CD-ROM Data 1996 December/CD-ROM DATA 96.ISO/INTERNET/OFFLINE/COMPUTER/CDEDEMO.ZIP/CDE.TXT

Text File | 1996-07-17 | 165.7 KB | 6,557 lines

(c) 1981-1996 The Computer Language Company Inc.
All rights reserved. Demo Version, July 1996

INTRO.BMP











A/D converter
(Analog to Digital Converter)  A device that
converts continuously varying analog signals from
instruments that monitor such conditions as
movement, temperature, sound, etc., into binary
code for the computer.  It may be contained on a
single chip or can be one circuit within a chip.
See modem and codec.  Contrast with D/A converter.


AD_CONV.WMF

A/D Converter





ABI
(Application Binary Interface)  A specification for
a particular hardware platform and operating
system.  It is one step beyond the application
program interface (API), which defines the calls
from the application to the operating system.  The
ABI defines the API plus the machine language for a
particular CPU family.  An API does not ensure
runtime compatibility, but an ABI does, because it
defines the machine language, or runtime, format.


ABI.WMF

ABI and API Relationship





abort
(1) To exit a function or application without
saving any data that has been changed.

(2) To stop a transmission.



About this database
The full version of this database contains more
than 9,000 entries and more than 700 illustrations
and photographs on CD-ROM.  Look up "order form"
for ordering information.

    This product has been more than 15 years in the
making.  It started out in 1981 as the book, The
Computer Glossary, a 330-term compendium to Alan
Freedman's computer literacy seminars.  By 1989,
the 4th edition contained 3,500 terms with 400
illustrations and won the "Best Reference Book of
the Year" award from Computer Book Review.

    From 1990 to 1996, text-only versions were
available on disk for DOS and Windows.  In 1996, an
entirely new Windows version was released and
pictures were included for the first time.  The
Glossary was renamed Computer Desktop Encyclopedia
to reflect the true scope of the product today.

This Demo
This demo version contains a small sample of the
types of entries in the full version.  However,
none of the entries in this version are as complete
and as in-depth as the full version.

    Nevertheless, you can get the feel of the
product and see in an instant how easy it is to
use.





abstract class
Also called an abstract superclass, in object
technology, it is a class created as a master
structure.  No objects of an abstract class are
created, rather subclasses of the abstract class
are defined with their own variations, and the
subclasses are used to create the actual objects.



accelerator
A key combination used to activate a task.  See
accelerator board and graphics accelerator.



accelerator board
An add-in board that replaces the existing CPU with
a higher performance CPU.  See graphics
accelerator.



access
To store data on and retrieve data from a disk or
other peripheral device.   See access arm, access
method and Microsoft Access.



ACM
(Association for Computing Machinery, 1515
Broadway, New York, NY 10036, 212/869-7440)  A
membership organization founded in 1947 dedicated
to advancing the arts and sciences of information
processing.  In addition to awards and
publications, ACM also maintains special interest
groups (SIGs) in the computer field.

 In the full version of this software, all the
 major associations in the field are included
 as entries.  A list of these associations is
 also included.





ActiveMovie
A video programming interface (API) from Microsoft
for Windows 95 and NT that provides playback of
MPEG, AVI and QuickTime video as well as WAV audio.
It can decode MPEG movies in software and display
them full screen at 24 fps on a 90MHz Pentium.



ActiveX
An umbrella term for Microsoft products that
enhance Internet usage.  Much of the publicity has
centered around Active X controls, which are OLE
controls (OCXs) that have been specialized to run
in the Web.  This allows a huge variety of pre-
built functions to be activated within intranets as
well as the Internet.



Ada
A high-level programming language developed by the
U.S. Department of Defense along with the European
Economic Community and many other organizations.
It was designed for embedded applications and
process control but is also used for logistics
applications.  Ada is a Pascal-based language that
is very comprehensive.

    Ada was named after Augusta Ada Byron (1815-
1852), Countess of Lovelace and daughter of Lord
Byron.  She was a mathematician and colleague of
Charles Babbage, who was developing his Analytical
Engine.  Some of her programming notes for the
machine have survived, giving her the distinction
of being the first documented programmer in the
world.

    The following Ada program converts Fahrenheit to
Celsius:

 with Text_IO;
 procedure Convert is
 package Int_IO is new Text_IO.Integer_IO(Integer);
 Fahrenheit : Integer;
 begin
  Text_IO.Put_Line("Enter Fahrenheit");
  Int_IO.Get(Fahrenheit);
  Text_IO.Put("Celsius is ");
  Int_IO.Put((Fahrenheit-32) * 5 / 9);
  Text_IO.New_Line;
 end Convert;



 In the full version of this software,
 all the major programming languages are
 explained.  The same example of changing
 Fahrenheit to Celsius is included so you can
 compare the differences in syntax.





Adobe
(Adobe Systems, Inc., Mountain View, CA)  Founded
in 1982 by Dr. John Warnock, Adobe helped pioneer
desktop publishing with its fonts and applications.
Initially developed for the Macintosh, Adobe's
PostScript fonts have become the industry standard
among graphics and printing service bureaus.  Adobe
PhotoShop and Adobe Type Manager are examples of
world-class software that spearheaded the industry.

    In 1995, Adobe acquired Aldus Corporation,
makers of PageMaker, turning Adobe into the
preeminent desktop publishing software company.

 In the full version of this software,
 backgrounders on the major hardware and
 software vendors are included.





AmCoEx
See used computers and computer exchange.

 In the full version of this software, the
 latest index of used computer prices is
 included from the American Computer Exchange.
 Find out how much a used desktop computer,
 laptop or printer is worth on the market.





America Online

 In the full version of this software, a
 description of all the major online services
 are included.





analog
A representation of an object that resembles the
original.  Analog devices monitor conditions, such
as movement, temperature and sound, and convert
them into analogous electronic or mechanical
patterns.  For example, an analog watch represents
the planet's rotation with the rotating hands on
the watch face.  Telephones turn voice vibrations
into electrical vibrations of the same shape.
Analog implies continuous operation in contrast
with digital, which is broken up into numbers.


Advantages and Disadvantages
Of Analog Techniques
Traditionally, audio and video recording has been
analog.  Sound, which is continuously varying air
vibrations, is converted into analogous electrical
vibrations.  Video cameras scan their viewing area
a line at a time and convert the infinitely varying
intensities of light into analogous electrical
signals.

    The ability to capture the subtle nature of the
real world is the single advantage of analog
techniques.  However, once captured, modern
electronic equipment, no matter how advanced,
cannot copy analog signals perfectly.  Third and
fourth generations of audio and video recordings
show marked deterioration.

    By converting analog signals into digital, the
original audio or video data can be preserved
indefinitely and copied over and over without
deterioration.  Once continuously varying analog
signals are measured and converted into digital
form, they can be stored and transmitted without
loss of integrity due to the accuracy of digital
methods.

    The key to conversion is the amount of digital
data that is created from the analog signal.  The
shorter the time interval between samples and the
more data recorded from that sample, the more the
digital encoding reflects the original signal.



ANALOG.WMF

Analog Concepts
There are many analog systems.  Watch hands are
analogous to the earth's rotation.  Analog
telephones turn air waves into analogous
electrical waves.


CARRIER.WMF

Analog Radio
Radio broadcasting uses analog transmission.
 The sound waves are wrapped in a carrier
frequency unique to each station in the area.
The sound is maintained in analog
form throughout the entire chain from
recording microphone to the listener's
speaker.





AppleTalk
Apple's local area network architecture introduced
in 1985.  It supports Apple's proprietary LocalTalk
access method as well as Ethernet and Token Ring.
The AppleTalk network manager and the LocalTalk
access method are built into all Macintoshes and
LaserWriters.

    With other products from Apple and third
parties, AppleTalk can run in PCs, VAXs and UNIX
workstations.  Since AppleTalk is patterned after
the OSI model, it is a routable protocol that
contains a network layer (OSI layer 3).



application partitioning
Separating an application into components that run
on clients and multiple servers in a client/server
environment.  Programming languages and development
systems that support this architecture, known as
three-tier client/server, may allow the program to
be developed as a whole and then separated into
pieces later.  Development systems are
differentiated by their ability to perform
partitioning as a mainstream function in a high-
level language or with visual programming (drag &
drop) versus having to write chunks of code in C.

    Application partitioning is an important
capability for migrating legacy systems onto
client/server environments.  In many business
applications, there is alot of processing that
should be done centrally in a server and not in
each client machine.  Such programs are either too
demanding and process intensive for the client or
they represent proprietary business logic that
should not be replicated all over the enterprise.
The centralized mainframe has always made alot of
sense for many applications.  Partitioning the
logic onto multiple servers emulates this approach
in a client/server environment.


Who's Doing It?
Application partitioning can always be accomplished
by writing 3GL code.  However, with today's push
for rapid application development (RAD), writing in
a traditional programming language takes time.
Newer client/server development systems such as
Forte and DYNASTY provide application partitioning
at the 4GL level, and it is being included in
upgrades to existing development systems.

    The OSF's Distributed Computing Environment
(DCE) standard is expected to become popular for
three-tier client/server, because it provides a
standard for accessing programs and databases no
matter where they are located.





ASCII chart

╔══════════════════════════════╦═════════════════╗
║         Standard ASCII       ║ Extended ASCII  ║
║  The first 32 characters are ║      (DOS)      ║
║        control codes.        ║                 ║
║                              ║                 ║
║ 0 Null            │33 !│ 81 Q║128 Ç│174 «│220 ▄║
║ 1 Start of heading│34 "│ 82 R║129 ü│175 »│221 ▌║
║ 2 Start of text   │35 #│ 83 S║130 é│176 ░│222 ▐║
║ 3 End of text     │36 $│ 84 T║131 â│177 ▒│223 ▀║
║ 4 End of transmit │37 %│ 85 U║132 ä│178 ▓│224 α║
║ 5 Enquiry         │38 &│ 86 V║133 à│179 ││225 ß║
║ 6 Acknowledge     │39 '│ 87 W║134 å│180 ┤│226 Γ║
║ 7 Audible bell    │40 (│ 88 X║135 ç│181 ╡│227 π║
║ 8 Backspace       │41 )│ 89 Y║136 ê│182 ╢│228 Σ║
║ 9 Horizontal tab  │42 *│ 90 Z║137 ë│183 ╖│229 σ║
║10 Line feed       │43 +│ 91 [║138 è│184 ╕│230 µ║
║11 Vertical tab    │44 ,│ 92 \║139 ï│185 ╣│231 τ║
║12 Form feed       │45 -│ 93 ]║140 î│186 ║│232 Φ║
║13 Carriage return │46 .│ 94 ^║141 ì│187 ╗│233 Θ║
║14 Shift out       │47 /│ 95 _║142 Ä│188 ╝│234 Ω║
║15 Shift in        │48 0│ 96 `║143 Å│189 ╜│235 δ║
║16 Data link escape│49 1│ 97 a║144 É│190 ╛│236 ∞║
║17 Device control 1│50 2│ 98 b║145 æ│191 ┐│237 φ║
║18 Device control 2│51 3│ 99 c║146 Æ│192 └│238 ε║
║19 Device control 3│52 4│100 d║147 ô│193 ┴│239 ∩║
║20 Device control 4│53 5│101 e║148 ö│194 ┬│240 ≡║
║21 Neg. acknowledge│54 6│102 f║149 ò│195 ├│241 ±║
║22 Synchronous idle│55 7│103 g║150 û│196 ─│242 ≥║
║23 End trans. block│56 8│104 h║151 ù│197 ┼│243 ≤║
║24 Cancel          │57 9│105 i║152 ÿ│198 ╞│244 ⌠║
║25 End of medium   │58 :│106 j║153 Ö│199 ╟│245 ⌡║
║26 Substitution    │59 ;│107 k║154 Ü│200 ╚│246 ÷║
║27 Escape          │60 <│108 l║155 ¢│201 ╔│247 ≈║
║28 File separator  │61 =│109 m║156 £│202 ╩│248 °║
║29 Group separator │62 >│110 n║157 ¥│203 ╦│249 ∙║
║30 Record separator│63 ?│111 o║158 ₧│204 ╠│250 ·║
║31 Unit separator  │64 @│112 p║159 ƒ│205 ═│251 √║
║32 Blank space     │65 A│113 q║160 á│206 ╬│252 ⁿ║
║                   │66 B│114 r║161 í│207 ╧│253 ²║
║                   │67 C│115 s║162 ó│208 ╨│254 ■║
║                   │68 D│116 t║163 ú│209 ╤│255  ║
║                   │69 E│117 u║164 ñ│210 ╥│     ║
║                   │70 F│118 v║165 Ñ│211 ╙│     ║
║                   │71 G│119 w║166 ª│212 ╘│     ║
║                   │72 H│120 x║167 º│213 ╒│     ║
║                   │73 I│121 y║168 ¿│214 ╓│     ║
║                   │74 J│122 z║169 ⌐│215 ╫│     ║
║                   │75 K│123 {║170 ¬│216 ╪│     ║
║                   │76 L│124 |║171 ½│217 ┘│     ║
║                   │77 M│125 }║172 ¼│218 ┌│     ║
║                   │78 N│126 ~║173 ¡│219 █│     ║
║                   │79 O│127 ║     │     │     ║
║                   │80 P│     ║     │     │     ║
╚═══════════════════╧════╧═════╩═════╧═════╧═════╝

 In the full version of this software, ASCII
 charts in both decimal and hexidecimal are
 included.  The EBCDIC chart is also included.





ATM
^(1) (Asynchronous Transfer Mode)
^(2) (Automatic Teller Machine)
^(3) See Adobe Type Manager.

(1) (Asynchronous Transfer Mode)  A network
technology for both LANs and WANs that supports
realtime voice and video as well as data.  The
topology uses switches that establish a circuit
from input to output port and maintain that
connection for the duration of the transmission.
This connection-oriented technique is similar to
the analog telephone system.  ATM is defined in the
Broadband ISDN (BISDN) standard.

    ATM is scalable and supports transmission speeds
of 25, 100, 155, 622 and 2488 Mbps.  Switched ATM
service is expected to be offered by the common
carriers, providing bandwidth on demand.

    ATM is also used as a LAN technology in high-
speed workstations and PCs for demanding
applications such as imaging and video development.
The fervor around ATM has been the ease of future
network management when all desktops, backbones and
wide area services use the same ATM topology.

^Cell Switching
ATM works by chopping all traffic into 53-byte
cells, or packets.  This fixed-length unit allows
very fast switches to be built, because the
processing associated with variable-length packets
is eliminated (finding the end of the frame).  The
small ATM packet also ensures that voice and video
can be inserted into the stream often enough for
realtime transmission.

^Quality of Service
The ability to speficy a quality of service is one
of ATM's most important features, allowing voice
and video to be transmitted smoothly.  Constant Bit
Rate (CBR) guarantees bandwidth for realtime voice.
Variable Bit Rate (VBR) is used for compressed
video.  Available Bit Rate (ABR) adjusts bandwidth
for bursty LAN traffic.  Unspecified Bit Rate (UBR)
provides no guarantee.

^Integration with Legacy LANs
Network applications use protocols, such as TCP/IP,
IPX, AppleTalk and DECnet, and there are tens of
millions of Ethernet, Token Ring and FDDI client
stations in existence.  ATM has to coexist with
these legacy protocols and networks.

