Fiber Optics Illustrated Dictionary - Part 38 doc

FCSI Profiles serve as guidelines for the implementation offiber channel systems that can be used by compo-nent manufacturers and systems and service integra-tors of fiber communications

Fiber Optics Illustrated Dictionary

Fibre Channel Loop CommunityFCLC A

Cali-fornia-based organization supporting and promoting

Fibre Channel technology with particular attention

to mass storage in arbitrated loop topologies The

FCLC merged into the Fibre Channel Assocation as

a working group in 1999

Fibre Channel Topologies

point-to-point topology

Direct connections between two N ports

wherein one is a server This is a

nonscalable topology by definition and

arbitration is not required

arbitrated loop topology

Atopology in which multiple devices can

share the media It is a middle solution

be-tween the limited point-to-point topology

and the more flexible but also more

com-plex fabric topology, a compromise

suit-able for small local area networks

(LANs) Because resources are shared,

only one device con connect at anyone

time to a shared resource Devices can be

chained or arbitrated through a Fibre

Channel hub

fabric topology

The most powerful and potentially

com-plex implementation of Fibre Channel,

fabric topology encompasses more than

one FC switch interconnected to other

de-vices through one or more ports F ports

enable connections to other F ports or to

Nports (node ports)

Fibre Channel specificationsFCS There are two

general aspects of FC specifications, the ANSI

Fi-bre Channel Standard (X3Tll) and FCSI FiFi-bre

Chan-nel Profiles developed by the Fibre ChanChan-nel

Asso-ciation (now the Fibre Channel Industry AssoAsso-ciation)

to assist implementors in understanding and

devel-oping the technology while maintaining

interoper-ability See Fibre Channel Standard, Fibre Channel

Industry Association

Fibre Channel StandardFCS Ahigh-speed,

block-oriented, serial, fully bidirectional data transfer

in-terface for interconnecting workstations,

main-frames, display peripherals, and storage devices

Both electrical and optical media are supported by

the standard FCS has been standardized by the ANSI

X3TII committee

The Fibre Channel Standard is intended to support

both wire and fiber optic systems, from 133 Mbps

to 1062 Mbps (and higher) at distances up to 10

ki-lometers (contrast this with a standard SCSI

electri-cal cable transmission, for example, which has a

practical distance of only a few feet) The actual

maximum distance is dependent upon the medium

and data rates For example, single-mode fiber can

transmit up to 10 kilometers, whereas shielded

twisted-pair wire has a limit of 50 to 100 meters, de-pending upon whether the data rate is 25 or 12.5 MBps Frame sizes may be up to 2,148 bytes, depend-ing upon the size of the payload (the informational content) Development is underway to support higher speeds (e.g., 10 Gbps)

There are three general topologies (architectures) described for Fibre Channel networks

FCS provides excellent opportunities for aggregat-ing peripherals under desks, or in server rooms and secure areas, for standardizing a wide variety ofcom-puter peripherals, and for increasing architectural flexibility in the placement ofequipment Because it

is a hot-swappable format, Fibre Channel devices can

be added to or removed from a network without pow-ering down the network

FCS is a hierarchical, layered architecture, with five layers defined from highest to lowest

Six data rate speeds have been defined as part of the Fibre Channel Standard

Cable Rate Payload Rate Max Distance

Mbaud MBps Mini-Coax 9IlmFiber

2125.0000 200 4250.0000 400

See F port, Firewire, FL port,Nport, storage area network See Fibre Channel Layers chart and other entries prefaced by Fibre Channel

Fibre Channel Systems InitiativeFCSI A group organized in 1993 to promote the interoperability, use, and distribution ofFibre Channel technologies FCSI Profiles serve as guidelines for the implementation offiber channel systems that can be used by compo-nent manufacturers and systems and service integra-tors of fiber communications technologies See Fi-bre Channel Industry Association

Fibreoptic Industry Association LimitedFlA.A professional organization representing suppliers, edu-cators, and installers in the fiber industry, inaugurated

in February 1990 The FIA is managed from the U.K

by the FIA Secretariat with support from a manage-ment council of elected individuals taken fromFIA

members and other supporting individuals The or-ganization includes a number of semi-autonomous regional offices http://www.fibreoptic.org.uk/ Fick's first lawThe mass movement ofatoms (flux) from one point to another in a given time frame is equal to the negative diffusivity times the delta con-centration (the mass per given volume) divided by the delta diffusion distance as expressed for a one-dimensional system by

