network.
*Laser -- Light Amplification by Stimulated Emission of Radiation. A
controlled, narrow beam of light. Used to read compact discs and other media,
carry signals over fiber optics, assist in micro surgery, and in many other
applications.
*Leased lines -- Transmission lines running from one point to another point,
or several points, that effectively allow connected modems to remain on-line at
all times (a.k.a. "dedicated lines," "3002 lines"). These lines are
independent of the standard dial-up network lines.
*Line feed -- A control character that tells the printer or screen to move to
the next line. Some software automatically adds line feeds after carriage
returns, others do not.
*Line hit -- Interference in an electrical circuit as a result of spurious
signals.
*Line speed -- The highest speed, measured in bauds or bps, at which signals
may be transmitted over a channel.
*Local loop -- The wiring between a local telephone company exchange and the
telephone equipment at a site served by it (a.k.a. "the last mile").
*LRC -- Longitudinal redundancy check. An error control system that checks
each character transmitted in a block check following preset rules (e.g.,
parity-checking all characters in a block).
*Loop (defination 1) -- See Loop (defination 2).
*Loop (defination 2) -- See Loop (defination 1).
*Loopback tests -- Tests that measure signals looped from a test center
through a modem and back to the test center.
*Loop system -- Hardware arranged for use in a closed series transmission
circuit with a limited number of terminal points.
*Low-level language -- Computer language at the machine level, assembly level,
or other low level as compared to human speech or high-level computer language.
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*Machine language -- The lowest level of communication with a computer.
Machine level language can be executed directly by the CPU. Other programs
require a interpreter or must be compiled into machine language before the
computer can execute them.
*Macro -- A sequence of instructions that is given a separate name, used
often, and implemented by a macro assembler whenever the name is submitted.
Also, a macro routine (e.g., the sequence of characters that is automatically
given by a terminal program when the user logs onto a given BBS or other data
communications system).
*Macro assembler -- An assembler capable of handling macro routines.
*Mainframe -- A large computer (as opposed to a microcomputer, minicomputer or
supercomputer). This term also sometimes refers to any computer's Central
Processing Unit (CPU), and is sometimes used interchangeably with
"minicomputer."
*Mark -- Binary one, i.e., a signal (one, plus, closed, on, etc.) (cf. Space).
*Maser -- Microwave Amplification by Stimulated Emission of Radiation. A
device capable of amplifying extremely weak signals by amplifying microwaves to
generate radiation. Masers introduce very little noise, and are used in
satellite-to-ground communications.
*Medium -- The method, and type of method, used to store information (e.g.,
floppy disk, magnetic tape, CD-ROM, etc.).
*Meg -- Megabyte (one million bits of information).
*Menu -- A table of contents listing the options, programs or parts of
programs that can be accessed at any given time.
*Message format -- The way a message must be entered to be correctly accepted
by a communications system, as regarding the message's destination, text, EOF,
etc.
*Message numbering -- Sequentially numbering messages for later reference.
*Message switching -- A computer-controlled communications system that
receives a message, analyzes the destination, stores the message (if necessary)
until the proper outgoing line is available, and retransmits it toward its
destination automatically.
*Microcomputer -- A computer based on microprocessor technology. "Micros" are
low in cost, somewhat limited in speed and (less so) in storage than
minicomputers or mainframes, and are generally called "personal computers."
*Microprocessor -- A complete processor including arighmetic logic and control
logic, all on one or more IC chip(s).
*Microwave -- Electromagnetic radiation beyond 890 megaHertz. Also, a radio
system or facility that operates on a line-of-sight basis (thus requiring
repeater stations every 18 to 30 miles depending on the contour of the earth),
and generally capable of carrying broad bandwidths and large quantities of
circuits.
*Minicomputer -- A medium-sized computer that is larger than a microcomputer,
not as large as a supercomputer, and usually used in business or education.
The term is often used interchangeably with mainframe (but not with CPU). As
the capabilities of microcomputers increase, this type of computer is becoming
less practical, although it is not yet obsolete.