    LAN Emulation (LANE), defined by the ATM Forum,
interconnects legacy LANs by encapsulating packets
into LANE packets and then converting them into ATM
cells.  It supports existing protocols without
changes to Ethernet and Token Ring clients, but
uses traditional routers for internetworking
between LAN segments.  LAN Emulation does not
provide ATM quality of service.  See LAN Emulation.

    MPOA is an ATM standard that routes legacy
protocols while preserving ATM quality of service.
Expected to be finalized in late 1996, Newbridge
Networks has already implemented MPOA in its edge
devices (LAN to ATM devices).  See MPOA.

    CIF is a recent technique from Cornell
University that utilizes existing Ethernet clients
and provides the quality of service associated with
ATM.  It carries ATM cells directly within Ethernet
frames.  See CIF.

Summary
ATM is considered the most effective networking
technology to meet future needs, and most large
organizations have either installed or have plans
for ATM backbones.  However, new technologies
emerge all the time.  For example, Gigabit Ethernet
may provide an alternative to ATM.  Expected in the
1997 timeframe, it offers high speed and
compatibility with existing Ethernets.  Fibre
Channel is another high-speed transmission system
that offers gigabit speeds.  Although used mostly
for peripheral transfer, when set up in a switched
network configuration, Fibre Channel offers a
billion bits between stations.  As with everything
else in this fast-moving industry, there are always
new approaches on the horizon.  Stay tuned!

(2) (Automatic Teller Machine)  A banking terminal
that accepts deposits and dispenses cash.  Stand
alone or online to a central computer, ATMs are
activated by inserting a cash or credit card that
contains the user's account number on a magnetic
stripe.


ATMCOMM.WMF


ATM (Asynchronous Transfer Mode)
This diagram shows ATM switches used as a network
backbone.  Edge devices convert LAN packets, such
as Ethernet and Token Ring, into ATM cells and
vice versa.



ATM.WMF

ATM (Automatic Teller Machine)
This is the ATM everyone can relate to.





AV drive
(Audio Visual drive)  A hard disk drive that is
optimized for audio and video applications.
Transferring analog high-fidelity audio and video
signals onto a digital disk and playing them back
at high performance levels requires a drive that
can sustain continuous reads and writes without
interruption.  AV drives are designed to postpone
thermal recalibration when reading and writing so
that long data transfers will not be interrupted,
and frames will not be lost.



backup types
The selection of files for backup purposes.

^    Full Backup
    Backs up all selected files.

^    Differential Backup
^    Backs up selected files that have been changed.
^    This is used when only the latest version of a
    file is required.

^    Incremental Backup
^    Backs up selected files that have been changed,
^    but if a file has been changed for the second or
^    subsequent time since the last full backup, the
^    file doesn't replace the already-backed-up file,
^    rather it is appended to the backup medium.
^    This is used when each revision of a file must
    be maintained for backup.





band printer
A line printer that uses a metal band, or loop, of
type characters as its printing mechanism.  The
band spins horizontally around a set of hammers.
When the desired character is in front of the
selected print position, the corresponding hammer
hits the paper into the ribbon and onto the
character in the band.  This is not to be confused
with band printing, which is a method for sending
output to the printer.


BANDPRNT.WMF

Band Printer Mechanism
The hammer pushes the paper into the type slug
when it has moved to the proper position.





baud
(1) The signalling rate of a line.  It's the
switching speed, or number of transitions (voltage
or frequency changes) that are made per second.
Only at low speeds are bauds equal to bits per
second; for example, 300 baud is equal to 300 bps.
However, one baud can be made to represent more
than one bit per second.  For example, the V.22bis
modem generates 1200 bps at 600 baud.

(2) Commonly (and erroneously) used to specify bits
per second for modem speed; for example, 1200 baud
means 1200 bps.  See previous paragraph.



Bay Networks
(Bay Networks, Inc., Santa Clara, CA)  A
communications products company that is the merger
in late 1994 of SynOptics Communications, Inc.,
Santa Clara, CA, and Wellfleet Communications,
Inc., Billerica, MA.  At the time of the merger,
SynOptics was number #1 in hubs, and Wellfleet was
number #2 in routers.

    The Bay name comes from Santa Clara being
located in the California Bay area and Billerica,
located in Massachusetts, which is known as the Bay
State.

 In the full version of this software,
 backgrounders on the major hardware and
 software vendors are included.





Bernoulli Box
A removable disk drive for personal computers from
Iomega Corporation, Roy, UT.  It uses a type of
floppy disk technology that provides hard disk
speeds and a very reliable and transportable
storage medium.  The first Bernoulli Box in 1983
used a 10MB, 8" cartridge.  In 1987, 20MB 5.25"
cartridges were introduced and later 44MB and 90MB.
The MultiDisk 150 drive accepts 35, 65, 90, 105 and
150MB cartridges.  In 1994, the 230MB disk was
introduced that is backward compatible to the 44MB
disks.  Bernoulli drives use the SCSI interface.

    Unlike a hard disk in which the read/write head
flies over a rigid disk, the Bernoulli floppy is
spun at high speed and bends up close to the head.
Upon power failure, a hard disk must retract the
head to prevent a crash, whereas the Bernoulli
floppy naturally bends down.  See Bernoulli
principle and Zip disk.


STRBERN.WMF
STRSYQ.WMF

 In the full version of this software, all the
 magnetic tape, magnetic disk and optical disk
 technologies are explained and diagrams are
 included.





BinHex
A utility and encoding format that originated on
the Macintosh which is used to convert binary files
into 7-bit ASCII for communications over the
Internet.  The Internet only supports seven bits.
See UUencode, Wincode and MIME.



bit
(BInary digiT)  The smallest element of computer
storage.  It is a single digit in a binary number
(0 or 1).  The bit is physically a transistor or
capacitor in a memory cell, a magnetic spot on disk
or tape or a high or low voltage pulsing through a
circuit.

    Groups of bits make up storage units in the
computer, called characters, bytes, or words, which
are manipulated as a group.  The most common is the
byte, made up of eight bits and equivalent to one
alphanumeric character.

    Bits are widely used as a measurement for
transmission.  Ten megabits per second means that
ten million pulses are transmitted per second.  A
16-bit bus means that there are 16 wires
transmitting the bit at the same time.

    Measurements for storage devices, such as disks,
files and databases, are given in bytes rather than
bits.  See space/time.


BITS1.WMF

Storage - Making it Smaller
Making the spot or cell smaller increases the
storage capacity.  Our disks hold staggering
amounts of data compared to 10 years ago,
yet we still want more.
Look up holographic storage for a look into a
fascinating future storage technology.



BITS2.WMF

Transmission - Making it Faster
The bit is transmitted as a pulse of high or low
voltage.  Speed is increased by making the
transistors open and close faster, which is a
combination of making the microscopic elements
within the transistor smaller and more durable.

Transmitting pulses internally in the computer is
much simpler than out over a network, where they
are influenced by long distances and interference.
The telephone companies have been the pioneers in
installing high-speed optical trunks throughout
the country.




bit depth
(1) The number of bits used to hold a pixel.  Also
called color depth and pixel depth, the bit depth
determines the number of colors that can be
displayed at one time.  Digital video requires at
least 15 bits, while 24 bits produces realistic TV-
like colors.


      Color depth     Total number of colors
       4-bits         16
       8-bits         256
      15-bits         32,768
      16-bits         65,536
      24-bits         16,777,216
      32-bits         16,777,216 + alpha channel


(2) Bit depth can refer to any coding system that
uses numeric values to represent something.  The
depth, or number of bits, determines how many
discrete items can be represented.





bitmap
A binary representation in which a bit or set of
bits corresponds to some part of an object such as
an image or font.  For example, in monochrome
systems, one bit represents one pixel on screen.
For gray scale or color, several bits in the bitmap
represent one pixel or group of pixels.  The term
may also refer to the memory area that holds the
bitmap.

    A bitmap is usually associated with graphics
objects, in which the bits are a direct
representation of the picture image.  However,
bitmaps can be used to represent and keep track of
anything, where each bit location is assigned a
different value or condition.


BITMAP.WMF

A Monochrome Bitmap
The left half of this diagram shows the bits in
the bitmap, and the right half depicts
what would show on screen.  In monochrome systems,
one bit is used to represent one pixel.  Images
that are scanned into the computer are turned into
bitmaps, and bitmaps can be created in a paint
program.





Blenheim shows

 In the full version of this software, the
 annual schedules of upcoming major computer
 shows are included.





boot sector
An area on disk (usually the first sectors in the
first disk partition) reserved for the operating
system.  On startup, the computer looks in the boot
sectors for the operating system, which must be
loaded first.



bot
(1) (roBOT)  A program used on the Internet that
performs a repetitive function such as posting a
message to multiple newsgroups or searching for
information.  Bots are also used to keep a channel
open on the Internet Relay Chat (IRC).
Increasingly, the term is used for all variety of
macros and intelligent agents that are Internet or
Web related.

(2) (BOT)  Beginning of tape.  Similar to BOF.



breakout box
A device inserted into a multiple-line cable for
testing purposes that provides an external
connecting point to each wire.  A small LED may be
attached to each line, which glows when a signal is
present.


BREAKBOX.WMF

Breakout Box





broadcast storm
Excessive transmission of broadcast traffic in a
network.  Broadcast storms can be lessened by
properly designing and balancing the number of
nodes on each network segment.



BSD UNIX
(Berkeley Software Distribution UNIX)  A version of
UNIX developed by the Computer Systems Research
Group of the University of California at Berkeley
from 1979 to 1993.  BSD enhancements, known as the
"Berkeley Extensions," include networking, virtual
memory, task switching and large file names (up to
255 chars.).  BSD's UNIX was distributed free, with
a charge only for the media.  USL code is contained
in most BSD versions, and users require a valid USL
license in such cases.

    Bill Joy ran the group until 1982 when he co-
founded Sun Microsystems, bringing 4.2BSD with him
as the foundation of SunOS.  The last BSD version
released by BSD is 4.4BSD.

    BSDI (Berkeley Software Design, Inc.) a private
company founded in 1991 and headquartered in Falls
Church, VA, continues to develop BSD code.  In
1993, BSDI offers a complete version of BSD's NET 2
for x86 machines, which contains no USL code and
includes some GNU and other utilities.  Other
platforms are forthcoming.



Bubble Jet
Canon's ink jet printer technology.  The ink is
heated, which produces a bubble that expands and
ejects the ink out of the nozzle.  As the bubble
cools, the vacuum created draws fresh ink back into
the nozzle.


BUBJET.WMF

The Bubble Jet Technology
The technology is quite amazing.  The heated ink
creates a bubble that forces the ink out of the
nozzle.  As the bubble cools down, the vacuum that
it creates draws fresh ink back into the nozzle.
(Diagram courtesy of CalComp, Inc.)





C
A high-level programming language developed at Bell
Labs that is able to manipulate the computer at a
low level like assembly language.  During the last
half of the 1980s, C has become the language of
choice for developing commercial software.

    C can be compiled into machine languages for
almost all computers.  For example, UNIX is written
in C and runs in a wide variety of micros, minis
and mainframes.

    C is programmed as a series of functions that
call each other for processing.  Even the body of
the program is a function named "main."  Functions
are very flexible, allowing programmers to choose
from the standard library that comes with the
compiler, to use third party functions from other C
suppliers, or to develop their own.

    Compared to other high-level programming
languages, C appears complicated.  Its intricate
appearance is due to its extreme flexibility.  C
was standardized by ANSI (X3J11 committee) and ISO
in 1989.  See Turbo C, Borland C++, Microsoft C and
Visual C++.


    The following C example converts fahrenheit to
centigrade:

     main()   {
     float fahr;
     printf("Enter Fahrenheit ");
     scanf("%f", &fahr);
     printf("Celsius is %f\n", (fahr-32)*5/9);
              }


    A C example used to create the DOS version of
this database follows the next paragraph.


The Origin of C
C was developed to allow UNIX to run on a variety
of computers.  After Bell Labs' Ken Thompson and
Dennis Ritchie created UNIX and got it running on
several PDP computers, they wanted a way to easily
port it to other machines without having to rewrite
it from scratch.  Thompson created a language
called B, a simpler version of a language called
BCPL, itself a version of CPL.  Later, in order to
improve B, Thompson and Ritchie created C.





cache
Pronounced "cash."  A dedicated bank of high-speed
memory or a reserved section of regular memory used
to improve performance.  The cache provides a
temporary storage area for instructions and data
that is closer to the CPU's speed.  The larger the
cache, the faster the performance, since there is a
greater chance that the instruction or data
required next is already in the cache.

CACHEMEM.WMF


Memory Caches
A memory cache, or CPU cache, is a memory bank that
bridges main memory and the CPU.  It is faster than
main memory and allows instructions to be excecuted
and data to be read at higher speed.  Instructions
and data are transferred to the cache in blocks,
using some kind of look-ahead algorithm.  The more
sequential the instructions and data, the more the
cache improves performance.

    A level 1 (L1) cache is a memory bank built into
or packaged within the chip.  A level 2 cache (L2)
is a group of memory chips on the motherboard.
Increasing a Level 2 cache may speed up some
applications and amount to nothing on others.  Both
types are used together.  In PCs, the cache is
static RAM (SRAM), while main memory is dynamic RAM
(DRAM).

CACHDISK.WMF


Disk Caches
A disk cache is a section of main memory or memory
on the controller board that bridges the disk and
the CPU.  When the disk is read, a larger block of
data is copied into the cache.  If subsequent
requests for data can be satisfied in the cache, a
much slower disk access is not required.

    If the cache is used for writing, data is queued
up at high speed and then written to disk during
idle machine cycles by the caching program.  If the
cache is built into the hardware, the disk
controller figures out when to do it.

    DOS and Windows 3.x use the SmartDrive caching
program.  Windows 95 uses Vcache.  See write back
cache and write through cache.





Cairo
The code name for an object-oriented version of
Windows NT to be released in 1997.  It is expected
to support both 32- and 64-bit CPUs and initially
be available for Digital's Alpha family, which is a
64-bit platform.  Digital is expected to develop
the compilers for Cairo.

 In the full version of this software, code
 names for upcoming software packages are
 included.  Once coined, code names linger for
 a long time and sometimes even become the
 trade name of the product.





camera ready
Printed material that serves as original artwork
for commercial printing.  Camera-ready material is
photographed, and the films are made into plates
for the printing presses.  Camera ready implies
high-resolution text and graphics.  See resolution
and high-resolution.



card
See expansion board, printed circuit board,
magnetic stripe, punched card and HyperCard.


CARD.WMF





Category 3, 5, etc.
See cable categories.



CATIA
A family of 2-D and 3-D CAD programs from IBM.
CATIA was one of the first CAD programs to provide
3-D solid modelling.  The program was developed by
Dassault Aviation, a French aerospace company.
CATIA runs on IBM mainframes, RS/6000 and HP 9000
workstations with other platforms expected in the
future.

 In the full version of this software, all
 important software packages are described.





CCIE
(Cisco Certified Internetwork Expert)  A
certification for competency in internetworking
devices and concepts and Cisco routers
specifically.  It is administered by Cisco Systems,
San Jose, CA, as well as Drake testing centers
throughout the U.S. and Canada.