F=-D(OC/&) For the condition C(A)=0, the equation can be

As applied to biological systems, the net rate of

dif-fusion of a gas across a fluid membrance is

propor-tional to (a) the difference in partial pressure, (b) to

the area ofthe membrane, and inversely propertional

to the membrane's thickness

Fick's second law describes the time-variant

diffu-sion ofatoms in a material for a one-dimendiffu-sional

sys-tem (e.g., unidirectional diffusion from a planar

sur-face) for a constant diffusion coefficient This

facili-tates approximations for various factors related to

diffusion See diffusion

FID Field Identifier, part ofan ISDN Service Profile

Identifier See SPID

FidoNetEstablished in1984by Tom Jennings with

the second node belonging to John Madill, this

net-worked bulletin board system (BBS) became a

ma-jor communications tool for techie discussions, email,

and file transfers as bulletin board operators all over

the country started to establish Fido boards for their

local users

fieldIn a scanning video broadcast display, a field is

every other line of the full picture frame Thus, it is

all the odd numbered lines taken together, or all the

even numbered lines taken together, in an interlaced

image

field, dataA record-holding or record-entering

en-tity in a database The definition offield types

facili-tates program setup, management, and data

manipu-lation by alerting the software as to the nature of the

information being entered into a field That is, a field

may be given a data type (number, string, date, etc.),

or it may be untyped, but either way this tells the

sys-tem something about the data

field modeIn video image capture, a mode that

cap-tures only half of the scan lines in order to save an

image in lower resolution, thus taking less storage

space See field, frame mode

field windingA mechanism for energizing

electro-magnets in a generator See winding

Field, Cyrus West (1819-1892) AnAmerican

indus-trialist who contributed significantly to the economic

and political negotiations involved in the first

trans-atlantic telegraph cable, originally completed in

Au-gust1858 and later successfully installed as a

per-manent cable The concept was championed in part

by Canadian inventor Frederic Gisborne, who

ap-pealed to the American business community for

fi-nancing so he could establish eastern Canadian

tele-graphic installations through a combination

ofsteam-ships and undetwater cables Maritime Canada was

a sparsely populated wilderness at the time, with a

great need for communications links and limited

re-sources for their development

As a youth, Field was apprenticed to a prominent and

successful merchant before setting up his own paper

manufacturing firm He thus had an established

net-work of contacts in the New York and Washington,

D.C areas that he could draw upon for support As a

successful businessman, he probably could have

projects, but the telegraph cable idea evidently fired his imagination After considering the feasibility of the project, with help from his brothers and other busi-ness associates, Field contacted influential people for technical assistance and support (e.g., Samuel Morse)

Cyrus Field - Transatlantic Cable Installer

Cyrus Field achievedfame for his contributions to the laying of the first transatlantic communications cable His portrait was widely used in articles and song sheets commemorating the historic event [Por-traitfrom the Mathew B Brady studio, ca 1850s Li-brary ofCongress American Memory collection.}

Over the next decade, Field, Taylor, Roberts, and Cooper made substantial investments in the venture, with the project's promotional lead, Cyrus Field, re-ceiving most of the public acclaim for the ambitious project

In time, the Canadian-American alliance interlinked maritime Canada and, after initial failure, linked Canada to the u.S through the Gulfof St Lawrence These early trial-and-error cable installations no doubt provided valuable technical experience facili-tating the development of longer, ocean-laid cables

In 1856, Field traveled to England on behalf of the transatlantic cable project and formed the Atlantic Telegraph Company In December 1861, George Opdyke wrote to President Abraham Lincoln in sup-port of the project No doubt other supsup-porters made similar appeals to prominent dignitaries The Library

of Congress and Cornell archives include examples

of correspondence and letters of introduction from Cyrus Field to prominent persons, including the Presi-dent These were turbulent times in America, how-ever, and the pursuit of a cable communication with the British Isles wasn't the easiest cause to champion

in view ofBritish-American relations In spite ofthe technical and political difficulties, success was finally

Fiber Optics Illustrated Dictionary

achieved after several failures and temporary

successes, with a permanent cable installed in the

mid-1860s Instantaneous intercontinental

communi-cation was now possible, a revolution that forever

changed humankind's commercial and social

inter-actions

After the laying of the transatlantic cable, Field

be-came an advocate for the public acquisition of

com-munications services To gamer support for this

con-cept, Field penned an article called "Government

Te-legraphy" for the North American Review in March

1886 that states, in part:

"It appears to me that the time has arrived when

the Government of the United States should

pur-chase, in the interest ofthe people, all the telegraph

lines in the country Communication by telegraph

has become almost as common, and quite as

nec-essary, as communication by letter As letters are

sent to all parts ofthe United States for two cents,

and papers and magazines at one cent for every

four ounces, so, I think, atelegraph message should

be sent to any part ofthe United States at the

low-est price at which experience has shown it possible

that the transmission can be effected "

Anillustrated history ofthe Atlantic Telegraph

Com-pany is available on the World Wide Web See

Gisbome, Frederic Newton; gutta-percha;

transatlan-tic cable http://www.atlantransatlan-tic-cable.com/

FIFSee Fractal Image Format

FIFOfirst in, first out.In programming, a means of

processing data so the fIrst item to be stored or placed

on a stack is the first to be fetched, moved, or

dis-carded Imagine a narrow vertical tube for gerbils (or

hamsters, if you prefer fluffy rodents); the first

ger-bil to squeeze in through the top is the first to slide

out the bottom In general terms of

telecommunica-tions, in a FIFO system the first person who calls is

the first to be referred to an agent

Fiber Optic Filament Spools

Spools ojfiber optic filament are soldfor a variety

of lighting and hobby applications, including signs,

lamps, and art pieces in sizes rangingfrom about 25

to 2.0 mm Sheathedfilaments that can be separated

from the main cable as needed are also available.

fllament 1 Afine metal conducting wire commonly

used in tubes and bulbs By passing a current through

a filament in a specialized, enclosed environment,it

becomes incandescent, giving offtight See cathode

2 A fine cylinder of glass or plastic In fiber optics technologies, glass or plastic filaments with good conducting properties (e.g., clear glass with a mini-mum of fabrication blemishes and impurities) are used as waveguides for the conduction of light sig-nals They are popular as novelty fiber optic lamps, signs, art pieces, and for communications technolo-gies See fiber optics

file A collection of associated data stored so that a pointer to the information identifies and encompasses the contents ofthat file as an accessible, readable unit, even ifstored in separate parts This is one ofthe most common units of storage in a computer system - file hierarc~ies, file folders, file types, and file manage-ment are all computer structures and processes con-structed to manage files

file attachment Most email systems are text-oriented 7-bit messaging media So how do you send some-one an 8-bit binary file? To meet this need, many text email systems have the capability of sending binary files as file attachments to a message Since binary files include symbols and characters which cannot be displayed in a plain text window, and since the sym-bols are not meaningful to humans, it is more practi-cal to send the file (which may be sound, graphics,

or a computer application) as an attachment, rather than as a postscript to the email text message.Inmost cases, all that is necessary is to specify the name of the file in the Attachment: text box or email message header, and the system will take care of the transfer

of the information

file cache An area of memory allocated by an oper-ating system or computer applications program to temporarily store a file that may need to be accessed

or modified frequently Many database and spread-sheet programs use file caches to allow quick updates and redisplays of information, and the data may also

be periodically stored on disk as a background task

so as not to lose information and updates in the case

of a software crash or power outage

file extension A syntactic convention that aids in identifying computer data file types There 8Je many categories ofcomputer files: text files, graphics files, sound files, and within these basic categories are many subcategories, such as JPEG, TIFF, etc A con-vention ofadding a period and a shortSUffIXto iden-tify the type of file, so it can be found at a glance, has become widespread, and some applications and systems will even enforce certain file extensions