*MNP -- Microcom Networking Protocol(TM). The recognized industry standard
for error correction and data compression. Developed by Microcom, Inc.
*Mode -- The manner in which a system operates or is set to operate (i.e.,
Local, Remote, Host, etc.).
*Modem -- An acronym for MOdulator/DEModulator. This generic term for refers
to a device that can convert binary digital data into audio tones suitable for
transmission over standard telephone lines, and re-convert audio tones back
into binary digital information.
*Modem sharing -- Using one modem to serve the needs of several devices.
*Modulation -- The means by which digital signals are encoded into analog wave
forms, then transmitted. Modulatin techniques include:
..Amplitude Modulation (AM) and Quadrature Amplitude Modulation (QAM) --
modulation varying the amplitude of the carrier, usually found in 9600 bps
modems and VA3400 modems.
..Differential Modulation -- modulation varying a significiant condition for
any given signal element as related to the signal element immediately preceding
it.re-
..Frequency Modulation (FM) -- modulation varying the instananeous frequency
of a sine wave carrier.
..Frequency Shift Keyed (FSK) -- a two-level FM technique employing one level
for binary "one" (mark) and the other for binary "zero" (space). Found in 103
and 202 modems.
..Phase Modulation (PM) -- modulation varying the angle relative to the
unmodulated carrier angle as related to the value of the amplitude of the
modulating signal.
..Pulse Amplitude Modulation -- modulation varying the amplitude of the pulse
carrier as related to successive samples of the modulating signal.
..Pulse Code Modulation -- modulation varying a signal's quantity and/or type
of pulses and spaces as related to those values in a a sample signal.
*Monitor -- A program that performs communication between a computer and the
console terminal, and handles similar system loading and execution commands.
Also, a program that "watches" and/or records what happens in a computer's
memory (used to improve efficiency or for troubleshooting). Also, a video
display device.
*Multiplex -- To transmit and receive multiple messages on a single channel,
usually involving operation at high speeds.
*Multiplexor -- A device for multiplexing (a.k.a. "mux"). Several distinct
multiplexing techniques are in common use:
..Frequency Division Multiplexing (FDM) -- Assigning different frequency
bandwidths to different channels. This is the earliest form of multiplexing.
..Time Division Multiplexing (TDM) -- Assigning different slices of time to
different channels.
..Statistical Multiplexing (using a "stat mux") -- Using microprocessors for
data control, a statistical time division process is employed to efficiently
convert asynchronous characters into synchronous data blocks. The data blocks
are then sent to another mux. Each of the data blocks includes instructions
for re-assembly at the remote site. Stat muxes are the most common
multiplexers in use today.
*Multiplexing -- Channeling two or more signals to one source, or sharing a
system resource between users.
*Multipoint circuit -- A circuit through which three or more stations share
information.
*Multi-tasking -- A means of operating at several levels simultaneously, e.g.
running several distinct programs at once. Technically, the programs Timeshare
the CPU to perform the illusion of having two or more programs running at the
same time. It should be noted that when running more the one program at the
same time, the overall speeds of the programs will decrease. The more programs
that are run, the slower the speed of the programs.
*MUMPS -- Multi-User Multi-Processor System. An operating system that allows
several computers share information efficiently.
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*NAK -- A control character used to signify that a message was not received
(Negative AcKnowledgement).
*Network -- A system of points interconnected by communication channels such
as computers, terminals, microchips, etc.. Networks can encompas an office, a
building, or a large region. Public telephone lines are sometimes refered to
as the "switched network."
*Network management system -- The overall setup of a system used to monitor,
control and manage a data communications network. Includes CRT's, printers,
testing equipment and circuitry, etc., usually all located in a central unit
with an operator control interface.
*Noise -- An unwanted electrical (or audio) disturbance in a transmission or
reception.
*Noise measurement units -- The terms that measure weighted and unweighted
circuit noise (expressed in decibel rated noise, or dBrn).
*Noise weighting -- A way of measuring the noise of a system as related to the
operating characteristics of a particular class of telephone subset.