CD caddy
A plastic container that a CD-ROM disc is placed
into for use in a caddy drive.  The caddy is
inserted into the disc drive.  A caddy is not a
jewel case.  A jewel case protects the disc for
transportation.  A caddy protects the disc while
reading and writing.


CDROM.WMF

Caddyless and Caddy Drives
Earlier CD-ROM drives used a caddy.  Today, most
CD-ROM drives use a tray; however, CD-R
drives may require caddies.





CD-ROM XA
(CD-ROM eXtended Architecture)  A CD-ROM
enhancement introduced in 1988 by Philips, Sony and
Microsoft that lets text and pictures be narrated
by allowing concurrent audio and video.  It
provides up to 9.5 hours of AM-quality stereo or 19
hours of monophonic audio.  CD-ROM XA drives are
required for Kodak's Photo CD discs.

    CD-ROM XA functions as a bridge between CD-ROM
and CD-I, since CD-ROM XA discs will play on a CD-I
player.  CD-ROM XA uses a standard CD-ROM player,
but requires a CD-ROM XA controller card in the
computer.  See CD-I and DVI.



CDMA
(Code Division Multiple Access)  A spread spectrum
technique that converts analog signals into digital
for transmission over the cellular network.  It
provides up to 35 times the capacity of the analog
network.  Qualcomm, Inc., San Diego, CA, has
several patents on products using its CDMA
implementation.  See FDMA, TDMA and CDPD.



CeBIT
The world's largest information technology show
hosted in Hannover, Germany.  In 1994, 3570
exhibitors from Germany and 2,280 exhibitors from
53 other countries drew 675,000 attendees.  The
1995 schedule is March 8-15.

 In the full version of this software, all the
 major trade shows are included with their
 current schedule.





certification
See CCP, NetWare certification, Microsoft Certified
Professional, CompTIA and CCIE.



Character Map
A Windows utility that displays all the characters
in a particular font.  See Win 3.1 Typing special
characters and Win 95 Typing special characters.



CICS programmer
A programmer versed in CICS commands as well as in
the programming language used to develop the
application.  See CICS.



CIO
(Chief Information Officer)  The executive officer
in charge of all information processing in an
organization.  The CIO's job is a demanding one and
one that may not receive the same praise and
rewards as other executives.  Information systems
in an organization is often taken for granted until
something breaks down, which is when the CIO
catches hell.

    The CIO is responsible for explaining to
executive managment the complex nightmare this
industry has gotten itself into over the past 30
years and why equipment must be constantly
retrofitted or replaced.  Justifying new
expenditures can be the most difficult part of the
job.  See salary survey.

 The full version of the software contains the
 lastest salary survey from Source Edp.  It
 shows what computer professionals earn, where
 they earn it and what each job entails.





client/server
An architecture in which the client (personal
computer or workstation) is the requesting machine
and the server is the supplying machine, both of
which are connected via a local area network (LAN)
or wide area network (WAN).  Servers can be high-
speed microcomputers, minicomputers or even
mainframes.  The client contains the user interface
and may perform some or all of the application
processing.

    A database server maintains the databases and
processes requests from the client to extract data
from or update the database.  An application server
provides additional business processing for the
clients.

    The term client/server is sometimes used to
contrast a peer-to-peer network, in which any
client can also act as a server.  In that case,
client/server means nothing more than having a
dedicated server.

    However, client/server architecture really means
much more than dedicated servers.  Simply
downloading files from or sharing programs and
databases on a server is not true client/server
either.  True client/server implies that the
application is designed from the start to run on a
network and that the network infrastructure
provides the same quality of service as traditional
mini and mainframe information systems.

    The network operating system (NOS) together with
the database management system (DBMS) and
transaction monitor (TP monitor) are responsible
for integrity and security.  The more robust these
components, the more successful the application
that is deployed on LANs of clients and servers.


^NON-CLIENT/SERVER
In non-client/server architecture, the server is
nothing more than a remote disk drive.  The user's
machine does all the processing.  If many users
routinely perform lengthy searches, this can bog
down the network, because each client has to pass
the entire database over the net.  At 1,000 bytes
per record, a 10,000 record database requires 10MB
of data be transmitted.

CS_NONE.WMF


^TWO-TIER CLIENT/SERVER
Two-tier client/server is really the foundation of
client/server.  The database processing is done in
the server.  An SQL request is generated in the
client and transmitted to the server.  The DBMS
searches locally and returns only matching records.
If 50 records met the criteria, only 50K would be
transmitted.  This reduces traffic in the LAN.

CS_2.WMF

 In the full version of this software,
 three-tier client/server is diagrammed and
 explained along with a list and explanation
 of the popular client/server development
 systems. 





cluster
Some number of disk sectors that are treated as a
unit.  The entire disk is divided into clusters,
each one a minimum unit of storage.  Thus, on
large-capacity disks, small files waste alot of
space.  For example, in DOS, a 30-byte file will
use at least 2,048 bytes (four 512-byte sectors).
See lost cluster.

    Following are the cluster sizes that DOS uses
starting with DOS 4.0.  The disk size is the
partition size.  One physical hard disk may have
multiple partitions; for example, C: and D: could
be on the same hard disk.

         Disk Size    Cluster Size
        0 -  127MB        2K
      128 -  255MB        4K
      256 -  511MB        8K
      512 - 1023MB       16K
     1024 - 2047MB       32K





CMOS setup
See hard disk configuration.



code generator
See application generator and macro recorder.



codec
(1) (COmpressor/DECompressor)  A hardware circuit
or software routine (software codec) used to
compress and decompress digitized audio, video or
images.  Most codecs include the functions of A/D
and D/A conversion as well as compression and
decompression.  See video codec.

(2) (COder-DECoder)  A hardware circuit that
converts analog audio or video signals into digital
code, and vice versa, using techniques such as
pulse code modulation and delta modulation.  A
codec is an A/D and D/A converter.





COLD
(Computer Output to LaserDisc)  Archiving large
volumes of transactions on optical media.  Instead
of printing large paper reports or producing
microfilm or microfiche, data is stored on optical
disks.  The advantage of COLD over COM (Computer
Output Microfilm) for high-volume, archival storage
is that optical disks can be directly accessed just
like a hard disk.



cold boot
Starting the computer by turning power on.  Turning
power off and then back on again clears memory and
many internal settings.  Some program failures will
lock up the computer and require a cold boot to use
the computer again.  In other cases, only a warm
boot is required.  See boot, warm boot and clean
boot.



collapsed backbone
A network configuration that provides a backbone in
a centralized location, to which all subnetworks
are attached.  A collapsed backbone is implemented
in a router or switch that uses a high-speed
backplane that can handle the simultaneous traffic
of all or most all of its ports at full wire speed.


ROUTER.WMF





color depth
Same as bit depth.



color model
The method used to represent color for display and
printing.  See RGB, CIE, CMYK, HSV, HLS and YIQ.



COMDEX

 In the full version of this software, the
 annual schedules of upcoming major computer
 shows are included.





comma delimited
A record layout that separates data fields with a
comma and usually surrounds character data with
quotes, for example:

 "Pat Smith","5 Main St.","New Hope","PA","18950"
 "K. Jones","34 E. 88 Ave.","Syosset","NY","10024"





component software
Software routines that are designed to work
together and cooperate with each other.  For years,
this has been a dream of the software community,
but it is slowly materializing.  Object technology
has formalized the building of self-contained
program modules that interact with each other.  In
time, more and more programs may be built by
combining components.

    In addition, the industry is moving towards
document-centric processing in which a compound
document contains text, images and video.  It
requires that different applications can be called
on instantly to work on each piece of the document
with no more effort than moving the cursor to the
appropriate data structure that is on screen.

    In many cases, users do not really need full-
blown applications to do simple tasks such as text
editing and spreadsheet computations.  It is
expected that smaller software components that
provide a handful of functions may eventually
replace the monster applications that do
everything.  Through transport mechanisms such as
OpenDoc, CORBA and OLE, it is hoped that these
components can seamlessly interoperate in a
heterogeneous environment.  See OpenDoc, CORBA and
OLE.





computer
A general-purpose machine that processes data
according to a set of instructions that are stored
internally either temporarily or permanently.  The
computer and all equipment attached to it are
called hardware.  The instructions that tell it
what to do are called software.  A set of
instructions that perform a particular task is
called a program, or software program.


WHAT A COMPUTER DOES
The instructions in the program direct the computer
to input, process and output as follows:


Input/Output
The computer can selectively retrieve data into its
main memory (RAM) from any peripheral device
(terminal, disk, tape, etc.) connected to it.
After processing the data internally, the computer
can send a copy of the results from its memory out
to any peripheral device.  The more memory it has,
the more programs and data it can work with at the
same time.


Storage
By outputting data onto a magnetic disk or tape,
the computer is able to store data permanently and
retrieve it when required.  A system's size is
based on how much disk storage it has.  The more
disk, the more data is immediately available.



PROCESSING
(The 3 C's*)
Once the data is in the computer's memory, the
computer can process it by calculating, comparing
and copying it.


Calculate
The computer can perform any mathematical operation
on data by adding, subtracting, multiplying and
dividing one set with another.


Compare
The computer can analyze and evaluate data by
matching it with sets of known data that are
included in the program or called in from storage.


Copy
The computer can move data around to create any
kind of report or listing in any order.

    By calculating, comparing and copying, the
computer accomplishes all forms of data processing.
For example, records are sorted into a new order by
comparing two records at a time and copying the
record with the lower value in front of the one
with the higher value.

    The computer finds one customer out of thousands
by comparing the requested account number to each
record in the file.  The dBASE query statement:
SUM SALARY FOR TITLE = "NURSE" causes the computer
to compare the title field in each record for NURSE
and then add (calculate) the salary field for each
match.

    In word processing, inserting and deleting text
is accomplished by copying characters from one
place to another.


Remember The 3 C's
If you wonder whether the computer can solve a
problem, identify your data on paper.  If it can be
calculated, compared and copied on paper, it can be
processed in the computer.



3CS1.WMF

The 3 C's - Finding Things
The example above counts all California records in
the database by comparing each record with "CA."
Every record in the database is read into memory.
The memory locations that state is written into
are compared with the letters "CA" in the program.
If they are equal, a "1" is added to the
California counter.  The second record is written
into the same memory bytes as the first record,
and the field is compared again.  This process is
performed until the last record has been examined.



3CS2.WMF

The 3 C's - Displaying and Printing
Data is stored as contiguous fields in the
database.  There are no blanks in between.  The
data is displayed and printed the way we like to
see it by writing the data into memory and copying
the characters into the desired order.  The date
in this example is printed through a "picture,"
which is a set of characters that acts as a
filter.  Each character in the date is compared to
a corresponding character in the picture, and the
one copied as output is determined by the rules.
Pictures can be implemented in software or in
hardware.

 In the full version of this software, there
 is more information on how computers
 calculate, compare and copy.  An overview
 of the different generations and types of
 computers is also provided.

 Fundamental components, such as computer,
 operating system and database management
 system (DBMS) are explained in depth like
 a textbook.





computer books
See how to find a good computer book.



concurrency
Simultaneous operation within the computer.  See
multiprocessing, multitasking, multithreading, SMP
and MPP.



CONFIG.SYS
A DOS and OS/2 configuration file.  It resides in
the root directory and is used to load drivers and
change settings at startup.  Install programs often
modify CONFIG.SYS in order to customize the
computer for their particular use.  Windows 95
executes the lines in CONFIG.SYS if it contains
drivers that Windows 95 found no counterpart for
when it was installed.  See DOS CONFIG.SYS.

 In the full version of the software, all the
 important DOS commands are described with
 syntax examples.





conventional memory
In a PC, the first 640K of memory.  The next 384K
is called the UMA (upper memory area).  The term
may also refer to the entire first megabyte (1024K)
of RAM, which is the memory that DOS can directly
manage without the use of additional memory
managers.  See DOS memory manager.



CORBA
(Common Object Request Broker Architecture)  A
standard from The Object Management Group (OMG) for
communicating between distributed objects.  The
concept behind CORBA is to provide a standard way
to execute program modules in a distributed
environment no matter what language the routines
are written in or what platform they reside in.  It
enables complex systems to be built across an
entire enterprise.  For example, three-tier
client/server applications can be constructed using
CORBA-compliant ORBs.  CORBA is suited for widely
disbursed networks, where an event occurring in one
location requires services to be performed in
another.

 In the full version of this software, the
 CORBA entry contains more information.  In
 addition, other distributed processing
 environments such as Microsoft's DCOM and
 The Open Group's DCE are also included.





cross tabulate
To analyze and summarize data.  A common example is
summarizing the details from database records and
placing them into a spreadsheet.  The following
example places the details of order records into
summary form.

     Transactions being cross tabbed
     Date      Customer    Quantity
     1- 7-93   Smith           7
     1-13-93   Jones          12
     2- 5-93   Gonzales        4
     2-11-93   Fetzer          6
     3-10-93   Smith          12
     3-22-93   Gonzales       15


     Results of cross tab
     Customer   Jan   Feb   Mar   Total
     Smith        7          12      19
     Jones       12                  12
     Gonzales           4    15      19
     Fetzer             6             6

     Total       19    10    27      56





cryptography
The conversion of data into a secret code for
transmission over a public network.  The original
text, or plaintext, is converted into a coded
equivalent called ciphertext via an encryption
algorithm.  The ciphertext is decoded (decrypted)
at the receiving end and turned back into
plaintext.

    The encryption algorithm uses a key, which is a
binary number that is typically from 40 to 128 bits
in length.  The data is "locked" for sending by
combining the bits in the key mathematically with
the data bits.  At the receiving end, the key is
used to "unlock" the code, restoring it to its
original binary form.

Secret versus Public Key
There are two cryptographic methods.  The
traditional method uses a secret key, such as the
DES standard.  Both sender and receiver use the
same key to encrypt and decrypt.  This is the
fastest method, but transmitting the secret key to
the recipient in the first place is not secure.

    The second method is public-key cryptography,
such as RSA, which uses both a private and a public
key.  Each recipient has a private key that is kept
secret and a public key that is published for
everyone.  The sender looks up the recipient's
public key and uses it to encrypt the message.  The
recipient uses the private key to decrypt the
message.  Owners never have a need to transmit
their private keys to anyone in order to have their
messages decrypted, thus the private keys are not
in transit and are not vulnerable.

    Sometimes, both DES and RSA are used together.
DES provides the fastest decryption, and RSA
provides a convenient method for transmitting the
secret key.  Both the DES-encrypted text message
and the secret key needed to decrypt it are sent
via the RSA method.  This is called a digital
envelope.

    Cryptography methods change as computers get
faster.  It has been said that any encryption code
can be broken given enough computer time to derive
all of the permutations.  However, if it takes
months to break a code, the war could be won or
lost, or the financial transaction has little
meaning.  As computers get faster, the keys get
longer and the algorithms become more complex to
stay ahead of the game.  See DES, RSA, digital
signature and digital certificate.