Since the mid-1980s, every significant

microcom-puter and workstation level operating system except MS-DOS has allowed file extensions of reasonable length (up to 16, 32, 64, or 256 characters for the whole file name, depending upon the system) MS-DOS restricted its users to only three characters and enforced the use of the period (dot) as the file extension symbol Since there were so many DOS-based machines, users of other systems hact to

trun-cate file extensions (and the rest of the file name) when transferring files to other systems This imprac-tical three-character extension limit is still prevalent,

support longer filenames (it is still common to see

HTML file extensions on the Web listed as ".hOO"

instead of ".hool")

On most other systems, the dot (.) is not mandatory

for specifying the extension The user can save a file

with no dots or with a dozen dots However, since

several early systems in the 1970s required a dot,

users are used to this naming convention

On many systems, a file extension also lists a

ver-sion number, so backups and reviver-sion histories can

be maintained at all times For example, the

follow-ing extensions may be automatically generated:

~atimage.tiff.locmygreatimage.tiff;l

mygreatimage tiff 2 or mygreatimage tiff; 2

mygreatimage tiff 3 oc mygreatimage tiff; 3

If the default for the revision level is three, then the

next file to be saved under the same name will

su-persede the oldest file, in a first in, first out (FIFO)

sequence, so that no more than three files with the

same name are stored at anyone time This version

number extension/revision system is very handy

when something is saved accidentally, and the

pre-vious version needs to be retrieved

fIle gap Ablank inserted to indicate a stopping point,

or a division between sets of infonnation, especially

on a sequential file recording system On an audio

tape or digital data tape, a file gap indicates the

be-ginning or end of a song or file

file server Generally, a system on a network that

ad-ministrates the storage of and access to files, often

through a client/server model, in which multiple

us-ers make requests to the file server through the

cli-ent software This system reduces redundant storage

offiles on individual systems and makes it easier and

faster to update individual files The server also

handles file locks, so data files cannot be

simulta-neously updated and saved by multiple users

Usu-ally, a dedicated file server is equipped with high

stor-age capacity, and it may manstor-age security levels for

access to the files Network File System (NFS) is a

commonly used Unix file server system from Sun

Microsystems that is implemented on many

plat-fonns

file server, Frame Relay In a Frame Relay network,

the file server is a device that provides connections

with terminals, controls transmission flow, and

pro-vides end-to-end acknowledgment and error recovery

File Service Protocol FSP A file transfer protocol

somewhat similar to File Transfer Protocol (FTP)

originally developed for Unix by Wen-King SUo It is

a low-load (nonforking), reasonably robust protocol

that permits transfers to be resumed from the point

at which they stopped if the server goes down

tem-porarily or, ifdesired, allows for partial file transfers

from a specified point

FSP is somewhat like Anonymous FTP except that it

doesn't require a username and password For

iden-tification and logging purposes, the host domain of

the user is recorded It is also claimed that it is less

prone to server attacks than systems with FTP setVers

its transmission connections and uses the same port for communications See File Transfer Protocol fIle sharing Access by more than one user, sometimes

at the same time, depending on the nature ofthe data,

to files that may be on one system on a network or spread out over several workstations that are inter-accessible On the Apple Macintosh, file sharing is easily set up via utilities in the Control Panels so that passwords can be assigned and files shared with des-ignated users on the system On a larger network, a particular machine or set of machines, usually with large hard disk storage capacity, may be dedicated

to file serving and sharing activities See file server File Transfer Protocol FTP A user-level file shar-ing protocol established by the early 1970s on the ARPANET and now widely implemented on the

In-ternet in the form of FTP archive sites The concept

of FTP sites was to provide a simple, consistent means of presenting and accessing file information

on a variety of types of file archive sites, so the user could easily navigate the site and upload or down-load files unassisted In other words, FTP sites have

a consistent look and feel; once you've learned a few easy commands, you can log in, look around, and get what you need without having to worry about the in-dividual characteristics of the system on which the files are stored

Many FTP sites provide public access through a user login in which you type "anonymous" as the user-name, and your full email address as the password

If you have a Unix shell account with an FTP client, you simply type "ftp"(inalliowercase), followed by

"help" when it activates, to learn its basic commands and capabilities The inset shows an example of a simple anonymous FTP login

Inthe example session shown, the user logs in as anonymous, supplies a legitimate email address as the password, and is dropped into a limited en-vironment where basic directory traversing com-mands and file download comcom-mands can be used The message "Guest login ok, access restrictions apply."

is displayed This session is very typical in that the user is prompted to disconnect if logging of his or her activities is objectionable and is notified that there are restrictions The user's logon number is shown,

in addition to the total number of people on the sys-tem Ifthe system is at capacity, the user may be asked

to try again or may be provided with a message giving the addresses ofmirror sites (sites with the same files

in other locations)

For file transfers, the get command, followed by a

filename, will initiate a file download The

com-mands bye or quit will end a session.

