Multi-Tech ISIHI-2S Specifikace stáhnout pdf (Strana 179)

MultiModem ISI Hybrid Series, ISIHI-2S/2U 179

Glossary

kermitAn asynchronous file transfer protocol noted for its

accuracy over noisy lines.

kernelThe core of an operating system that interacts

directly with the system hardware. While most operating

systems are based on the concept of a kernel, the term is

best recognized as a fundamental of the UNIX operating

system. Kernels have been expanded to include commonly

used utilities, but with the advent of the micro kernel, the

original modular design of UNIX is being revived.

kilobitOne thousand bits, a unit of measure for digital data

rates.

kilobyteOne thousand bytes. A unit of measure for digital

data rates. Not to be confused with K, which stands for z

bytes of storage space, either in memory or on disk. 1K of

disk space is actually 1024 bytes. 16K is 65,536 bytes, and

1M (meg) is 1,048,576 bytes.

LAM (line adapter module)The cabling that connects the

phone line to the PCMCIA modem card.

LAN cardAn IC Card that complies with the PCMCIA

Card Services Interface Specification, Release 2.0. LAN

cards can be connected to laptops or palmtop computers

which, in turn, can be interconnected to local LAN services.

leased lineA private, dedicated communications channel

that connects two locations. This connection lasts for the

duration of the subscription. Leased lines can be condi-

tioned to improve line quality over that of dial-up lines.

line conditioningAn additional cost option offered by the

telephone company for their leased, voice-grade lines. The

service provides a careful balance of line enhancements to

improve the frequency response and to reduce distortion.

LPTx (line printer)The parallel port interface on a PC. It

provides a 25-pin connector for parallel transfer of data and

printer controls, commonly used for parallel printers. A

maximum of four I/O addresses are set with DOS param-

eters LPT1, LPT2, LPT3 and LPT4.

LRC (longitudinal redundancy check)An error checking

method that generates a parity bit from the specified string

of bits on a longitudinal track. In a row and column format

such as on magnetic tape, LRC is often used with VRC,

which creates a parity bit for each character.

macroA series of keystrokes, commands, and/or menu

selections that have been recorded and assigned a key or

key combination. When those keys are pressed, the macro

is carried out from beginning to end.

magnetic diskA nonvolatile computer storage device that

uses one or more magnetic-coated disk platters that can be

recorded over again. Hard disks, minifloppies (5-1/4") and

microfloppies (3-1/2") are examples of magnetic disks.

mainframeA large, powerful computer used to centralize a

data processing environment. It has hundreds of gigabytes

of storage space. It uses a front end processor to connect

directly to the communications channels that interconnect

terminals and computers.

megabyteOne million bytes, when describing a data rate.

1M of disk space may actually mean 1,048,576 bytes.

mid-range computerA term coined by IBM, referring to

any of their Advanced Business Systems computers. This

product line was originally called their minicomputers, but

as the number of supported users approached mainframe

capabilities, the term mid-range caught on.

MI/MIC (mode indicate/mode indicate common interface)

A user definable feature that defines various combinations

of edge or level detection in originate or answer mode, with

the ring indicator (RI) pulse enabled or disabled.

mnemonicsA term assigned to a complex idea, value, or

list of information that is representative of that information.

Computer commands are almost entirely mnemonics.

Mnemonics are used as memory aids for people.

MNP (Microcom Networking Protocol)A family of

communications protocols from Microcom that have

become de facto standards for error correction and data

compression.

MNP Class 3 & 4The de facto error correction standard

from Microcom.

MNP Class 5The most widely used data compression

scheme before V.42biS. MNP5 offers 2-to-1 data compres-

sion.

MNP Class 7MNPs 3-to-1 data compression scheme.

MNP7 never became a de facto standard because of V.42bis

4-to-1 compression.

modemA communications device that enables a computer

to transmit information over a telephone line. It converts

the computers digital signals into analog signals to send

over a telephone line and converts them back to digital

signals at the receiving end. Modems can be internal and fit

into an expansion slot or external and connect to a serial

port.

modulationThe process of encoding information from one

signal (called the source) into another (called the carrier) by

modifying some characteristic(s) of the carrier. It is often

used in telecommunications when one type of signal must

be converted for transmission over an otherwise incompat-

ible medium.

multiplexer (mux)A device that merges several signals into

one composite signal for transmission over a single medium

or channel. A de-multiplexer (usually built into a mux)

reverses the process at the receiving end.

NAK (negative acknowledgment)Communications code

used to indicate that a message wasnt properly received or

that a terminal doesnt want to transmit. Contrast with

ACK.

networkA group of computers connected by cables or

other means and using software that enables them to share

equipment, such as printers and disk drives to exchange

information.

NIC (network interface card, pronounced nick)A printed

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