*Null modem cable -- A cable that connects the serial ports of two computers
(a.k.a. "crossover cable"). A null modem cable acts as if it is interpreting
modem signals sent to and from computers that are set to communicate via
modems, but not connected to modems.
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*Off-line -- The state of operation in which a system or device is not
directly controled by a primary CPU, as in a microprocessing terminal operating
independent of a mainframe to which it is connected.
*On-line -- The state of operation in which a system or device is controlled
by a primary CPU, as in a terminal interfacing with a mainframe (a.k.a.
"online").
*On-line system -- A direct-connect setup whereby information is entered
and/or received at remote locations.
*Operating system -- The software that performs simple housekeeping functions
such as the translation of higher-level language programs, communication
between keyboard and CPU, etc. Some operating systems are: PC-DOS, MS-DOS,
Apple-OS and CP/M (all trademarked names).
*Operating time -- The time it takes to dial, connect and carry out an
exchange with a remote system (cf. "Response time").
*Originate mode -- The designation of modem operation on dial-up lines
signifying that the modem is sending the originating (first) signal and
expecting to receive an appropriate return signal from another modem in the
answering mode of operation.
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*Packet-switching networks -- Electronic networks that segment data into
"packets," give them addresses, and allow you to send them to remote locations
via a local phone number. Telenet, Tymnet and Uninet are packet-switching
networks in common use.
*Parallel processing -- A superior method of running two or more programs at
the same time. Separate CPUs are 'hooked' together, yet each runs it's own
programs.
*Parallel transmission -- An uncommon data transmission format employing a
method whereby transmission bits are sent all at once (instead of
sequentially).
*Parity -- A form of error checking. This system tests data to ensure that
the number of ones or zeros in an array of binary digits is consistent. When
odd parity is used, the system compares the 1s and 0s transmitted, and adds an
eighth bit if that's necessary to make it odd, or leaves it odd if that's the
way it's received. Even parity works in like manner. No parity means the
eighth bit is still transmitted, but ignored at both ends. Parity checking
detects characters, blocks, and other bit groupings containing single errors.
*Patch panel -- A circuit board used to patch cables (usually temporarily) in
such a way as to modify or reconfigure a system.
*Peripheral -- Any device that attaches to a computer that is not, strictly
speaking, essential to its functionability. A keyboard is not a peripheral, a
printer is, as is a modem, CRT, disk drive, etc.
*Phase jitter -- Fluctuation in the length of a signal, and the distortion
this produces.
*Polar keying -- A telegraph signaling system involving two states
(mark/space) represented by the two directions in which current can flow.
*Polling -- A way of controlling who goes first. This centrally-administered
method of directing traffic is an alternative to contention, as it means no
single terminal is kept waiting for an inordinate amount of time. The
processor repeatedly cycles through the list of users on line at any given time
to see if any data is waiting to be sent. If so, the request is processed.
Some BBS's and other on-line data systems will exhibit delays due to polling
cycles when a large number of users are accessing them simultaneously.
*Port -- The interface through which a computer passes information. The place
where you insert the plug of a cable.
*Protocols -- The duplex, speed, parity, character length, error correction
and other variables that must match in order for two devices to communicate
(a.k.a. "communications settings").
*Pulse -- A sudden raise or drop in voltage or amplitude used to carry digital
information over a wire or other channel. Also, the sudden change in a circuit
that produces this result (e.g., reversed polarization).
*Pulse dialing -- A system of dialing whereby one sudden drop of voltage (such
as that produced by hanging up the phone for an instant) is equal to the number
one, two pulses are equal to two, etc. Used by rotary dial telephones (cf.
Touch-Tone).
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*QTAM -- Qued Telecommunications Access Method. Software protocol providing
BTAM's capabilities, with the additional ability to queue messages on direct-
access storage devices. Used in data collection, message switching, other
teleprocessing tasks.
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*RAM -- Random Access Memory. A storage system allowing data to be read,
written and erased. Analogous to a cassette tape of music (cf. ROM).