On Unix systems, you can type "man ftp" at a shell prompt to read the manual pages for FTP, which in-clude a list of common commands FTP file down-load capability is built into most Web browsers and works transparently with many Web file archives Several variations of the File Transfer Protocol ex-ist, and cutdown, easier-to-implement versions have also been developed, which are described on the

Fiber Optics Illustrated Dictionary

Internet in various RFCs See File Service Protocol,

Simple File Transfer Protocol, Trivial File Transfer

Protocol, RFC 171, RFC 172, RFC 959

file transfer protocolIn its general sense, any

pro-gram that facilitates the movement of files from one

system to another, particularly through phone, null

modem or other serial data links, or the Internet There

are many file transfer protocols, but two of the most

popular implementations are ZModem, for telephone

line transfers, and File Transfer Protocol (FTP) for

Internet transfers Other popular programs include

Kermit, XModem, and YModem More detailed

in-formation is included in this dictionary under

indi-vidual listings for the various protocols

fIlmn.1 Athin membrane, skin, or coating 2 Athin,

light- and/or chemical-sensitive material commonly

used in the photographic industry 3 The collective

name for a sequential, related set ofstill frames, taken

together, form a story or cohesive idea that is viewed

by playing the frames through a projector Also called

movie

filter n 1 Aporous material through which mixtures

are screened in order to selectively prevent larger bits

of the mixture from passing through 2 A device or

material through which particular waves, frequencies,

or particles do not pass A filter may be used in

com-bination with another device, such as an amplifier,

in order to filter out noise, while propagating the

de-sired portion of a signal Electrical and audio filters

are common

fIlter, fIleFile filters are not necessarily

exclusion-ary tools, as in some senses of the word "filter," but

rather may be conversion utilities available in many

application programs to input or output files in a

for-mat that is not native to the application Thus, a TIFF

file might be imported into a paint program with a

proprietary format, through a filter, and may be

ported through another filter to a JPEG file, for

ex-ample, for use on the Web

A filter may also be coordinated with a database to

selectively provide access to higher priority messages

or processes, while filtering out, or queuing those of

lower priorities Email filters are especially useful to

those who get hundreds of messages a day, as often

happens on email mailing lists A good email client

will let you set up filters that file the messages in

sepa-rate folders to be selectively read later, so the user

can more easily determine which messages to check

first Exclusionary file filters also exist For example,

an email file filter may exclude all messages received

fromluser@hotmail.comor relegate them unread to

the bit bucket

fIlter, networkInnetwork transmissions, there are

physical filters and logical filters Logical filters

func-tion on every level ofthe system from low-end

oper-ating functions, to high-end user applications

Logi-cal filters employ algorithms to selectively block the

continuation ofcertain information, such as

extrane-ous packets, unrecognized characters, extra

informa-tion not supported by the receiving protocol,

un-wanted email, messages from sites operating

unlaw-fully, etc

filteringUsing physical or logical means to selec-tively permit access ofonly the desired information Thus, unwanted information can be screened out, or

a lower capacity system can be used to view or use part of the information according to its capabilities For example, filtering out parts of a transmitted im-age makes it possible to display it on a system with low resolution, or a slow image display, a solution that may be preferable to no image at all See com-pression, MPEG

filtering agent, filtering client Asoftware program that can be configured to selectively reject or keep information according to a set ofparameters or keys With the excess of information available through the Internet, filtering agents are increasing in importance See data mining

filtering trafficOn a network, the selective accep-tance or rejection of certain packets, messages, or processes according to a set of priorities and param-eters High and low usage times may also be factors

in setting up filtering instructions Traffic filtering is usually accomplished by combining a database with

a list ofpriorities See firewall

fm waveguideA structure that can be used in con-junction with circular waveguides to increase the range of wavelengths that can be transmitted, by at-taching a longitudinal metal fin

Financial Services Technology ConsortiumFSTC

A not-for-profit consortium of banks, financial ser-vices institutions, technology companies, govern-ment agencies, research labs, and educational insti-tutions FSTC supports and promotes collaborative research and technical projects affecting the finan-cial services industry in order to further the competi-tive health of the financial industry in the U.S http://www.fstc.org/

fmderAname used on several computer systems for applications that aid in locating information on a sys-tem, whether it be files, directories, or the specific content of files

FinderOn the Apple Macintosh, the graphical user interface and operating system processes through which the user interacts with the system Multifinder allows more than one program to be executed at a time and is available on the more recent versions of MacOS It is also a generic name for a file fmding tool that comes with the operating system

finesseInoptical resonating cavities, the number of round trips a light pulse can make from one reflec-tive surface to another and back before the signal dis-appears through scattering and attenuation

FingerThe name of an online information utility, based on the Finger Protocol, that allows the user to retrieve and display information about users ofa sys-tem, or the owner ofa particular account on the net-work, provided no firewalls exist to block thefinger

command (as a command it is spelled all in lower-case) Login and logout times may be displayed, or the length oftime since the last login Ifthe user que-ried has particular dot files configured, such as.plan (dot plan),additional information from this file will

be displayed Users often use the.plan file to list

or professional credentials See firewall.