ENCRYPT.WMF

Secret Key vs Public Key
The secret method uses the same key to encrypt and
decrypt.  The problem is transmitting the key to
the recipient in order to use it.  The public key
method uses two keys.  One kept secret and never
transmitted, and the other made public.  Sometimes
the public key method is used to safely send the
secret key to the recipient so that the message
can be encrypted using the faster secret key
algorithm.





Cu-Cme
See CU-SeeMe.



CyberCash
A system of digital money from CyberCash, Inc.  For
credit card purchases, the merchant sends customers
electronic invoices.  Customers append their credit
card numbers to the invoices which are encrypted
via CyberCash software and sent back to the
merchant.  The merchants append their ID numbers to
the invoices, encrypt them and send them to a
CyberCash server for forwarding to the banking
network.

    Debit and cash transactions are handled by pre-
establishing accounts with and making deposits into
a participating bank.  Encrypted messages are sent
to the merchant to enable the funds transfer.  See
digital money.



daemon
Pronounced "demon."  A UNIX program that executes
in the background ready to perform an operation
when required.  It is usually an unattended process
initiated at startup.  Typical daemons are print
spoolers and e-mail handlers or a scheduler that
starts up another process at a designated time.
The term comes from Greek mythology meaning
"guardian spirit."  Same as agent.



data administrator
A person who coordinates activities within the data
administration department.  Contrast with database
administrator.


SYSDEVC.WMF

 The full version of the software contains
 the lastest salary survey from Source Edp.
 It shows what computer professionals earn,
 where they earn it and what each job entails.





data communications equipment
See DCE.



data compression
Encoding data to take up less storage space.
Digital data is compressed by finding repeatable
patterns of binary 0s and 1s.  The more patterns
can be found, the more the data can be compressed.
Text can generally be compressed to about 40% of
its original size, and graphics files from 20% to
90%.  Some files compress very little.  It depends
entirely on the type of file and compression
algorithm used.

    There are numerous compression methods in use.
Two major technologies are Huffman coding and
Lempel-Ziv-Welch (LZW), representing examples of
the statistical and dictionary compression methods.

    When a compression algorithm is packaged for use
for a specific platform and file format, it is
called a codec (compressor/decompressor).  ADPCM,
PCM and GSM are examples of codecs for sound, and
Indeo, Cinepak and MPEG are examples of codecs for
video.

    In the DOS/Windows world, Pkzip is the most
widely-used compression application.  See Pkzip
abc's.


Lossless versus Lossy
When text and financial data are compressed, they
must be decompressed back to a perfect original,
bit for bit.  This is known as lossless
compression.  However, audio and video can be
compressed to as little as 5% of its original size
using lossy compression.  Some of the data is
actually lost, but the loss is not noticeable to
the human ear and eye.


LOSSY.WMF





data encryption
See cryptography.



data entry program
An application program that accepts data from the
keyboard or other input device and stores it in the
computer.  It may be part of an application that
also provides updating, querying and reporting.

    The data entry program establishes the data in
the database and should test for all possible input
errors.  See validity checking, table lookup, check
digit and intelligent database.



database administrator
A person responsible for the physical design and
management of the database and for the evaluation,
selection and implementation of the DBMS.

    In most organizations, the database
administrator and data administrator are one in the
same; however, when the two responsibilities are
managed separately, the database administrator's
function is more technical.  See salary survey.

 The full version of the software contains
 the lastest salary survey from Source Edp.
 It shows what computer professionals earn,
 where they earn it and what each job entails.





de facto standard
A widely-used format or language not endorsed by a
standards organization.



de jure standard
A format or language endorsed by a standards
organization.



decision support system
See DSS, EIS and OLAP.



development tool
Software that assists in the creation of new
software.  Compilers, debuggers, visual programming
tools, GUI builders, application generators are
examples.  See developer's toolkit.  For a list of
popular client/server development tools, see
client/server development system.



DIF
(1) (Data Interchange Format)  A standard file
format for spreadsheet and other data structured in
row and column form.  Originally developed for
VisiCalc, DIF is now under Lotus' jurisdiction.

(2) (Display Information Facility)  An IBM
System/38 program that lets users build custom
programs for online access to data.

(3) (Document Interchange Format)  A file standard
developed by the U.S. Navy in 1982.

(4) (Dual In-line Flatpack)  A type of surface
mount DIP with pins extending horizontally outward.



digital certificate
The digital equivalent to an ID card in the RSA
public key encryption system.  Digital certificates
are issued by certification organizations such as
VeriSign, Inc., Mountain View, CA, after verifying
that a public key belongs to a certain owner.

    The digital certificate is sent along with an
encrypted message to verify that the sender is
truly the entity identifying itself on the
transmission.  The public key of the certifying
organization is widely publicized so that its
digital signature can be decrypted.  The digital
certificate contains the following data:

   owner name, company and address
   owner public key
   owner certificate serial number
   owner validity dates
   certifying company ID
   certifying company digital signature





digital money
Electronic money used on the Internet.  In order to
turn the Internet into a giant cybermall (online
shopping center), companies have developed software
that provides complete and secure order fulfillment
over the Internet.  These software packages support
a variety of payment schemes, which mostly fall
into two categories.

    The first category is the traditional credit
card.  Most Web browsers and Internet Service
Providers (ISPs) support one of the major security
protocols such as Secure Socket Layer (SSL).  For
example, on NetScape's browser, if the transmission
between browser and server is secure, the key icon
at the lower left side of the screen is connected.
Otherwise, it is split in half to signal an
unsecure transmission.  More elaborate methods,
such as CyberCash's credit card system, prevent the
merchant from seeing the credit card number.

    The second type of digital money is like
travelers checks and is being implemented and
tested by several companies such as DigiCash
(ecash) and CyberCash.  This digital money is
either downloaded as "digital coins" from a
participating bank into the user's personal
computer or a digital money account is set up
within the bank.  Either the digital coins or the
transactions that debit the account are transmitted
to the merchant for payment.  All of these
transactions are encrypted for security.

    Many believe that if the cost for processing
digital money can be kept down, it will fuel an
entirely new online information industry that
allows customers to pay for exactly what they use.
For example, 5 cents for each information lookup or
10 cents for each applet download, perhaps even a
fraction of a cent for certain transactions.  Time
will tell if the economics allow for this scenario.

    In the meantime, although trillions of dollars
are routinely transferred around the world via the
private banking network, money traversing the
public Internet would seem like easy pickings for
the dishonest hacker.  As with any new system,
time, along with a few panics, will bring about the
confidence necessary for everyday use.  Surprises
are definitely expected.  See ecash, CyberCash,
First Virtual, OMI and cybermall.





digital signature
An electronic signature that cannot be forged.  It
is a coded message that accompanies the text
message transmitted over a network.  Digital
signatures are typically implemented using the de
facto standard RSA public key cryptography method.

    To send a digital signature, the sender uses an
algorithm to compute a hash value from his or her
text message.  Using the sender's private key, the
sender encrypts the hash value, turning it into a
message digest.  The text message is then encrypted
with the private key, and both message and message
digest are transmitted to the recipient.  The
recipient uses the sender's public key to decrypt
the message and message digest.  Using the same
hashing algorithm, a new message digest is computed
from the text message and compared with the message
digest that accompanied it.  If they match, the
signature is authenticated.

Signatures and Certificates
A digital signature ensures that the document
originated with the person signing it and that it
was not tampered with after the signature was
applied.  However, the sender could still be an
impersonator and not the person he or she claims to
be.  To verify that the message was indeed sent by
the person claiming to send it requires a digital
certificate, which is issued by a certification
authority.  See digital certificate.


DIGSIG.WMF





DIN connector
(Deutsches Institut fur Normung - German Standards
Institute)  A plug and socket used to connect a
variety of devices; for example, the PC keyboard
uses a five-pin DIN.  Full-size DIN plugs look like
an open metal can a half inch in diameter with pins
inside in a circular pattern.  The smaller Mini-DIN
plugs have a 5/16ths of an inch diameter.


DIN.WMF

DIN Connectors
DIN connectors are commonly used for keyboard and
mouse ports on desktop and laptop computers.


 In the full version of this software, all the
 important plugs, sockets and connectors are
 explained and diagrammed such as this one.





DIP
(1) (Dual In-line Package)  A common rectangular
chip housing with leads (pins) on both long sides.
Tiny wires bond the chip to metal leads that wind
their way down into spider-like feet that are
inserted into a socket or are soldered onto the
board.


DIP.WMF

The DIP
The DIP chip package is commonly used to hold
small chips, such as main memory, cache memory,
A/D and D/A converters.  PGA packages are another
type of packaging commonly used to hold larger
chips, such as high-end CPUs.





DIP switch
(Dual In-line Package switch)  A set of tiny toggle
switches built into a DIP, which is mounted
directly on a circuit board.  The tip of a pen or
pencil is required to flip the switch on or off.

    Remember!  Open is "off."  Closed is "on."

DIPSWTCH.WMF

Switches on the DIP
DIP switches provide an inexpensive way to select
options on a hardware device and will probably be
used for years to come.  However, as personal
computers become more sophisticated, plug-in
boards increasingly contain programmable chips.
 Instead of opening the case, pulling the
board and figuring out which switch to flip,
settings are changed using a software
control panel.





Dir
(DIRectory)  A CP/M, DOS and OS/2 command that
lists the file names on the disk.  See DOS Dir.



direct access storage device
See DASD.



direct memory access
See DMA.



DirectDraw
A 2-D graphics programming interface (API) from
Microsoft for Windows 95 and NT.  DirectDraw
provides low-level access to the frame buffer and
advanced features of the display adapter.  See
video accelerator and Direct3D.



discussion thread
See threaded discussion.



disk cache
See cache.

 Here's a perfect hypertext example.  Click
 on cache either in this sentence or above,
 and you will jump to its entry.

 Then click the REVIEW button to come back
 to this entry... that is provided you looked
 up "disk cache" rather than just found it by
 scrolling the text.





display adapter
An expansion board that plugs into a desktop
computer that converts the images created in the
computer to the electronic signals required by the
monitor.  It determines the maximum resolution,
maximum refresh rate and the number of colors that
can be sent to the monitor.  The monitor must be
equally capable of handling its highest resolution
and refresh.  The VGA card is the common display
adapter for the PC.

    The display adapter converts the characters or
graphic patterns (bitmaps) within the computer's
memory into signals used to refresh the display
screen.  Display adapters also contain their own
memory, which is used to build the images before
they are displayed.

    In earlier digital systems (CGA, EGA, etc.), the
display adapters generated digital signals for the
monitor.  The monitor then did the conversion from
digital to analog.  In today's analog systems (VGA,
Macintosh, etc.), the display adapter creates the
analog signals that are sent to the monitor.

It's Real Straightforward
Graphics adapter, graphics board, graphics card,
graphics controller, video display adapter, video
display board, video display card, video display
controller, video adapter, video board, video card,
video controller, display board, display card,
display controller, VGA adapter, VGA board, VGA
card and VGA controller are other terms for the
display adapter.

    By the way, a video graphics board is something
different.  It is a video capture board that
accepts analog NTSC video from a videotape player
(VCR) or camera.  Increasingly, NTSC video is being
integrated with computers, so the terminology might
even get a tad more confusing!

 We don't just tell you the correct "computer
 science" term for something-- we tell how the
 words are used day in and day out-- right,
 wrong and indifferent.

 People make up this industry, and say the same
 thing in different ways.

 You need to know them all.





display resolution
See how to select a PC display system.



DOS Cd
An internal command that changes the current
directory.  Chdir is an alternate form.  To change
to the DATA directory type:

     C:\ANYWHERE>cd \data

         or type:

     C:\ANYWHERE>chdir \data


 The syntax for more than 150 DOS commands is
 included in the full version of this software.





e-commerce
See electronic commerce.



Easter Egg
An undocumented function hidden in a program.
Easter Eggs are secret "goodies" that are found by
accident or word of mouth.  For example, in Windows
3.1, to see the names of the people who worked on
the project, open the About Program Manager dialog
box (Help, About) and double click on the Windows
icon at the upper left while holding down Ctrl and
Shift.  Click OK, then open the box again.  Ctrl-
Shift Double click again and note the dedication.
Click OK and repeat once more.





echo
(1) A repetition of a signal in a communications
line.  The difference in electrical characteristics
at opposite ends can cause the echo.

(2) In communications, to transmit received data
back to the sending station allowing the user to
visually inspect what was received.  A local echo
displays what you type on your screen.

(3) A DOS and OS/2 screen command that displays
messages and turns off/on screen responses.  See
DOS batch file.



EISA
(Extended ISA)  Pronounced "ee-suh."  A PC bus
standard that extends the 16-bit ISA bus (AT bus)
to 32 bits and provides bus mastering.  ISA cards
can plug into an EISA slot.  It was announced in
1988 as a 32-bit alternative to the Micro Channel
that would preserve investment in existing boards.
EISA is also used in various workstations from HP
and others.

    EISA still runs at the slow 8MHz speed of the
ISA bus in order to accommodate all the ISA cards
that may be plugged into it.  PCI and VL-bus local
buses provide independent data paths and higher
speeds than EISA.


CARDS.WMF

Types of Expansion Boards 
There are five major types of expansion boards
that plug into a PC's bus, the ISA board being the
most ubiquitous.  EISA is often
used in high-end servers, and IBM's Micro Channel
is primarily found in older PS/2s.
Pentium systems generally have a combination of
ISA and PCI slots or EISA and PCI slots.





embedded SQL
SQL statements that are written into a high-level
programming language such as C or Pascal.  In a
preprocessing stage, the SQL code is converted into
function calls, which may be optimized to provide
the fastest results.  If the programmer knows
exactly what the query is going to do, and the
query does not change, it is called static SQL.  If
the query requires user input at runtime, it is
called dynamic SQL.  If the client program passes
the SQL statements directly to the database server
without any intermediate step, it is called
passthrough SQL.



emoticon
(EMOTional ICON)  Also called a smiley, it is an
expression of emotion typed into a message using
standard keyboard characters.  The following
examples are viewed sideways.  Tilt your head down
toward your left shoulder.


   Smiley   Meaning
   :)       original smiley face

   :-)      smile

   :-(      frown

   ;-)      wink

   :-D      big smile

   :-O      mouth open in amazement

   :-Q      tongue hanging out in nausea

   :-{)     smile (user has moustache)

   :-{)}    moustache and beard

   8-)      smile (user wears glasses)

   (-:      smile (user left handed or Australian)

   :*)      red nosed smile, suggesting inebriation

   *<|:{)}  Santa Claus!

   @:{)===  sikh with turban and long beard


    For an extensive list of more than 650
emoticons, read "Smileys" by David Sanderson,
published by O'Reilly & Associates, Inc., ISBN 1-
56592-041-4.


EMOTICON.WMF

Santa Claus via an Emoticon
You turn your head down to the left in order to
interpret an emoticon.





Ethernet hub
A device that all lines on an Ethernet segment are
plugged into.  10BaseT and 100BaseT Ethernets are
star networks and require a hub for operation.  The
earlier 10Base5 and 10Base2 Ethernets are bus
networks, but are often wired into a star
configuration using a central hub for improved
troubleshooting.  A hub is also known as a
multiport repeater and is sometimes called a
concentrator.  See hub.



Ethernet switch
See switched Ethernet.