*RAM drive -- A section of Random Access Memory set up to act like a disk
drive (a.k.a. "RAMdisk"). These 'drives' are very fast and are most commonly
used to speed up the uploading and downloading of information. They are,
however, very volatile since a crash (either hardware or software) can cause
the loss of all data on the RAM drive. Turning off the computer also erases
the RAM drive.
*Random access -- The ability to move directly to any location in a memory or
on a disk drive without traveling through all points in between (as opposed to
"sequential access").
*RCPM -- Remote CP/M system. A BBS running on a computer with a CP/M
operating system.
*Real time -- Time as it passes in normal human experience. A voice
conversation on the telephone takes place in real time. A conversation via the
U.S. Mail does not.
*Redundancy -- Unnecessary information in the sense that it is repeated or can
be eliminated without detrement to the essential message, e.g., superfluous
control characters. Also, a computer or system employing backup components, or
the individual components, to insure uninterrupted service.
*Remote Digital Loop -- A digital loop (cf.) configuration in which one modem
can signal the other to place itself in the digital loop mode.
*Remote station -- A workstation or processor not directly wired to a primary
CPU, e.g., a terminal on a network. Usually located at some considerable
distance from the primary CPU, and using electronic communication for access.
*Repeater -- A device that automatically repeats signals, and usually
involving amplification (analog), recreation (digital) and/or other measures to
enhance comprehension of the signals.
*Response time -- The time it takes to provide information or otherwise
respond to a request (usually including the time to transmit, process and
receive the response to the request) (cf. "Operating time").
*Reverse channel -- A secondary channel often found in older modems Typical
reverse channels operate at 5 bps, 75 bps or 150 bps, and are used for
controlling line turnaround.
*Ring-back -- A technique used by some BBS sysops that saves the cost of an
extra telephone line. To use a ring-back system, callers dial the number, let
it ring once, hang up, then redial. After redialing, the ring-back BBS
computer will answer the telephone. Also, a telephone company term that refers
to an operator function of ringing an originating telephone, regardless of
whether the originating telephone is on hook.
*RJ-11 -- The standard telephone outlet or plug.
*RJE -- Remote Job Entry. Using remote terminals to enter applications
programs data and/or instructions.
*ROM -- Read Only Memory. A storage system from which data can be read, but
on which data can't be written. Analogous to a standard lp record (cf. RAM).
*Routing indicator -- The data that tells a message where it should go, e.g.,
a code, address, character string, etc.
*RS-232C -- The standard of signals and voltages (and the port) established by
the Electronics Industry Association to codify the transmission data protocol
used to connect a computer and a modem (a.k.a. "EIA-RS-232C").
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*Screen -- The part of a CRT that displays information. Different screens can
appear on a CRT at once to show data entry, give help to the user, display
files in storage, etc.
*Scroll -- The line-by-line movement of text across the computer screen
(usually bottom to top) or of other incoming data. Also used as a verb.
*SDLC -- Synchronous DataLink Control. A system used with IBM network
architecture (SNA) communications lines. Offers the initiation, control,
checking and termination of information exchange in full duplex.
*Search -- To run a program or routine that compares the data in a file to a
specified character string (cf. Keyword).
*Selective calling -- The capability to specify the individual, distinct
stations that are to receive a message.
*Self test -- A diagnostic test in which a single modem generates a data
pattern internally, then transmits the message to its own receiver, then checks
the data for errors.
*Serial card -- A circuit board installed in a computer to convert the
machine's parallel communications into serial communications. A serial port
comes as part of the serial card.
*Serial port -- The interface of a computer typically used to transmit
information to and from a modem. On most computers this is the RS-232C port.
*Serial transmission -- The most common format for transmitting data employing
a method whereby each bit of a character is sent sequentially on a single
circuit or channel.
*Short-haul modems -- Modems designed to operate over limited distances,
usually up to 25 miles (a.k.a. "limited distance modems"). Short haul modems
can operate efficiently with less filtering and other circuitry typically
needed for longer distance modems, allowing speeds of 19,200 bps and faster.