Finger ProtocolA network information protocol

which is an elective proposed Draft Standard of the

IETF See finger, RFC 1288

Finkel, RaphaelA Finkel is probably best known

as the first disseminator ofthe infamous Jargon File,

distributed from Stanford University in 1975 He is

also the author or co-author ofhandbooks and

numer-ous articles on networks, data structures, and

com-puter algorithms See Jargon File, The

FIPSSee Federal Information Processing Standard

frrefightingTrying to fix something after the fact

Often used in a derogatory sense to indicate the

frus-tration of trying to rescue a situation that would not

have occurred ifproper steps or prevention methods

had been used in the first place The term describes

distressing, expensive catch-up or fix-up situations

resulting from bad management decisions For

ex-ample, shipping a software product before it is fully

tested and debugged can result in a great loss

ofcon-fidence on the part of customers, and enormous

ex-tra firefighting expense to the company in terms of

subsequent upgrades and tech support that would not

have been required if the product had been properly

completed before shipment

firewallA physical screen created to prevent the

spread of fire It may be a wall of heavy,

fire-resis-tance materials See wiring vault

firewall, networkAcomputer network security

con-figuration designed to limit completely or selectively

access to a system At one time, firewalls were

usu-ally implemented on a specific gateway machine, but

hardware and software firewalls now are set up in a

number ofways, using filters, proxies, and gateways

at the circuit level A network traffic firewall

exam-ines incoming packets and selectively lets them pass

through, and it may also edit outgoing traffic in

or-der to protect the identities ofthe senor-ders, as in some

government networks Many local area network

(LAN) frrewalls are one-way, with unlimited access

out of the LAN and selective access into the LAN

Systems with firewalls frequently log all activities

through the point or points of entry, with or without

notification See packet filtering, proxy server

FireWireFireWire technology, also known as

LLINK, is a real breakthrough for connecting a wide

variety of peripheral devices to computer networks

It was developed in the mid-1990s by Apple

Com-puter and quickly moved toward broader industry

standardization In 2001, the National Academy of

Television Arts and Sciences (NATAS) recognized

Apple's FireWire contribution to the multimedia

in-dustry by awarding the company the Primetime

Emmy Engineering Award

The FireWire serial communications data rate is fast,

up to 200 Mbps when it was first released, with 400

Mbps supported soon after FireWire cables are easy

to connect and hot-swappable (they can be plugged

and unplugged without rebooting the host computer)

A FireWire bus can support up to 63 devices,

com-pared to the seven devices commonly supported by

figuring, soitisn't necessary to set or keep track of peripheral ID numbers for the devices FireWire de-vices don't need to be terminated by the user

FireWire is a good standard for a world demanding high-bandwidth multimedia applications It's much faster than USB and supports isochronous data trans-fers, providing guaranteed bandwidth for realtime audio/video data streams Many vendors have devel-oped PCI-format FireWire cards and software driv-ers for computdriv-ers that don't have native support for FireWire Cards will typically support between one ::~S~;~~~~~~~~~l~~~:~I~fs '.

likely that most operating systems will soon provide native support for the FireWire (IEEE-1394x) stan-dard Peripheral hardware vendors supporting Fire-Wire include Canon,WC,Kodak, and Sony By Au-gust 2001, 60 GByte FireWire hard drives were avail-able for less than $200

In spring 2001, the 1394 Trade Association intro-duced an update to the FireWire standard, called 1394b The previous speed of400 Mbps was already ripping fast compared to previously common periph-eral bus standards, but the new standard increased this data rate even further, up to 3.2 Gbps over glass op-tical fiber media The updated format also uses a new bus arbitration scheme, called Bus Owner Supervi-sor Selector (BOSS) It enables pipelined unidirec-tional arbitration, in parallel with data transmission

By using bilingual mode, the 1394b specification is backwardly compatible with previous versions The new features of 1394 are availableinbeta mode

FIRMRFederal Information Resources Manage-ment Regulation

firmwareProgrammed circuitry that is semiperma-nent Software on a disk is easily changed and rewrit-ten Software on the circuitry of a microchip is not easily changed and rewritten In between these are EPROMs, erasable, reprogrammable chips which can

be changed with the right equipment, and which re-tain the information during a power-off

FIRSTSee Forum of Incident Response and Se-curity Teams

first call dateA record of the frrst time a subscriber line is used, sometimes usedinbilling or in settling disputes

firstin, first outSee FIFO

fish jobslangPhrase to describe a difficult wiring installation in which the wiring has to be pulled and threaded through constricted or hard-to-reach spaces

fish tapeslangA smooth-surfaced, nonconductive (e.g., steel) metal tape that is threaded through tight areas, such as a wall or cable conduit It is then at-tached to a cable so that it can be pulled more easily back through the wiring path See pulling eye

fish bone antennaAnantenna named for its resem-blance to the ribs of a fish because it includes a se-ries of coplanar antenna elements arranged in pairs

The fishbone antenna is used in conjunction with a balanced transmission line

Fiber Optics Illustrated Dictionary

Fisher, Yuval Author ofFractal Image Compression,

which describes the current knowledge of fractal

compression in down-to-Earth terms with C source

code examples See fractal transform

FITL See Fiber in the Loop

FIX Federal Internet Exchange

fIXed access unit FAU A wireless telephony

desig-nation for a wireless phone unit that is not intended

to be carried around, but rather to provide wireless

communications within a limited region Thus, local

wireless phone service can be installed without

go-ing through a local phone provider, much like a fancy

intercom unit, or it can be subscribed through an

al-ternatevendor as alimited cellular or PCS seIVice

Fixed End System F-ES Anonmobile data

commu-nications system through which a mobile subscriber

accesses landline network services F-ESs typically

comprise modems installed into desktop computers

See Cellular Digital Packet Data, Mobile End System

Fixed Radio Access FRA Local telephone service

based upon wireless radio technology transmitted to

an antenna attached to the subscriber's premises The

concept did not catch on until it was marketed to

con-sumers as plain old telephone service (POTS) with

enhancements, as opposed to new wireless

technol-ogy The concept originally was more prevalent in the

U.K than the U.S., but it is beginning to influence

vendorsinthe North American market In typical

in-stallations, the digital signal from the transceiver is

converted to analog and carried to various points on

the premises through the existing copper wire, but the

digital signals can also be fed directly through newly

installed fiber optic cables, an option that would be

of interest to individuals and businesses desiring

wideband high-speed services The local loop

con-cept, in which a network of about 20 base stations

could serve a community of40,000 population, is less

expensive to implement and serve than current

cel-lular systems and thus could serve aniche somewhere

between traditional telephone and mobile telephone

subscribers

fIXed satellite service FSS One oftwo divisions into

which Ku-band satellite broadcast services have been

split FSS operates in the 11.7 to 12.2 GHz range The

other isbroadcasting satellite service (BSS) See

Ku-band

Fixed Telecommunications Network Service

FTNS A category of licensed service recognized by

communications authorities in Hong Kong There are

various types of services that constitute FTNS,

in-cluding wireline, cable, wireless, and satellite.FTNS

Operators are assigned tariffs on the basis ofthe

spe-cific types of services they provide, such as voice or

data Changes in the provision of local FTNS were

made in 1995 when the Hong Kong Telephone

Company's franchise expired, and the service was

licensed instead to four companies

Fixed Wireless Access FWA In regions where the

cost ofinstalling wireline may be prohibitive, due to

rough terrain or sparse population, or where regional

growth outstrips wireline installation capacity, FWA

provides a long-term or temporary alternative It

combines radio-based phone service, in the place of the local wireline loop, with common carrier phone service See time division multiple access, code di-vision multiple access