Exception error 12
A DOS error message that means DOS does not have
enough room to handle hardware interrupts.
Increase the number of stacks in the STACKS=
command in the CONFIG.SYS file (see DOS Stacks).



exponent
The number written above the line and to the right
of a number that indicates the power of a number,
or how many zeros there are in it.  For example 10
to the 3rd power indicates three zeros.  The number
467,000 can be stated as 467 x 10 to the 3rd.  On a
screen or printout, the number is expressed as
467E3.  See floating point.



extension
A DOS, Windows and OS/2 file category.  Extensions
are file types, or file categories, that are added
to the end of DOS, Windows 95 and OS/2 file names.
The extension is separated from the file name with
a dot such as LETTER.DOC.

    An extension can have up to three letters or
digits.  Executable files use .EXE, .COM and .BAT
extensions; for example, NOTEPAD.EXE is the text
editor that comes with Windows.

    All programs and most data files use extensions.
However, some word processing files do not, in
which case you could create your own filing system;
for example, CHAP1.NOV and CHAP2.NOV could be
chapters in a novel.  See graphics formats.  See
also Macintosh extension.


 Ext. Type of file
 906  Calcomp plotter

 ABC  This program's master index
 AD   After Dark image
 AFM  Type 1 font metrics
 AG4  Access G4 document imaging
 AI   Adobe Illustrator graphics,
        Encapsulated PostScript header
 ARC  ARC, ARC+ compressed

 There are more than 250 extension listings
 in the full version of this software.





EZ drive
See EZ135.



fabless
(FABricationLESS)  A semiconductor vendor that does
not have inhouse manufacturing facilities.
Although it designs and tests the chips, it relies
on external foundries for their actual fabrication.
See foundry.



face recognition
The ability to recognize people by their facial
characteristics.  The most successful methods use
neural networks that learn from their experience
and can distinguish the same person with different
appearances, such as with and without glasses,
changing hair styles and seasonal skin color.


 Picture not available in demo version.

TrueFace
Miros' TrueFace face recognition system uses
neural network technology to distinguish changing
appearances.  (Photo courtesy of Miros, Inc.)





far pointer
In an Intel x86 segmented address, a memory address
that includes both segment and offset.  Contrast
with near pointer.



Fast Fourier Transform
See FFT.



fat binary
A Macintosh executable program that contains
machine language in one file for both the Macintosh
and PowerMac machines (680x0 and PowerPC CPUs).
Software distributed in this format will run native
on whichever Mac architecture it is loaded on.



FDMA
(Frequency Division Multiple Access)  The
technology used in the analog cellular telephone
network that divides the spectrum into 30KHz
channels.  See TDMA, CDMA and CDPD.



feature connector
See VGA feature connector.



Fiber Channel
See Fibre Channel.



field
A physical unit of data that is one or more bytes
in size.  A collection of fields make up a record.
A field also defines a unit of data on a source
document, screen or report.  Examples of fields are
NAME, ADDRESS, QUANTITY and AMOUNT DUE.

    The field is the common denominator between the
user and the computer.  When you interactively
query and update your database, you reference your
data by field name.

    There are several terms that refer to the same
unit of storage as a field.  A data element is the
logical definition of the field, and a data item is
the actual data stored in the field.  For each data
element, there are many fields in the database that
hold the data items.

    In the following example, for the DATA ELEMENTS
"product description" and "product no.", there are
FIELDS in the database that hold the DATA ITEMS
"manilla folder, pencil, rubber band, etc."


         DATA ELEMENTS
         Product description    Product no.
     ───┬──────────────────────┬──────────┬──
        │        FIELD         │   FIELD  │
     ───┴──────────────────────┴──────────┴──
         DATA ITEMS  manilla folder
                     pencil
                     rubber band
                     copy paper
                     paper clip
                     envelope





file compression
See data compression.



file find
A utility that searches all directories for
matching file names.  See how to find a file.



file spec
(file SPECification)  A reference to the location
of a file on a disk, which includes disk drive,
directory name and file name.  For example, in DOS,
Windows and OS/2, c:\wordstar\books\chapter is a
file spec for the file CHAPTER in the BOOKS
subdirectory in the WORDSTAR directory on drive C.



finger
A UNIX command widely used on the Internet to find
out information about a particular user, such as
telephone number, whether currently logged on or
the last time logged on.  The person being
"fingered" must have placed his or her profile on
the system.  Profiles can be very elaborate either
as a method of social introduction or to state
particular job responsibilities.  Fingering
requires entering the full user@domain address.



flame war
In an Internet newsgroup, an ongoing tirade of
contrasting opinions about a topic.



flash disk
A solid state disk made of flash memory chips.  It
emulates a standard disk drive in contrast with
flash memory cards, which require proprietary
software to make them function.  See flash memory.



flat file
A data file that is not related to or does not
contain any linkages to another file.  It is
generally used for stand-alone lists.  When files
must be related (customers to orders, vendors to
purchases, etc.), a relational database manager is
used, not a flat file manager.  Flat files can be
related, but only if the applications are
programmed to do so.

    Years ago, flat files were the very type used in
a relational database.  Before relational
databases, files were related with built-in
pointers that could not be dynamically changed.
The relational database eliminated the hardwired
linkages, resulting in "flat files."  Today, flat
files do not relate; just the opposite.  Another
example of how the terminology in this industry can
drive you nuts.

 The terminology in this field is not rigid.
 It changes with the wind.  Talk to an
 "old timer" and you may get one answer.
 Talk to a person with just a couple of years
 experience, and you'll get another.

 Wherever possible, we show you how terms
 change over time.





FLC file
An animation file format from AutoDesk, Inc.,
Sausalito, CA, that is commonly known as a "flick"
file.  It uses the .FLC file extension and provides
a 640x480 resolution.  An earlier .FLI format
provides 320x200 resolution.  Both FLC and FLI
files provide animated sequences, but not sound.
FLI and FLC formats were introduced respectively
with Autodesk's Animator and Animator Pro programs
for DOS.



Floptical
A type of floppy disk that records data
magnetically, but uses grooves in the disk to
optically align the head over the tracks.  The
original 3.5" drive from Insite Peripherals, San
Jose, CA, reads and writes 21MB Floptical and
standard 1.44MB diskettes.  The Floptical never
caught on, because it didn't offer enough
additional capacity.  However, a 120MB version of
this technology was developed by 3M and introduced
in 1996 as the LS-120.  See LS-120.

 What's true one day is not true the next.

 We stay on top of this industry and update
 this database quarterly.  After your intial
 purchase, you can subscribe quarterly for
 only $59 a year.





for statement
A high-level programming language structure that
repeats a series of instructions a specified number
of times.  It creates a loop that includes its own
control information.  The following BASIC and C
examples print "Hello" 10 times:

  BASIC               C
  for x = 1 to 10     for (x = 0;  x < 10;  x++)
   print "hello"       printf ("hello\n");
  next x





foreign key
In relational database, it is a field in one table
that is indexed in another.  Foreign keys provide
the building blocks for relating tables.  For
example, in a customer order table, the salesperson
field might contain an employee number.  That field
would be a foreign key in the table, because the
employee table would be indexed on employee number.


    CUSTOMER ORDER TABLE
    order no.  (primary key)
    salesperson (foreign key) ─┐
    etc.                       │
                               │
            ┌──────────────────┘
            │ EMPLOYEE TABLE
            └ employee no. (primary key)
              employee name
              etc.





Forest & Trees
A data analysis program for Windows from Platinum
Technology, Inc., Oakbrook Terrace, IL, that
integrates data from a variety of applications.  It
provides a control room interface that lets users
monitor important business information.



frequency division multiplexing
See FDM.



FTP
(File Transfer Protocol/File Transfer Program)  In
a TCP/IP network (Internet, UNIX, etc.), a set of
commands used to log onto the network, list
directories and copy files.  It can also convert
between the ASCII and EBCDIC character codes.  FTP
programs are designed to handle all types of files.
Unlike e-mail programs where graphics and program
files have to be "attached," FTP is designed to
handle binary files.

    The term also refers to a program that performs
the FTP function as well as the act of running it.
For example, "let's FTP them the file."  See
anonymous FTP and TFTP.





gamma correction
An adjustment to the light intensity of a scanner,
monitor or printer.  It generally refers to the
adjustment of the brightness of a display screen in
order to compensate for a CRT's irregularity.  A
gamma correction plot is a curve, not a straight
line as is the standard brightness control.  Gamma
correction is also used to make the monitor display
images more closely in appearance with the laser
printer that creates the output.



gateway
A computer that performs protocol conversion
between different types of networks or
applications.  For example, a gateway can convert a
TCP/IP packet to a NetWare IPX packet and vice
versa, or from AppleTalk to DECnet, from SNA to
AppleTalk and so on.

    Gateways function at layer 4 and above in the
OSI model.  They perform complete conversions from
one protocol to another rather than simply support
one protocol from within another, such as IP
tunneling.  Sometimes routers can implement gateway
functions.

    An electronic mail, or messaging, gateway
converts messages between two different messaging
protocols.



LANHARDW.WMF





GDI
(Graphics Device Interface)  The graphics display
system in Microsoft Windows.  When an application
needs to display or print, it makes a call to a GDI
function and sends it the parameters for the object
that must be created.  GDI in turn "draws" the
object by sending commands to the screen and
printer drivers, which actually render the images.
See DirectX.



Gigabit Ethernet
An emerging Ethernet technology that raises
transmission speed to 1 Gbps.  It is expected to be
introduced in 1997 for backbone use.  Its ability
to integrate into existing Ethernets is a distinct
advantage.  If Gigabit Ethernet can effectively
support realtime voice and video, it will likely be
a major alternative to ATM.

 Gigabit Ethernet is not here yet, but we cover
 it, because it could be very significant to
 the networking industry.

 We cover all upcoming technologies in the
 Encyclopedia so you can prepare for them.
 What's simmering today can come to a boil
 tomorrow.





graphics accelerator
A high-performance display adapter for graphical
user interfaces that has line drawing and pixel
block move functions (bitblt) built into hardware.
For example, in Windows, such boards speed up the
display of fonts and images and provide faster
scrolling.

    Windows applications will display and scroll
faster on a slower PC with a graphics accelerator
than on a faster PC without one.  See Winmark.



graphics formats
There is a wide variety of graphics formats in use
today.  The following list contains most of them.
The formats are in order by extension name under
raster or vector category.  Some formats appear in
both categories because they can hold both raster
and vector images.


    RASTER GRAPHICS FORMATS (BITMAPS)

 AI   Adobe Illustrator
 AG4  Access G4 document imaging
 ATT  AT&T Group IV
 BMP  Windows & OS/2

 There are more than 75 graphics formats listed
 in the full version of this software.





graphics program
See paint program, drawing program, presentation
graphics, image editor and image processing.



H.324
An ITU standard for videoconferencing over analog
telephone lines (POTS) using modems.



hardware
Machinery and equipment (CPU, disks, tapes, modem,
cables, etc.).  In operation, a computer is both
hardware and software.  One is useless without the
other.  The hardware design specifies the commands
it can follow, and the instructions tell it what to
do.  See instruction set.


Hardware Is
"Storage and Transmission"
The more memory and disk storage a computer has,
the more work it can do.  The faster the memory and
disks transmit data and instructions to the CPU,
the faster it gets done.  A hardware requirement is
based on the size of the databases that will be
created and the number of users or applications
that will be served at the same time.  How much?
How fast?


Software Is
"Logic and Language"
Software deals with the details of an ever-changing
business and must process transactions in a logical
fashion.  Languages are used to program the
software.  The "logic and language" involved in
analysis and programming is generally far more
complicated than specifying a storage and
transmission requirement.





hardware companies
See hardware vendors.




hardware rankings
See hardware vendors.



hardware vendors
Following are the major hardware manufacturers in
the computer industry and their past two year's
performance.  See also software vendors.


      REVENUES FROM MAJOR HARDWARE VENDORS
                      Sales  Profit  Employees
 Year  Company           (000,000)     (000)

       Computer System Manufacturers

 1995 IBM             71,940   4,178   252
 1994                 64,052   3,021   243
 1993                 62,716  (8,101)  267
 1992                 65,096  (4,965)  308

 1995 HP              31,519   2,433   102
 1994                 24,991   1,599    98
 1993                 20,317   1,177    96
 1992                 16,427     549    93

 Financial data for the 30 largest computer
 systems, disk drive and semiconductor
 companies are present in the full version.





helical scan
A tape recording method that runs the tracks
diagonally from top to bottom in order to increase
the storage capacity.  The helical scan method is
used on VHS tapes as well as on various proprietary
half-inch and 19mm tape backup units from
StorageTek, Sony and others.


HELSCAN.WMF

Helical Scan Tracks
The helical scan method records tracks on the
diagonal, which uses up more of the tape surface
than parallel recording along the length.





HHOK
Digispeak for "ha ha only kidding."



high-density CD-ROM
See DVD.



host
A computer that acts as a source of information or
signals.  The term can refer to almost any kind of
computer, from a centralized computer that is a
host to its terminals, to a server that is host to
its clients, to a desktop PC that is host to its
peripherals.  In network architectures, a client
station (user's machine) is also considered a host,
because it is a source of information to the
network in contrast to a device such as a router or
switch that directs traffic.  See host adapter and
host name.



hot link
A predefined connection between programs so that
when information in one database or file is
changed, related information in other databases and
files are also updated.  See hypertext,
hypergraphic, compound document and OLE.



Hot topics
Following is a synopsis of the latest trends in the
computer industry.


The Information Superhighway
Due to the Clinton/Gore administration's interest
in the information superhighway, and especially due
to the distribution of Mosaic, the first Web
browser in late 1993, the Internet exploded into
the consciousness of every developed country in the
world during 1994 and 1995.  However, the Internet
was never intended to be the sum total of an
information superhighway.  It was cited merely as a
model for it.  The World Wide Web and its graphical
browsers gave the Internet point and click access
and turned it into the superhighway whether it was
ready for it or not.

    The real superhighway concept was meant to
modernize the telecommunications infrastructure in
the U.S. so that everyone has access to information
and educational materials no matter what their
station in life.  Right now, there is a monthly
service fee to get onto the Internet, and you have
to have a personal computer.  This is clearly not a
service for everyone.

    In addition, "surfing the Net" at 28,800 bps,
today's highest modem speed, is an experiment in
patience.  High-speed access is necessary to keep
up this extraordinary momentum.  The delivery of
the superhighway is now in the hands of the
telephone and cable companies, because they are
already wired into everyone's home and office and
are capable of delivering multimedia content at
high speed.  ISDN telephone access and cable modems
will make surfing the net much more viable.

    Entertainment may be as much a driving force as
information and education as video-on-demand and
all variety of interactive services converge into
this new frontier of online delivery.  With deals
made daily by cable and telephone companies, video
providers and TV networks, major companies are
positioning themselves for what they believe to be
the consumer marketplace of the future.

    One thing is certain, organizations are making
enormous investments with the hopes that they know
what mom, pop and the kids want, what they will
watch and, more to the point, what they will pay
for.  See World Wide Web.