*Signal wave -- Unwanted disturbance imposed intentionally on a communications
line (as opposed to random "noise").
*Simplex -- Pertains to a communications system or device capable of data
transmission in one direction only.
*Software -- The instructions to a computer. Code that tells a computer what
to do and how to do it. Also used interchangeably with "software package."
*Software package -- A program or set of programs designed to perform a
function.
*Space -- Binary zero i.e., the absence of a signal (zero, minus, open, off,
etc.) (cf. Mark).
*Start element -- The beginning of certain specific types of serial
transmissions. Used for synchronization.
*Station -- The telephone set at a specific location (e.g., an office phone).
*Store and forward -- To receive and hold complete messages, which are then
forwarded as required.
*Supercomputer -- A very large computer designed to process massive amounts of
data in very short time frames, used primarily in research and scientific
industry. Cray and Control Data are two of the few companies that offer
supercomputer technology in their products.
*Supervisory control -- The characters or signals used to instigate action at
remote stations.
*Switched network -- The standard public telephone lines (a.k.a. "dial-up
network," DDD). Also, any telephone network employing a similar system.
*Synchronous transmission -- Or "bisynch" (for binary synchronous). Modems
operating at 9600 bps and faster typically use this form of data transmission.
Data is sent in continuous streams of bits, without the use of "stop" and
"start" bits to identify elements of the data package.
*Sysop -- System Operator. The person who maintains a BBS or other online
communications system. (Pronounced SIS-op).
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*Tail circuit -- A final circuit in a multidrop communications setup, or the
devices and/or lines that terminate a communications channel.
*TCAM -- TeleCommunications Access Method. A software protocol that is used
to construct programs for controlling messages between remote stations, or
between remote stations and applications programs, through the use of high-
level message control language.
*Teleprinter -- The equipment that turns communications signals into hard
copy; specifically, a self-contained unit that accomplishes this, such as a
teletypewriter.
*Teleprinter exchange service -- A method of connecting teleprinters through
common carriers (e.g., Telex, TWX, etc.).
*Teleprocessing -- Manipulating data via communications networks or terminals.
*Teletype -- A general term refering to a specific type of terminal used for
communications systems. Also, a trademark of the Teletype Corporation,
describing such equipment as trasmitters, tape punches, reperforators, page
printers and other units made for communications use.
*Telex -- Acronym for TELegraph EXchange. Special machines that act as
communications terminals on dedicated lines, capable of speeds up to only 50
baud, using the Baudot code, and generally useful to companies doing business
internationally.
*Terminal -- A peripheral device that can serve as an input device (data
reader), or an output device (printer) or both (CRT). Any device capable of
sending and/or receiving information over a communication channel. Any device
or place where information is entered or received in a communication network.
*Terminal mode -- A way of operating that causes a computer to act as a
terminal.
*Terminal program -- The software used to select communications settings, send
data, and receive data (usually over telephone lines) (a.k.a. "communications
software").
*Text -- The written part of a message (like the body of a letter), or any
data that isn't graphics, programming, protocol bits, etc.
*Throughput -- The information that is processed or sent and received in a
given period of time.
*Tie line -- A telephone service that links two or more points via a private
communication channel.
*Timesharing -- Splitting the resources of a computer or system in such a way
as to serve the purposes of more than one user at roughly, or apparently, the
same time.
*Toggle -- To switch from one option to a second and only choice within a
framework (e.g., toggle between black/white display and color display, toggle
between insert and overwrite, etc.). May be used as noun or verb.
*Touch-Tone -- A trademark of AT&T referring to the system of push-button
dialing (cf. Pulse dialing).
*Trellis coding -- A technique for coding data onto a telephone line that
reduces the harmful effects of data distortion through line noise. Used with
devices operating at speeds up to 28,000 bps.