Fizeau interferometer See interferometer, Fizeau

FK foreign key Adesignation in a key cryptography scheme See key, encryption

FL port On a Fibre Channel network, a switch that connects to a loop Middle priority addresses are as-signed to FL ports, giving them higher priority than

N ports (node ports) and lower priority (in terms of loop control) than an end loop(NLport) endstation port See F port

flag n 1 A device or signal used to attract attention

or to indicate the state ofa situation In software pro-gramming and network operation, flags are fre-quently used to indicate the state ofprocesses or vari-ables, often under changing conditions

FLAG Ltd Fiberoptic Link Around the Globe A commercial fiber services carrier with installations

of more than 18,000 miles of fiber optic cable in-stalled worldwide

flame resistant, flame retardant A medium that is inherently resistant to catching fire or spreading flames or is treated or manufactured to increase these retardant properties Flame resistant and retardant materials are used in many industries including con-struction, electrical installation, and clothing manu-facture

flammable Aproperty ofeasily catching fire or con-tinuing to bum readily

flange Arim or rib on an object to add strength or to aid in alignment

flash v On a phone or intercom system, to send a

sig-nal through the line by pressing the switch button on the handset holder or the button designated asajlash button The flash button is used on some local

multi-line systems to transfer a call and may be followed

by the keying in of the number of the extension flash button A button designated on a phone or in-tercom system to send a signal that is the same as pressing the switch button on the handset holder See flash, flash hook

flash cut See hot cut

flash hook See switch hook

flash interference In television transmission and dis-play, a flash is a very briefinterference, sufficient to distort the picture information

flash memory Atype ofnonvolatile, rewritable com-puter memory technology, developed by Intel, pro-viding an alternative to large storage devices Since flash memory is physically compact and doesn't lose its data when the device is not in use, it has been in-corporated into PCMCIA cards for portable comput-ing applications Flash memory is also startcomput-ing to be used in portable telephone devices and digital cam-eras See memory, PCMCIA

flash tube A bulb or tube used to create a bright, momentary burst ofillumination through application

of a high-voltage pulse One-time flash bulbs were used in older cameras; electronically activated, reusable bulbs are now common

connectors that are basically flat, that is, wide and

narrow Within each subset ofconnector types (power

cable connectors, data cable connectors, etc.) there

are usually some that are called flat connectors due

to their low profile Flat connectors typically contain

a single line ofpins, pads, or holes for coupling with

cables, backplanes, or components

For portable devices, a flat connector is a small,

low-resistance, narrow electronic connector This type of

connector is increasingly favored for low-power

por-table device slide-in connections for use in a

vari-ety of applications where quick and easy

connec-tions and disconnecconnec-tions are desired Examples

in-clude small cards that slide in and out ofdata readers

or small handheld devices that slide into cradles and

docking bays

flat panelAny of a number of types of display

sys-tems that are narrower and flatter than traditional CRT

displays These may be special flat panel CRTs, gas

plasma displays, liquid crystal displays (LCDs), or

light emitting diode displays (LEDs) Flat panel

dis-plays are especially favored on mobile systems, such

as computer laptops

flat panel CRTA type of cathode-ray tube (CRT)

color display technology in which the electron beams

are aimed parallel to the front of the display device,

then deflected 90 degrees onto the viewing surface

This configuration permits the construction ofa much

flatter, smaller, more convenient display device

While this technology is still relatively new and

ex-pensive, the bulkiness oftraditional CRTs makes the

flat panel CRT commercially attractive See faceplate,

fiber optic

flat plate antennaA commercial/industrial/military

satellite communications focusing antenna based on

microcircuit design It is similar to a common

para-bolic antenna, except that it incorporates a series of

concentric rings laid over a transparent sheet to

cre-ate a lens that can be used to redirect signals

flat rate serviceA very common subscriber billing

technique Flat rates usually arise in services where

the overhead ofkeeping track ofmany different types

and quantities of usage would cut into profits Flat

rate services are also attractive to many subscribers,

as they know in advance what it will cost and don't

have to watch the clock or keep track of usage In

computer network access and telephone services, flat

rate billing is very common Since users ofthese

ser-vices vary dramatically in time of access, connect

times, and types of services used while connected, it

probably is more economical in the long run to

as-sign average usage fees than totryto track and bill

widely varying usage Flat rates for businesses tend

to exceed those for residential use by roughly a

fac-tor of three, depending on the type of service Local

phone calls in many areas in North America are billed

on a flat rate In Europe and some parts of North

America, per-call charges are levied instead and

long-distance services are usually billed on a per-call

ba-sis The newer digital cellular technologies sometimes

have a flat rate billing option

flat-roofed building or aircraft carrier 2 The portion

of an antenna that lies horizontal

flat top antennaAnantenna that has two or more parallel, horizontally strung wires

flatbed scannerA type of desktop scanner that per-mits the object to be scanned to be placed directly on the scanning surface; the object lies flat and doesn't have to roll through a drum or other moving mecha-nism This type of scanner is preferred for scanning books and other large or three-dimensional objects

flavorA slang term for type or model Programmers

Eif~~t:i.;~~~~i~ri;nr~r~~~~~;!~:~:~~a

patibility issues The distinction is somewhat like a 'dialect,' in languages, or a 'model' in a type of car