 In the full version of this software,
 intranets, multimedia, client/server and
 downsizing, networking and object
 technologies are overviewed, since these
 are the driving forces in information
 technology today.





how to access the Web
See how to access the Internet.



how to buy a new computer
See how to select a personal computer.



how to buy a used computer
See used computers and computer exchange.



how to compress files
See Pkzip abc's.



how to find things on the Net
See Web search services and how to access the
Internet.



how to import a file
See how to transfer a file.



how to spoof your technical friend
To have a light-hearted joke with your technical
colleagues, take the highest clock rate of an Intel
CPU chip and triple or quadruple it.  Then, simply
say "did you hear about Intel's 600MHz Pentium?
They've kept it a secret, but they're shipping it
now!"  Expect a "wow" reaction, or "that's
impossible!"

    Be careful.  You have to stay on top of the
numbers.  Years ago, a 100MHz chip sounded
unbelievable.  Today, workstation chips have
already reached 400MHz speeds.  It is expected that
within a few years, we will achieve 1GHz clock
rates.  See also buffer flush and Stringy Floppy.





how to surf the Net
See how to access the Internet and Web search
services.



how to work with DOS
All the DOS command examples are listed under "DOS"
in the index; for example, DOS Copy, DOS Format,
etc.  For a complete tutorial on how DOS disks are
organized and how you interact with DOS at the
command line, see DOS abc's.



how to work with Windows
Look under "Win 3.1" and "Win 95" for a list of
Windows basics; for example, Win 95 abc's, Win 95
Clipboard, etc.



IBM
(International Business Machines Corporation,
Armonk, NY)  The world's largest computer company.
It started in New York in 1911 when the Computing-
Tabulating-Recording Company. (CTR) was created by
a merger of The Tabulating Machine Company
(Hollerith's punched card company in Washington,
DC), International Time Recording Company (time
clock maker in NY state), Computing Scale Company
(maker of scales and food slicers in Dayton, Ohio),
and Bundy Manufacturing (time clock maker in
Poughkeepsie, NY).  CTR started out with 1,200
employees and a capital value of $17.5 million.

 There is much more information on IBM's history
 in the full version of this software, including
 many pictures of early IBM equipment.

 All major IBM mainframe and mini series are
 listed with date of introduction and a
 description of their importance.  Also included
 are early PC models that used non-descriptive
 model numbers, such as XT and Model 50.





imaging system
See document imaging, image processing and image
enhancement.



IMHO
Digispeak for "in my humble opinion."  See IMO.



information system
A business application of the computer.  It is made
up of the database, application programs, manual
and machine procedures and encompasses the computer
systems that do the processing.

    The database stores the subjects of the business
(master files) and its activities (transaction
files).  The application programs provide the data
entry, updating, query and report processing.  The
manual procedures document how data is obtained for
input and how the system's output is distributed.
Machine procedures instruct the computer how to
perform the batch processing activities, in which
the output of one program is automaticaly fed into
another program.

    The daily processing is the interactive,
realtime processing of the transactions.  At the
end of the day or other period, the batch
processing programs update the master files that
have not been updated since the last cycle.
Reports are printed for the cycle's activities.

    The periodic processing of an information system
is the updating of the master files, which adds,
deletes and changes the information about
customers, employees, vendors and products.


ISCHART.WMF





interface
The connection and interaction between hardware,
software and the user.

    Hardware interfaces are the plugs, sockets,
wires and the electrical pulses travelling through
them in a particular pattern.  Also included are
electrical timing considerations.  Examples are RS-
232 transmission, the Ethernet and Token Ring
network topologies and the IDE, ESDI, SCSI, ISA,
EISA and Micro Channel interfaces.

    Software, or programming, interfaces are the
languages, codes and messages programs use to
communicate with each other and to the hardware.
Examples are the applications that run under the
Mac, DOS and Windows operating systems as well as
the SMTP e-mail and LU 6.2 communications
protocols.

    User interfaces are the keyboards, mice,
commands and menus used for communication between
you and the computer.  Examples are the command
lines in DOS and UNIX and the Mac, Windows and
Motif graphical interfaces.

    Interfacing is a major part of what engineers,
programmers and consultants do.  Users "talk to"
the software.  The software "talks to" the hardware
and other software.  Hardware "talks to" other
hardware.  All this is interfacing.  It has to be
designed, developed, tested and redesigned, and
with each incarnation, a new specification is born
that may become yet one more de facto or regulated
standard.


Format & Function
Every interface implies a structure.  Electrical
signals are made up of voltage levels, frequencies
and duration.  The data passed from one device or
program to another has a precise format (header,
body, trailer, etc.).

    Every interface implies a function.  At the
hardware level, electronic signals activate
functions; data is read, written, transmitted,
received, analyzed for error, etc.  At the software
level, instructions activate the hardware (access
methods, data link protocols, etc.).  At higher
levels, the data transferred or transmitted may
itself request functions to be performed
(client/server, program to program, etc.).


Language & Programming
An interface is activated by programming language
commands.  The complexity of the functions and the
design of the language determine how difficult it
is to program.


User Interface, Protocol, API and ABI
The design of the interaction between the user and
the computer is called a user interface.  The
rules, formats and functions between components in
a communications system or network is called a
protocol.  The language and message formats
between routines within a program or between
software components is called an API.  The
specification for an operating system working in a
specific machine environment is called an ABI.

    All the above interactions are interfaces.
Regardless of what they're called, they all create
rules that must be precisely followed in a digital
world.


INTFACE.WMF





Internet

 The Internet, World Wide Web, intranets
 and all related terms and concepts are
 covered in depth in the full version of
 this software.





Internet Relay Chat
Computer conferencing on the Internet.  There are
hundreds of IRC channels on every subject
conceivable from more than 60 countries.  You have
to log onto an IRC server.  Once logged on, to get
a list of active channels, type /list.  To join a
channel named #HOTSTUFF, type /join #hotstuff.

    After you join a channel, your messages are
broadcast to everyone listening to that channel.
There are IRC programs, such as mIRC, that provide
menus and buttons for all IRC functions including
logging onto popular IRC servers.  See MUD.



Internet utility
Software used to search the Internet for specific
information.  See Archie, Gopher, Veronica, WAIS
and WWW.



intranet

 Intranets, the Internet, World Wide Web
 and all related terms and concepts are
 covered in the full version of this
 software.





IP tunneling
Carrying a foreign protocol within a TCP/IP packet.
For example, IPX can be encapsulated and
transmitted via TCP/IP.



IRQ
(Interrupt ReQuest)  A hardware interrupt on a PC.
Eight lines (0-7 on 8086/88s) and 16 lines (0-15 on
286s and up) accept interrupts from devices such as
a scanner and network adapter.  Unless specifically
programmed to interact together, two devices cannot
use the same line.  If a new expansion board is
preset to the IRQ used by an existing board, one of
them must be changed.  See how to install a PC
peripheral.

    Starting with the 286, the PC uses two 8259A
controller chips to handle the IRQs.  The chips are
cascaded together.  IRQ 2 connects to IRQ 9 of the
second chip.  All the IRQs except for 10, 11, 12
and 15 are preassigned.

    If a second parallel port is not used, IRQ 5 is
available.  IRQ 9 is also often available as most
VGA cards do not require an IRQ.  Thus IRQs 5, 9,
10, 11, 12 and 15 are arbitrarily used for
scanners, SCSI boards, CD-ROM controllers, sound
boards and any other peripheral that can be
attached to a PC.  They become the "IRQ
battleground."


      IRQ  Assignment
      0    System timer
      1    Keyboard
      2    Connects to IRQ 9
      3    COM2, COM4
      4    COM1, COM3
      5    LPT2**
      6    Floppy disk
      7    LPT1
      8    Realtime clock
      9    VGA, 3270 emulation**
     10    **
     11    **
     12    **
     13    Math coprocessor
     14    Hard disk
     15    **

   ** For general use.  "The battleground."





ISA
(1) (Industry Standard Architecture)  Pronounced
"eye-suh."  An expansion bus commonly used in PCs.
It accepts the plug-in boards that control the
video display, disks and other peripherals.  Most
PC expansion boards on the market are ISA boards.

    ISA was originally called the AT bus, because it
was first used in the IBM AT, extending the
original bus from eight to 16 bits.  Most ISA PCs
provides a mix of 8-bit and 16-bit expansion slots.
Contrast with EISA and Micro Channel.  See local
bus.

(2) (Interactive Services Association, 8403
Colesville Road, Silver Spring, MD 20910, 301/495-
4955)  A trade group for the online industry
originally founded in 1981 as the Videotex Industry
Association (VIA).  Members are online services,
service bureaus and hardware and software
companies, all providing products for users with a
computer and modem.


MBOARD.WMF

ISA Slots
This diagram shows a motherboard with two 8-bit
and six 16-bit ISA slots.



CARDS.WMF

Types of Expansion Boards 
There are five major types of expansion boards
that plug into a PC's bus, the ISA board being the
most ubiquitous.  EISA is often
used in high-end servers, and IBM's Micro Channel
is primarily found in older PS/2s.
Pentium systems generally have a combination of
ISA and PCI slots or EISA and PCI slots.





ISDN bonding
The bridging of two or more ISDN channels to
achieve higher data rates.  See ISDN.



ISDN modem
See ISDN terminal adapter.



IsoEthernet
See Isochronous Ethernet.



ISP
See Internet service provider.



ITR
See Internet Talk Radio.



Java
A programming language for World Wide Web
applications from Sun.  Java was modeled after C++,
and Java programs are called from within HTML
documents.  The first Web browsers to run Java
applications are Sun's HotJava and Netscape's
Navigator 2.0.  Java was designed to run in small
amounts of memory and provides its own memory
management.

    Java is an interpreted language that uses an
intermediate step.  The source code of a Java
program is compiled into "byte code," which cannot
be run by itself.  The byte code must be converted
into machine code at runtime.  Upon finding a Java
applet, the Web browser calls the Java interpreter
which translates the byte code into machine code
and runs it.

    Java is a full-blown and difficult programming
language not intended for the casual programmer and
certainly not the end user.  JavaScript, on the
other hand, is a script language from NetScape that
is easier to use, but not as powerful as Java.
JavaScript uses the HTML page as its user
interface, whereas Java can display a completely
customized interface like C and C++.  See
JavaScript.


JAVA.WMF

Java Is Interpreted
Java programs are downloaded into the user's
machine and run by the Java interpreter.  In a
client/server Web application, the server software
may be written in a compiled language for
highest speed since it serves multiple users.





KB, Kb
See kilobyte and kilobit.



Kbit
See kilobit.



Kbits/sec
(KiloBITS per SECond)  Thousand bits per second.



KBps, Kbps
(KiloBytes Per Second, KiloBits Per Second)
Thousand bytes per second.  Thousand bits per
second.



Kbs
(KiloBits per Second)  Same as Kbps.



Kbyte
See kilobyte.



Kbytes/sec
(KiloBYTES per SECond)  Thousand bytes per second.



kiosk
A small, self-standing structure such as a newstand
or ticket booth.  Unattended multimedia kiosks
dispense public information via computer screens.
Either a keyboard, touch screen or both are used
for input.



KIOSK.WMF

The Kiosk
The software in kiosks must be designed for ease
of use.  Touch screens make the interface simple
and straightforward.





LAN administrator
See network administrator.



LAN analyzer
See network analyzer.



LAN Emulation
The ability to connect Ethernet and Token Ring
networks together via ATM.  LAN Emulation (LANE)
makes the process transparent, requiring no
modification to Ethernet and Token Ring stations.
LANE allows common protocols, such as IP, IPX,
AppleTalk and DECnet, to ride over an ATM backbone.

    The LANE driver provides the encapsulation of
Ethernet and Token Ring packets into LANE packets
and then converts the packets into ATM cells.  It
performs the reverse functions on the other end.
The driver resides in an edge device which sits
between the LAN and the ATM switch.  The driver is
also required in each ATM client station that
communicates with Ethernet and Token Ring.

    LANE can also be used to create virtual LANs
(VLANs) in order to logically combine users by
workgroup traffic.  A LAN Emulation Configuration
Server (LECS) provides this capability.  The LAN
Emulation Server (LES) provides address resolution,
and the Broadcast and Unknown Server (BUS) facility
manages multicast and broadcast traffic within the
VLAN.  These services may reside in an ATM switch
or in an attached workstation, server or router.

    The ATM Forum governs the LAN Emulation User-to-
Network Interface (LUNI), which defines how an end
station communicates with the ATM network.

    With LANE, in order to communicate between one
subnet and another, a router is required.  This is
eliminated with MPOA.  See MPOA.



language
A set of symbols and rules used to convey
information.  See machine language, programming
language, graphics language, page description
language, fourth-generation language, standards &
compatibility and user interface.



LCD
(Liquid Crystal Display)  A display technology that
uses rod-shaped molecules (liquid crystals) that
flow like liquid and bend light.  Unenergized, the
crystals direct light through two polarizing
filters, allowing a natural background color to
show.  When energized, they redirect the light to
be absorbed in one of the polarizers, causing the
dark appearance of crossed polarizers to show.  The
more the molecules are twisted, the better the
contrast and viewing angle.

    Because it takes less power to move molecules
than to energize a light-emitting device, LCDs
replaced LEDs in digital watches years ago.  The
LCD was developed in 1963 at RCA's Sarnoff Research
Center in Princeton, NJ.


TYPES OF LCDs

Passive Display (TN and STN)
Called "passive matrix" when used for computer
screens and "passive display" when used for small
readouts, all the active electronics (transistors)
are outside of the display screen.  Passive
displays have improved immensely, but do not
provide a wide viewing angle, and submarining is
noticeable.  The passive display types are:

^    TN (TWISTED NEMATIC - 90 DEGREE TWIST)
^    Low-cost displays for consumer products and
^    instruments.  Black on gray/silver background.

^    STN (SUPERTWISTED NEMATIC- 180-270 DEGREE TWIST)
^    Used extensively on laptops for mono and color
^    displays.  DSTN and FSTN provide improvements
^    over straight STN.
^     180 degree - green/blue on yellow background
^     270 degree - blue on white/blue background

^    DUAL SCAN STN
^    Improves STN display by dividing the screen into
^    two halves and scanning each half simultaneously
^    and doubling the number of lines refreshed.  Not
^    as sharp as active matrix.

^    ACTIVE ADDRESSING
^    Improves STN display by addressing pixels
^    differently.  Eliminates submarining and less
^    expensive than active displays, but not as
^    sharp.  Expected in 1997 timeframe.


Active Display (TFT)
Typically used for laptop color screens, thus
called "active matrix" displays.  Transistors are
built into each pixel within the screen.  For
example, 640x480 color VGA screen requires 921,600
transistors; one for each red, green and blue dot.
Provides a sharp, clear image with good contrast
and eliminates submarining, but fabrication costs
are high.  Uses a 90° (TN) twist.  Also called TFT
LCD (thin film transistor LCD).


Reflective vs Backlit
Reflective screens used in many consumer appliances
and some lightweight laptops require external light
and only work well in a bright room or with a desk
lamp.  Backlit and sidelit screens have their own
light source and work well in dim lighting.


LCD.WMF

Twisted-Nematic Liquid Crystal Display
On side A, the unenergized segment causes the
crystals to line up with the front and rear
polarizers.  The segment appears light
gray, which is actually the light travelling
down and reflected back up the crystals.