*Trojan horse -- A program that appears to perform a certain task, or is
documented in such a way as to indicate a particular application, but which
really performs another, usually detrimental action. Trojan horses can, but do
not necessarily, contain viruses (cf.). A Trojan horse program can perform the
application for which it appears to be created (e.g., a spreadsheet program)
for a period of time, then perform destructive actions at a later time. Some
Trojan horse programs do not carry out the actual distruction of the data, but
act solely as a method of spreading a virus. They are named after history's
infamous Greek Trojan Horse that helped destroy the ancient city of Troy.
*Trunk -- The main, central and sometimes only circuit between two points that
are used for switching and/or distribution. Also, the facility that connects
various switching offices, or the facility that connects a telephone company
and a customer's switching equipment.
*TSO -- Timesharing Option. T type of interaction between terminals and the
system of which they are a part that uses conversational or request/response
methods of information exchange.
*Turnaround time -- The time required to reverse the direction of transmission
on a half-duplex circuit (a.k.a. "half-duplex turnaround time").
*TWX -- Western Union's teleprinter exchange service. It provides a direct
connection between subscribers, who communicate in real time. Similar to a
Telex, but operating at up to 110 baud.
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GLOSSARY
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*Unnattended operation -- The ability of a system to carry out tasks without
direct human supervision.
*Upload -- Transfering data from your a storage medium in computer (such as a
floppy disk or buffer) to a remote computer, especially via telephone modem.
Software or text files can be uploaded (cf. Download). (To remember the
difference between downloading and uploading, imagine you are helping a friend
move. As you stand on the ground, you hand things up to your friend on the
truck, i.e., you upload. When you arrive at your friend's new home, he hands
things down to you, i.e., you download.)
*USASCII -- USA Standard Code for Information Interchange. A seven bit +
parity code including information, graphic and control characters, used in the
exchange of information among some data processing systems.
*User-friendly -- A term describing a computer, peripheral or other electronic
system that is simple to operate. Caveat emptor.
*Utility -- A short program that performs a useful task, e.g., copy disks,
copy files, merge files, delete files, format disks, etc.
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*Virus -- A program of the TSR type (see Accessory) that is simular to a virus
in human terms; the program tries to hide itself from detection, creates copies
of itself onto other computers (usually via "infecting" a floppy disk) and
interupts normal funtions. Viruses are usually destructive programs and may
wait for certain conditions to be fulfilled (such as reaching a certain date or
the entry of a certain set of keypresses) before taking effect (cf. Trojan
horse).
*Voice grade channel -- A telephone circuit capable of effectively
transmitting speech or data within a frequency range of roughly 300 to 3000
Hertz.
*VTAM -- Virtual Telecommunications Access Method. An IBM System 370 protocol
that provides remote terminal users with access to applications programs. VTAM
also offers resource sharing (to reduce transmission costs within a network).
*VU -- Volume Unit. The power unit used to measure dBm in in terms of a sine
wave test tone (Zero VU = zero dBm).
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*WATS -- Wide Area Telephone Service. Originally, the circuitry and service
provided by telephone companies to customers wishing to be billed at a flat
monthly charge for long distance calls that are placed or taken by the
customers, as opposed to a per-call billing system. WATS is evolving into less
of a facility and more of a marketing tool. Some WATS services now incorporate
per-call billing.
*Wideband channel -- A channel with a bandwidth that is broader than a
standard voice-grade channel.
*Word -- A predefined field of bits that usually consists of two bytes.
Microcomputers typically have words of eight or sixteen bits.
*WPM -- Words Per Minute. The measure of words typed, printed, sent or
received by a terminal or operator.
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*X-ON/X-OFF -- The start and stop signs posted by two computers that are
communicating with each other. This "flow control" (cf.) method is used to
signal that a computer is ready to send or receive data. Most communications
software is equipped with X-ON/X-OFF. Most BBS's recognize it, allowing you to
activate X-ON (control-Q) or X-OFF (control-S) at your keyboard, to control the
flow of information across your screen.
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MULTI-TECH SYSTEMS, INC. (612) 631-3550 (voice) (612) 631-0922 (data)

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