FLCSee ferroelectric liquid crystals

FLCDferroelectric liquid crystal display See ferro-electric liquid crystal

FLEA memoryflux logic element array memory

The whimsical acronym for a type of computer memory developed by RCA in the early 1960s The FLEA was created photographically and was capable

of storing 128 bits of information Its processing speed was 100,000 items per second

Fleming, John Ambrose(1849-1945)AnEnglish electrical engineer who investigated the Edison ef-fect and experimented with improvements to wire-less receivers in 1904 By modifying an electron bulb

so that it incorporated two electrodes, and attaching

it to a radio receiving system, the radio waves could

be converted to direct current (DC) Unfortunately,

this new diode was not a significant improvement

over previous electron tubes, but it was important in the evolution towards more sophisticated tubes that

came later The most important of these was the tri-odein which L de Forest took the two-element Fleming tube as the basis for the invention of the

Audion,which included a controlling grid as a third element See two-electrode vacuum tube

Fleming oscillation valveAn electron tube devel-oped by J A Fleming, based on Edison's work with electric light bulbs This diode tube was in essence a two element rectifier While it did not achieve the practical utility of later tubes, it led to the

develop-ment of the triode by Lee de Forest.

Fleming's ruleSee right-hand rule

flickerA characteristic of display devices, such as cathode-ray tubes (CRTs), in which the scanning of the screen is visible to the human eye as a light-dark flashing flicker Flicker can result from a number of causes, including the quality ofthe monitor, the mode ofdisplay (interlace or noninterlace), or the speed of the screen refresh as the electron beam sweeps the screen Generally, slower sweeps will appear to flicker more, as do interlace screen modes

Apparent flicker is eliminated on better multiscan monitors Most individuals can comfortably watch displays that are refreshed at about 70 Hz to 80 Hz;

above that level, the trade-off in cost and computing

is not sufficient to justify the insignificant or

Fiber Optics Illustrated Dictionary

nonexistent improvement

While flickering on screens may be uncomfortable

to watch, sometimes an interlaced mode has a

prac-tical purpose, as when an NTSC-compatible signal

is being generated to output to video See

cathode-ray tube, frame, interlace, multiscan

flip-flop1 Quick reversal ofdirection or opinion 2

A circuit or logic state that can assume one or the other

of two stable states (on/off, high/low, etc.) Atrigger

circuit or toggle

floating pointAmathematical representation system

in which a number is expressed as a product of a

bounded number (mantissa) and apower ofscale

fac-tor (exponent) within a number base (e.g., base 10);

hence, 123.45 can be expressed as 12345 x 103

•

Floatingpointrefersto the flexibility inherent in

plac-ing the decimal point by adjustplac-ing the exponent

floating point unitFPU In computers, floating point

math coprocessing chips are often paired with

cen-tral processing units (CPUs) to carry the processing

load ofthe math calculations, which are usually

cycle-intensive, thus freeing the CPU for other tasks

floating selectionIn graphical user interfaces, a

se-lected text or image area that can be manipulated and

moved separately from its background; thus it appears

to float over the other elements on the screen

Float-ing a selected region is useful for cut and paste, drag

and drop, and image processing applications

floodI To inundate, overflow, or cover a broad area

all at once 2 In scanning and printing technologies,

flood lamps are often used to process plates and

pro-vide illumination for the recording of images 3 To

inundate with data, often unintelligible, as an

incen-diary or retaliatory action 4 The outpour of vast

quantities ofdigitally generated infonnation See core

dump, data mining

floodingI Overflowing, inundating 2 In networks,

a technique of sending many identical packets

through various routes so redundancy increases the

chances ofthe data reaching its destination 3 In

net-works, a deliberate act ofvandalism in which data is

directed toward a system, or an email address, to fill

the hard drive space or tie up the processor, to render

the system useless Users caught flooding are

usu-ally denied further access to a system See core dump,

mail bombing

FLOPfloating point operation Mathematical

ma-nipulation ofa floating point number FLOPS

(Float-ing Point Operations per Second) is often used to

describe and compare microprocessor speeds See

MFLOP

floppy diskette, floppy diskA thin, compact,

por-table, flexible, read/write, random-access data

stor-age medium originally encased in a soft protective

case or, later, a hard protective case Data is stored

and modified by rearranging magnetic particles on

the surface of the disk and, as such, the disk should

be kept away from magnetic surfaces to reduce risk

of loss Generally, magnetic media are not reliable

for long-tenn storage (see superparamagnetic)

floppy diskette driveFDD Adevice for reading and

writing data to a floppy diskette data storage medium

that became more prevalent in the early 1980s There was usually one floppy drive built into a computer and sometimes a second external drive would be available in place of a more expensive hard drive Prior to this, most consumer machines used tape drives to store data

FLOPSfloating point operations per second Amea-sure ofthe speed ofmathematical computations See FLOP

flow In packet networking, a sequence of packets with the same source and destination addresses and other similar characteristics The detection of a flow

by various routing and switching mechanisms can trigger flow-based processing of that sequence of packets to improve efficiency Flow detection may also include marking the flow with a label For ex-ample, a new virtual circuit (VC) may be set up for a packet flow, thus removing or reducing the need for routing until the end of the flow is detected Flow processing is a means of handling high-speed data through systems not nonnally capable of very high rates of packet transmission The bottleneck is the overhead in managing the IP datagrams associ-ated with the packets Cut Through Routing, devel-oped by Ipsilon (a commercial switch vendor), en-ables significantly faster IP routing by detecting classes ofIP flows and processing them accordingly When processed through a VC, the transmission can

be handled by a switch without individual routing The signaling between IP switches is handled with the General Switch Management Protocol (GSMP) and the Ipsilon Flow Management Protocol (IFMP) See General Switch Management Protocol, Ipsilon Flow Management Protocol