On side B, the energized segment causes the
crystals to become perpendicular to the
polarizers.  The segment appears dark, which is
the effect of crossed polarizers.  Most LCDs use a
translucent reflector with light behind it, which
makes the background brighter and the characters
sharper. (Diagram courtesy of LXD, Inc.)





LDAP
(Lightweight Directory Access Protocol)  A protocol
used to access a directory listing.  LDAP support
is being implemented in Web browsers and e-mail
programs, which can query an LDAP-compliant
directory.  It is expected that LDAP will provide a
common method for searching e-mail addresses on the
Internet, eventually leading to a global white
pages.

    LDAP is a simplified version of the DAP
protocol, which is used to gain access to X.500
directories.  It is easier to code the query in
LDAP than in DAP, but LDAP is less comprehensive.
For example, DAP can initiate searches on other
servers if an address is not found, while LDAP
cannot in its initial specification.




Lessons

 Lessons are topic lists that contains the key
 words on various subjects.  In the full version,
 which contains more than 9,000 entries, you could
 set a bookmark and jump to each entry on the list.





Lessons Basics

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  hot topics
  hardware
  software
  data
  computer

  computer system
  program
  analog
  digital
  bit

  binary
  byte
  peripheral
  magnetic recording
  floppy disk

  hard disk
  printer
  monitor
  modem
  operating sytem

  bus
  space/time
  chip
  PC
  Macintosh

  Apple-IBM alliance
  personal computer
  office automation
  x86
  68000

  PowerPC
  how to select a personal computer
  industry topics
  enterprise networking
  standards & compatibility (lots of detail)





Lessons Communications

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  communications
  LAN
  enterprise networking
  OSI
  OSI model

  data link protocol
  client/server
  baseband
  Ethernet
  switched Ethernet

  Token Ring Network
  ARCNET
  FDDI
  ATM
  edge device

  LAN Emulation
  MPOA
  IP Switch
  NetWare
  Lantastic

  Appletalk
  SNA
  TCP/IP
  X Window
  routable protocol

 LAN CONNECTIVITY
   repeater
   bridge
   router
   brouter
   gateway
   hub

 MODEMS
   BBS
   online services
   modem
   emoticon
   RS-232

   V.22bis    2200 bps standard
   V.32       9600 bps standard
   V.32bis   14400 bps standard
   V.34      28800 bps standard
   V.42      error checking
   V.42bis   compression
   MNP       error checking/compression





Lessons Desktop publishing

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  desktop publishing
  font
  typeface
  scalable font
  outline font
  vector font

  halftone
  bitmap
  kerning
  tracking
  leading

  posterization
  color separation
  colors
  point
  prepress

  imagesetter
  page description language
  PCL
  PostScript
  ransom note typography





Lessons Graphics

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  graphics
  paint program
  drawing program
  CAD
  CAD/CAM

  bit depth
  wireframe modeling
  solid modeling
  surface modeling
  ray tracing
  artifact

  Renderman interface
  JPEG
  AutoCAD
  FastCAD
  Bezier

  spline
  GKS
  PHIGS
  bitblt
  PCX

  GIF
  TIFF
  PIC
  HSV
  graphics formats

  metamerism
  gamma correction
  monitor profile
  posertization
  pixelated





Lessons History

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  Pascaline
  Hollerith machine
  ABC
  ENIAC
  UNIVAC I

  punched card
  1401
  650
  IBM mainframes
  IBM minicomputers

  personal computer
  PDP
  VAX
  Altair 8800
  TRS

  PET
  System/360
  Trilogy
  Apple-IBM alliance





Lessons Interesting stuff

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  RTFM
  flame
  hot topics
  droupie
  vaporware

  salary survey
  BBS
  liveware
  phone hawk
  computercruiter

  software vendors
  hardware vendors
  online services
  industry topics
  Big Blue

  hacker
  dweeb
  TLA
  write only code
  buffer flush

  digispeak
  frob
  sneakernet
  boss screen
  ransom note typography

  Easter Egg
  plug and hope
  emoticons
  TTFN
  ROFL

  2000 time problem
  vendors
  hardware vendors
  software vendors
  shareware awards

  FireWire
  videoconferencing
  Systemantics
  cybercafe
  atomic force microscope

  holographic storage
  quantum computing
  Mac clone
  how to spoof your technical friend
  infobahn

  BeBox
  OOBE
  Interpedia
  legality of optical storage
  Versit

  spamming
  trashware
  shelfware
  kludge
  nag screen

  hookemware
  dribbleware
  Stringy Floppy
  avatar





Lessons Internet

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  Internet
  intranet
  Internet address
  Internet references
  Usenet

  hot topics
  TCP/IP
  World Wide Web
  Internet service provider
  Mosaic

  NetScape Navigator
  how to access the Internet
  how to search the Web
  how to transfer a file over the Internet
  URL
  Internet PC

  Yahoo
  ISP
  Web search services
  Web server
  crawler

  digital money
  CU-SeeMe
  HTTPS
  SHTTP
  SSL

  Telnet
  PDIAL
  FTP
  Archie
  Gopher

  Veronica
  Jughead
  Cello
  WAIS
  Finger

  WHOIS
  PING
  newsgroup
  spamming
  Webmaster

  newsreader
  avatar
  mailing list
  thread
  Internet Relay Chat

  Internet Talk Radio
  MUD
  Internaut
  InterNIC
  Mbone

  FAQ file
  Real Audio
  NCSA
  IP address
  RTP





Lessons Job categories

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  user
  systems analyst
  business analyst
  programmer
  programmer analyst

  data administrator
  database administrator
  network administrator
  system administrator
  operator

  salary survey



Lessons Mainframes

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  mainframe
  channel
  front end processor
  communications controller
  TP monitor

  DASD
  IBM mainframes
  VAX
  dumb terminal
  intelligent terminal

  screen scraper
  ES/9000
  System/360
  System/370
  ESA/370

  ESA/390
  3270
  Irma board
  ESCON
  Sysplex

  SNA
  MVS
  VM
  VSE
  CICS

  IMS
  TSO
  SQL
  DB2
  Micro Focus





Lessons Multimedia

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  multimedia
  MPC
  CD
  CD-ROM
  sound card

  MIDI
  MIDI voices
  CD-I
  DVI
  Video CD

  artifact
  hypertext
  Private Eye
  virtual reality
  ScriptX

  Video for Windows
  QuickTime





Lessons Networking
See Lessons Communications.



Lessons Personal computers

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

 CATEGORIES
   personal computer
   how to select a personal computer
   hot topics
   Apple-IBM alliance
   PC

   Macintosh
   Amiga
   MEGA
   laptop
   palmtop


 HARDWARE
   computer
   memory
   floppy disk
   hard disk
   magnetic disk

   keyboard
   modem
   optical disk
   laser printer
   serial port

   parallel port
   game port
   mouse
   tape backup
   how to install a PC peripheral

   x86
   68000
   PowerPC


 BUSES
   bus
   ISA
   EISA
   Micro Channel
   NuBus

   local bus
   VL-bus
   PCI


 ENVIRONMENTS
   operating system
   DOS
   Windows
   Windows NT
   OS/2

   DESQview
   DESQview/X
   UNIX
   DMI


 SOFTWARE
   word processing
   DBMS
   spreadsheet
   business graphics
   communications program

   integrated software package
   paint program
   drawing program


 TUTORIALS
   DOS abc's
   Win 3.1 abc's
   Win 95 abc's
   Pkunzip abc's





Lessons Programming

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  programming
  assembly language
  high-level language
  machine language
  microcode

  reentrant code
  function
  object technology
  object-oriented programming
  macro

  COBOL
  BASIC
  Visual Basic
  FORTRAN
  Pascal

  C
  C++
  Smalltalk
  dBASE
  LISP

  Prolog
  MUMPS
  REXX
  LOGO


 PC PROGRAMMING
   ASCII chart
   hex chart
   binary values
   PC display modes
   PC memory map

   PC color codes
   paragraph
   Turbo C
   Microsoft C
   Borland C++





Lessons System design

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

 OVERVIEW
   information system
   system development cycle
   enterprise networking
   Systemantics


 PEOPLE
   systems analyst
   application programmer
   programmer analyst
   systems programmer
   database administrator

   network administrator
   system administrator
   operator


 DEVELOPMENT
   data administration
   prototyping
   functional specification
   documentation
   CASE
   standards & compatibility


 SOFTWARE
   query language
   report writer
   spreadsheet
   DBMS
   financial planning system

   DSS
   EIS
   EPSS
   expert system
   case-based reasoning





Lessons UNIX

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  UNIX
  open systems
  TCP/IP
  NFS
  NIS

  SMTP
  SNMP
  DNS
  Motif
  Open Look

  Tuxedo
  Encina
  Sequent
  Pyramid
  Encore

  HP 9000
  RS/6000
  OSF
  X/Open
  POSIX

  USL
  X Window
  X terminal
  BSD UNIX
  STREAMS

  emacs
  vi
  awk
  sed
  grep
  UniForum


 UNIX/PC INTEGRATION
   DESQview/X
   SCO Open Server
   Solaris
   Lan Workplace
   UnixWare
   NetWare NFS





Lessons Vendors

 This topic list contains key words on the
 subject.  By setting a bookmark, you can
 jump to each entry in the full version.

  vendors
  hardware vendors
  software vendors
  IBM
  Apple

  Atari
  Commodore
  HP
  Digital Equipment
  Data General

  Bull HN
  Intel
  Motorola
  TI
  Tandy

  Tandem
  Microsoft
  Borland
  Digital Research
  Computer Associates

  D&B Software
  industry topics





load
(1) To copy a program from some source, such as a
disk or tape, into memory for execution.  See boot.

(2) To fill up a disk with data or programs.

(3) To insert a disk or tape into a drive.

(4) In programming, to store data in a register.

(5) In performance measurement, the current use of
a system as a percentage of total capacity.

(6) In electronics, the flow of current through a
circuit.



MAC layer
(Media Access Control layer)  The protocol that
controls access to the physical transmission medium
on a LAN.  The MAC layer is built into the network
adapter.  Common MAC layer standards are the
CSMA/CD architecture used in Ethernet and the token
passing methods used in Token Ring, FDDI and MAP.
The MAC layer is synonymous with the data link
layer in the OSI model.  For a diagram, see "LANs"
under data link protocol.



mailing list
An automated e-mail system on the Internet, which
is maintained by subject matter.  There are more
than 10,000 such lists.  New users generally
subscribe by sending an e-mail with the word
"subscribe" in it and subsequently receive all new
postings made to the list automatically.  Mailing
lists are also called listprocs and listservs,
although the latter comes from the popular LISTSERV
mailing list pacakage.  Majordomo is popular public
domain mailing list program.



master record
A set of data for an individual subject, such as a
customer, employee or vendor.  See master file.



Mathematica
Mathematical software for the Macintosh, DOS,
Windows, OS/2 and various UNIX platforms from
Wolfram Research, Inc., Champaign, IL.  It includes
numerical, graphical and symbolic computation
capabilities, all linked to the Mathematica
programming language.  Its use requires a math
coprocessor.



MCSE
See Microsoft Certified Professional»



MCT
See Microsoft Certified Professional»



memory protection
A technique that prohibits one program from
accidentally clobbering another active program.
Using various different techniques, a protective
boundary is created around the program, and
instructions within the program are prohibited from
referencing data outside of that boundary.

    When a program does go outside of its boundary,
DOS, Windows 3.x and earlier personal computer
operating systems simply lock up (crash, bomb,
abend, etc.).  Operating systems such as UNIX, OS/2
and Windows NT are more robust and generally allow
the errant program to be closed without affecting
the remaining active programs.



Message Handling Service
See MHS.



metafile
A file that contains other files.  It generally
refers to graphics files that can hold vector
drawings and bitmaps.  For example, a Windows
Metafile (WMF) can store pictures in vector
graphics and raster graphics formats as well as
text.  A Computer Graphics Metafile (CGM) also
stores both types of graphics.



MHz
(MegaHertZ)  One million cycles per second.  It is
used to measure the transmission speed of
electronic devices, including channels, buses and
the computer's internal clock.  Megahertz is
generally equivalent to one million bits per second
or to one million times some number of bits per
second.

    When it refers to the computer's clock, it is
used to measure the speed of the CPU.  For example,
a 133MHz Pentium processes data internally
(calculates, compares, copies) twice as fast as a
66MHz Pentium.  However, this does not mean twice
as much finished work gets done in the same time
frame, because cache design, disk speed and
software design all contribute to the computer's
actual performance, not just CPU speed.  See MIPS.


MHz Is the Heartbeat
When referencing CPU speed, the megahertz rating is
really the heartbeat of the computer, providing the
raw, steady pulses that energize the circuits.  If
you know any German, it's easy to remember this.
The word "Herz," pronounced "hayrtz," means heart.


MHZ.WMF

The MegaHertz Speed Limit
MegaHertz is analogous to a highway speed limit.
The higher the speed, the faster the traffic
moves.  In a CPU, the higher the clock rate, the
quicker data gets processed.  The 8-, 16- and 32
bit designation is the CPU's word size and can be
thought of as the number of lanes on the highway.
The more lanes, the more traffic.  The combination
of speed and number of paths determines the total
processing speed or channel bandwidth.





MIDI voices
The number of musical notes that can be played back
simultaneously in a MIDI sound device.  MIDI
provides up to 16 channels of simultaneous
playback.  The number of voices is the total number
of notes from all the instruments played back
through all the channels.

    For example, if one of the channels (patches) is
a piano, up to 10 fingers could strike the keyboard
at the same time, generating 10 notes, assuming
that particular piano patch triggers only one
waveform (see MIDI patch).  Typically, a MIDI sound
card will support from 24 to 32 voices.  Keyboard
synthesizers and sound modules can handle up to 64.



modulate
To vary a carrier wave.  Modulation blends a data
signal (text, voice, etc.) into a carrier for
transmission over a network.  Major methods are AM
(amplitude modulation) - modulate the height of the
carrier wave, FM (frequency modulation) - modulate
the frequency of the wave, and PM (phase
modulation) - modulate the polarity of the wave.
Contrast with demodulate.  See carrier.



morray
See moire.

 Phonetic entries are included in the full
 version of the software.





MPU-401
A MIDI standard from Roland Corporation that has
become the de facto interface for connecting a
personal computer to a MIDI device.



multicast
To transmit a message to multiple recipents at the
same time.  Multicasting is used in
teleconferencing and data communications networks.
Multicast is a one-to-many transmission that
implies sending to several designated recipients,
whereas broadcast implies sending to everyone
connected to the network.  Contrast with unicast.



multidimensional spreadsheet
See spreadsheet.



multiport bridge
A bridge with more than two ports.  There is little
difference between a multiport bridge and a switch,
such as used to switch Ethernet packets, except
that the multiport bridge may introduce some
overhead.  The switch must be able to maintain the
full wire speed of the medium between any two
ports.



National Cristina Foundation
(591 W. Putnam Ave., Greenwich, CT 06830, 800/274-
7846, [e-mail])  A not-for-profit public
charity that seeks donations of used or excess
computers.  Donations are directed, via the NCF
Network of grassroots partner organizations, to
programs involved in the education, rehabilitiation
and job training of people with disabilities,
students at risk of failing and the disadvantaged.