Flow Attribute Notification ProtocolFANP In packet-switched networks, a protocol for manage-ment ofcut-through packet fOIWarding functions tween neighbor nodes FANP indicates mapping be-tween a datalink connection and a packet flow to the neighbor node, and it helps nodes manage the map-ping infonnation This allows the bypass ofthe usual Internet Protocol (IP) packet processing by allowing routers to fOIWard incoming packets See RFC 2129 flowchartA somewhat standardized diagrammatic representation of processes, procedures, conditions, and directions of traffic or information flow Flow charts employ geometric shapes, symbols, and con-necting lines to indicate the relative importance and relationships of the concepts being illustrated Programmers are often required by managers to pro-vide flow charts of their software designs However, many argue that outlines and pseudocode are more useful in representing the relationships and flow within a software program than conventional flow charts because ofthe lack ofcorrespondence between human interface actions and the looping and jump-ing structure of the code itself (in other words, the order and frequency with which the user interacts with the software rarely corresponds to the order and frequency of the algorithms and procedures that en-able those functions to be executed) Another factor complicating the application of traditional

manage-complexity of the decision-making points in a

pro-gram and the inability to predict every instance and

sequence of events that the user might take in a

so-phisticated program with many options(itwould be

like trying to chart the moves in a chess game before

the game has begun)

Code usually changes many, many times before the

full program is developed, even when the flow

rep-resentation stays the same Programming is a

rela-tively young art and many of the algorithms are still

being invented as the software is being developed and

cannot be known in advance, before the problem is

actually solved Imagine trying to flow chart the high

school course selections for a four-year-old child

without knowing anything in advance about his

tal-ents, skills, and interests and then you can understand

the difficulty of flow charting a software program

before it is written Thus, flow charts are best seen as

tools for conveying to management and co-workers

the general goals and structures of a project, but not

as efficient tools for developing the individual

com-ponents of the computer algorithms themselves,

which must be worked out as they are encountered

FLOW-MATICSeeB-O

Floyd-SteinbergAdithering algorithm, i.e., a means

of creating a perceptual tone or range of tones by

in-termixing colors related to those tones to create the

illusion of more colors Dithering is one way of

stretching a limited palette to make it appear as

though there are colors that are not actually available

Dithering works best with dots of light or color that

are very small, too small for the human eye to resolve

Inthe Floyd-Steinberg error diffusion algorithm, the

error between the approximate output value ofa pixel

and the actual value of a pixel is sequentially diffused

toits near neighbors See dithering

FLTSAT, FLTSATCOMThe U.S Naval fleet

com-munications satellite system that is one ofthe primary

U.S satellite communications systems along with the

Defense Satellite Communications System (DSCS)

and the Air Force Satellite Communications

(AFSATCOM) Together, the three systems comprise

the Military Satellite Communications

(MILSATCOM) system Control of the systems is

handled through the Air Force Satellite Control

Net-work (AFSCN)

FLTSATCOM was developed in the early 1970s to

provide communications for seagoing vessels,

air-craft, and U.S military ground crews worldwide In

addition to Naval and Air Force communications,

FLTSAT was designed to provide fast

communica-tions between the U.S President and Commanding

Officers

Transmissions are received by several hundred fixed

and mobile user stations on sea, air, and ground

ter-minals in addition to Communication Area Master

Stations (CAMS) in the U.S., Guam, and Italy

Chan-nels are allocated to the Navy, Air Force, and

Com-mand The first units were launched in the late 1970s,

with additional units added to the system in the 1980s

The geographical area covered by the

near-geosyn-grees north to about 70 degress south

In 1991, operational control ofsatellite programs was turned over to the 3D Satellite Control Squadron (3 SCS) which became the 3D Space Operations Squad-ron (3 SOPS) Then, in 1996, FLTSAT constellations were turned over from 3 SOPS to the Naval Satellite Operations Center in California

The FLTSATCOM Laboratory has a computer simu-lation of the satellite system (minus the radio fre-quency capabilities) provided by The Aerospace Cor-poration that gives a graphical representation of the satellite and its operations

When fully deployed, a FLTSAT unit resembles a trashcan with an umbrella on one end (the parabolic antenna) and rectangular, solar array' elephant ears' protruding from the central body The FLTSAT sys-tems incorporate a number of antennas in different wave bands, including S-band, UHF, EHF, and SHF (Super High Frequency) radio frequencies and have

an operational life of about five years They weigh approximately one to two tons each and are about the size of a large motorhome,withthe solar panel ears extending to over 40 feet It is expected that the UHF Follow-On (UFO) system will eventually supersede the FLTSAT constellation

fluorescent lampA fluorescent bulb used for lamps typically consists of a long glass tube equipped with

an electrode at each end, with specialized vapor and gases sealed inside the tube When electricity passes through the tube, light waves are emitted, causing phosphors coated on the inside of the tube to glow Manufactured since the late 1930s, the fluorescent lamp doesn't use a filament and provides more light than an incandescent lamp for the same amount of current Since less current is required, the bulb emits less heat Fluorescent lamps manufactured before

1978 may contain PCBs in the ballasts and should

bedisposed ofaccording to guidelines for PCB disposal

to avoid contaminating landfills and waterways flutter1 Arapid, repetitive, agitated back-and-forth movement; any erratic vibration or oscillation In most systems, flutter is an undesirable characteristic that interferes with the main signal See drift, wow

2 Undesirable phase distortion variations that may result from more than one frequency transmitting at the same time 3 In radio terminology, also loosely called drift and wow

flutter bridgeA device to measure flutter (undesir-able variations from a constant oscillation, move-ment, or signal) It is used for testing and diagnostic purposes for various playback devices that should be playing at a constant speed, such as phonographs, tape recorders, film projectors, or disc players

flutter rateThe speed at which an oscillating body moves back and forth, commonly expressed in units per second or minute

flux 1 Stream, continued flow 2.Anexpression of the rate of transfer across or through a unit area of a given surface, per unit of time See watt 3 A sub-stance used to facilitate the fusing ofmaterials, as the use ofrosin in soldering or welding 4 Magnetic lines