    NCF has helped hundreds of thousands of people
throughout the U.S. and abroad.  It also assists
corporations with long-range planning for
donations.  Corporate donors may qualify for
significant tax benefits.  See how to donate old
equipment.





netbooey
See NetBEUI.

 Phonetic entries are included in the full
 version of the software.





network cloud
A cloud-like symbol in a network diagram used to
reduce an entire communications network into points
of entry and exit.  It infers that although there
may be any number of switches, routers, trunks, and
other network devices within the cloud, the point
of interconnection to the cloud (network) is the
only technical issue in the diagram.  Clouds are
often used to depict a WAN (wide area network).


CLOUD.WMF

Network Cloud
The cloud symbol represents communications
services without specific details of the network
architecture.  The user is only responsible for
getting data into and out of the network.





network computer
(1) A computer in the network.

(2) (Network Computer)  An Internet PC from Oracle
Corporation that uses the NCOS operating sytstem.
It is expected in 1996.  Oracle is one of the first
U.S. companies to develop an Internet PC.  Oracle
is also expected to license the technology.



network segment
See LAN segment.



nonlinear video
See nonlinear video editing.



Novell network
A LAN controlled by one of Novell's NetWare
operating systems.  See NetWare.



NT
See Windows NT.



object
(1) In object-oriented programming, a self-
contained module of data and its associated
processing.  Objects are the software building
blocks of object technology.  See object technology
and object-oriented programming.

(2) In a compound document, an independent block of
data, text or graphics that was created by a
separate application.



Object Management Architecture
A definition of a standard object model from the
Object Management Group.  It defines the behavior
of objects in a distributed environment.  The
communications component of the Object Management
Architecture, or OMA, is the Common Object Request
Broker, or CORBA.  CORBA is often referenced more
than OMA, but it is part of OMA and thus implies
OMA.  See CORBA.



object-oriented technology
Same as object technology.



objects
See object technology and object-oriented
programming.



OC-3
Refers to the SONET transmission rate of 155 Mbps,
which is widely deployed in ATM networks.  See ATM
and SONET.



olay
See OLE.

 Phonetic entries are included in the full
 version of the software.





OLE container
An OLE application that contains the linked or
embedded object.  See OLE.



OODB
See object-oriented database.



Open Database Connectivity
See ODBC.



Open Server
See SCO Open Server.



optical storage
See optical disk and legality of optical storage.



optical storage library
See optical disk library.



Oracle Data Query
See Developer/2000.



Order Form
The Encyclopedia can be ordered by phone, mail, fax
or via the Web: www.computerlanguage.com.  To use
this form, move the dotted line to the top of the
text window and select PRINT TEXT from the File
menu.

    License this software for your networks
              and stand-alone PCs.
   ADD YOUR OWN TERMS WITH MULTIUSER LICENSES!

 .............................................
 To print this, select FILE/PRINT TEXT.

 THE COMPUTER LANGUAGE COMPANY INC.
 P.O.Box 265, Point Pleasant, PA 18950-0265
 Voice 215 297-5999        FAX [phone]

 Name_______________________________________

 Company____________________________________

 Address____________________________________

 City_________________ State___ Zip_________

 Telephone__________________________________

 Circle payment method: Check  M/C  Visa  Amex
 Card #__________________________________________
 Exp. date____/____
 Signature_______________________________________

 Quantity                     Price (US $)
 FOR WINDOWS 3.1, 95 AND NT
 ____ CD-ROM (700 illus./photos)     39.95 _______
 ____ Floppy (300 illustrations)     29.95 _______

 MULTIUSER & NETWORK LICENSES
 (Upgrades 30% of initial fee.)
 ____ 25-user single site           150.00 _______
 ____ 50-user single site           225.00 _______
 ____ 100-user single site          300.00 _______
 ____ 250-user single site          600.00 _______
 Call 215 297-5999 for additional quotes.

 (demo.7.96)                     Subtotal  _______

              PA residents, add sales tax  _______
    SHIPPING: Within United States    5.00
              Within Canada           6.00
              Other countries        10.00 _______
                                   Total  $_______




organizer
See PIM and PDA.



OSI
(Open System Interconnection)  An ISO standard for
worldwide communications that defines a framework
for implementing protocols in seven layers.

    Control is passed from one layer to the next,
starting at the application layer in one station,
proceeding to the bottom layer, over the channel to
the next station and back up the hierarchy.

    Most of this functionality exists in all
communications networks; however, non-OSI systems
often incorporate two or three layers into one.

    Vendors have agreed to support OSI in one form
or another; however OSI serves more as a model than
a universal standard.  Many OSI components are too
loosely defined, and proprietary standards are
entrenched.  One exception is the OSI-compliant
X.400 e-mail protocol that is widely implemented.

    Learning the OSI layers and functions is
essential for understanding communications
networks.  See OSI model.

 A diagram of the OSI model is included in the
 full version of this software.  The major
 protocols are diagrammed in comparison to
 the OSI model.





oversampling
Creating a more accurate digital representation of
an analog signal.  In order to work with real-world
signals in the computer, analog signals are sampled
some number of times per second (frequency) and
converted into digital code.  Using averaging and
different algorithms, samples can be generated
between existing samples, creating more digital
information for complex signals, "smoothing out the
curve" so to speak.

    Sampling requires at least twice the bandwidth
of the frequency being sampled.  For example, with
regard to sound, 20KHz is the highest frequency
perceptible to the human ear, and sampling is done
at 44.1KHz for high quality audio playback.  A 2x
oversampling means that the CD player runs at twice
the rate, or 88.2KHz, and inserts a made-up sample
in between each real sample on the disc.  An 8x
oversampling runs eight times faster and so on.
See sampling rate.



page mode memory
The common dynamic RAM chip design.  Memory bits
are accessed by row and column coordinates.
Without page mode, each bit is accessed by pulsing
the row and column select lines.  With page mode,
the row (page) is selected only once for all bits
(columns) within the row, resulting in faster
access.

    Page mode memory is also called fast page mode
memory.  The "fast" designation was added back when
newer chips ran at 100 nanoseconds and faster.



parity memory
Memory that uses a ninth bit for parity checking.
See parity checking.



PC configuration
See how to install a PC peripheral and plug and
play.



PC conflicts
The clash between devices competing for the same
resouces in the PC.  See how to install a PC
peripheral.



PC EXPO

 In the full version of this software, the
 annual schedules of upcoming major computer
 shows are included.





PC memory map
The following chart shows how the first megabyte of
RAM is used in a PC.


MEMMAP.WMF

Memory Allocation in a PC





Pentium Pro
Currently, the fastest CPU in the Intel x86 line.
Pentium Pro refers to the Pentium Pro CPU chip or
the PC that uses it.  Introduced in 1995, initial
models run at 150MHz and 166MHz, and faster chips
up to 300MHz are planned.  Initial tests of the
Pentium Pro indicate that the chip is better suited
to running 32-bit operating systems and
applications, and performance is degraded when
running 16-bit applications.

    It is expected that the Pentium will become the
entry-level desktop CPU chip, and the Pentium Pro
will be used in servers and high-end workstations,
many of which will employ a symmetric
multiprocessing (SMP) architecture where two or
more CPU chips are used to increase performance.





performance ratings
See DOSmark, Winmark, SPECmark, Landmark rating,
Dhrystones, Whetstones, iCOMP, PLB and MIPS.



persistent data
Data that exists from session to session.
Persistent data is stored in a database on disk or
tape.  Contrast with transient data.



personal communications services
See PCS.



personal communicator
See PDA.



personal digital assistant
See PDA.



personal information manager
See PIM.



Personal Intelligent Communicator
See PIC.



personal workstation
Same as personal computer or workstation.



PGP
(Pretty Good Privacy)  A public key cryptography
method developed by Phil Zimmermann that is based
on RSA.  A version for personal, non-business use
is available on various BBSs and Internet hosts.  A
commercial version of PGP is available for UNIX,
DOS, Windows and Mac platforms from Viacrypt,
Phoenix, AZ.  See cryptography.



phono connector
Also called an RCA connector, a plug and socket for
a two-wire coaxial cable used to connect audio and
video components.  The Apple II has a video out
phono connector for a TV.  The plug is a 1/8" thick
prong that sticks out 5/16" from the middle of a
cylinder.  See phone connector.


PHONOCON.WMF


 In the full version of this software, all the
 important plugs, sockets and connectors are
 explained and diagrammed such as this one.





pivot table
A multidimensional data structure which allows the
user to quickly switch to different views of the
data.  Pivot tables are created in spreadsheets and
database programs.


DSS_EIS.WMF

Multidimensional Views
The ability to quickly switch between one slice of
data and another allows users to analyze their
information in small palatable chunks instead of
reading giant reports that are confusing.





plug and hope
Refers to the frustration of installing additional
peripheral devices on a PC.  See plug and tell,
plug and play and how to install a PC peripheral.



PM
See preventive maintenance, Presentation Manager,
Program Manager and phase modulation.



PMJI
Digispeak for "pardon my jumping in."



POP
(1) (Point of Presence)  The point at which a line
from a long distance carrier (IXC) connects to the
line of the local telephone company or to the user
if the local company is not involved.  For online
services and Internet providers, the POP is the
local exchange users dial into via modem.

(2) (Post Office Protocol)  A messaging protocol
commonly used on the Internet.  It stores and
forwards e-mail to users that log onto the mail
server.  POP uses the SMTP message format protocol.
See IMAP and messaging system.

(3) An instruction that retrieves an item from a
stack.  See push/pop.



port 80
The default port address used to link incoming Web
traffic to the appropriate application program.
See port address.



POTS
(Plain Old Telephone Service)  The traditional
analog telephone network.  See AMPS.



PowerPC
A family of CPU chips designed by Apple, IBM and
Motorola, introduced in 1993.  Both IBM and
Motorola offer the chips for sale, but IBM owns the
architecture.  The PowerPC is designed to span a
range of computing devices from hand-held machines
to supercomputers.  For example, it is used in
Apple's Pippin multimedia CD-ROM player.

    To date, PowerPC chips have been mostly used as
the CPUs in PowerMacs, which run a version of
System 7 that supports older Mac applications as
well.  IBM is using the PowerPC chips in certain
RS/6000 models and is offering PowerPC systems that
run AIX and Windows NT.  NetWare and Solaris have
also been announced for the PowerPC, but OS/2 on
the PowerPC has been dropped.


PowerPC CPU Technical Specs
The PowerPC is a refined version of IBM's RS/6000
single-chip CPU.  It is a RISC-based 32-bit
multitasking microprocessor that has an internal
64-bit data path to memory similar to the Pentium.

    The first PowerPC chip, the 601 (MPC601), runs
at 50 and 66MHz and is as fast or faster than a
Pentium, but is half the size and uses half the
electricity.  A low-power 603 is designed for
notebooks and runs at 75MHz.  The 603e raises the
speed to 100MHz and doubles the internal cache to
32KB.  An ultra-low power 602 has been designed for
consumer products.  The 604 is approximately 50 to
100% faster than the 601 depending on clock speed,
and the upcoming 620 is expected to be at least
twice as fast as the 601.  See PPCP.





PPD file
(PostScript Printer Description file)  A file that
contains detailed information about a particular
printer.  Although PostScript is a device-
independent language, the PostScript driver uses
information in the PPD file to take advantage of
special features in the target printer or
imagesetter.  The PPD file is an ASCII file that
can be transferred between PCs and Macs.



Pretty Good Privacy
See PGP.



private key
The private part of a two-part, public key
cryptography system.  The private key is kept
secret and never transmitted over a network.  See
RSA and cryptography.



protocol stack
The hierarchy of protocols used in a communications
network.  Network architectures designed in layers,
such as TCP/IP, OSI and SNA, are referred to as
stacks.  See OSI model.



proxy server
A server that converts internal station addresses
to international Internet IP addresses.  For
example, if an organization maintains an intranet,
it can assign IP addresses to its own local
machines that are not recognized by the Internet at
large.  A major online service that has its own
addressing system would use a proxy server to link
its customers to the Internet.

    A proxy server is also used as a firewall
between an intranet and the Internet.  It can
prevent unauthorized inbound traffic and restrict
downloading by blocking specific Web sites.  It can
also log and report on what sites users are
viewing.  In order to improve Web performance, the
proxy server may be able to cache Web pages, so
that frequently-used pages are available locally.



PU 2.1
(Physical Unit 2.1)  In SNA, the original term for
Node Type 2.1, which is software that provides
peer-to-peer communications between intelligent
devices (PCs, workstations, minicomputers).  Only
LU 6.2 sessions are supported between Type 2.1
nodes (PU 2.1).



Px64
An ITU standard for transmitting audio and video in
64 Kbits/sec ISDN channels (P represents number of
channels used).  Although video conferencing can be
done in only one or two channels, more channels are
required for smooth motion.

    Px64 uses two screen formats.  The CIF (Common
Intermediate Format) generates a 352x288
resolution, while QCIF (Quarter CIF) is 176x144.
CIF transmits at 36.45 Mbits/sec; QCIF is 9.115
Mbits/sec.  See H.261.



QIC
(Quarter Inch Cartridge)  A magnetic tape
technology used for backing up data.  QIC tapes
come in two form factors: 3.5" Minicartridges and
5.25" Data Cartridges.  The Minicartridges use
.25"-wide and .315"-wide tape in several drive and
cartridge options.  Data Cartridges only use .25"
tape and are expected to slow in usage in favor of
Minicartridge, DAT, 8mm and DLT formats.

    The original QIC-40 40MB Minicartridge is
obsolete.  Today, the most common Minicartridge is
QIC-80 with an uncompressed capacity of 125MB.
Since most backup is compressed, QIC capacities are
often stated as double the raw amount.  But
doubling is an approximation.  Some files do not
compress well at all.

    The original DC-2000 Minicartridge used .25"
tape, hence the quarter-inch name, but QIC-Wide
tapes increased the width to .315".  QIC-Wide
drives are required for QIC-Wide tapes.  The Travan
drive uses the .315" tape, but extends the length.
Travan drives also read and write QIC-Wide tapes.
QIC-EX cartridges come in both .25" and .315"
formats and, using longer tape, extend the capacity
of existing drives.

    There are numerous QIC cartridge designations.
DC-2000 is used generically for QIC-80
Minicartridges, the 2120 cartridge being the most
common.  DC-6000 is used generically for the 5.25"
cartridges.

QIC.WMF

QIC Cartridge
QIC cartridges have a supply and takeup hub as do
tape cassettes.  However, the hubs are moved by
a drive belt (red) that wraps around them.  The
drive belt is pinched between the capstan and the
drive motor when the cartridge is inserted into
the drive.

    The following chart shows the remaining QIC
formats and their capacities.  There have been
other 3.5" and 5.25" formats that fallen by the
wayside.

        MINICARTRIDGE CAPACITIES (3.5")
 Each of the following cartridge types and
 QIC formats requires a specific cartridge.

          QIC CARTRIDGE TYPE:
 QIC         QIC                      .315"
 Format   (DC-2000) QIC-Wide  Travan  QIC-EX
 QIC-80     125MB    200MB    400MB   500MB
 QIC-3010   340MB    420MB    800MB   1.1GB
 QIC-3020   680MB    850MB    1.6GB   2.2GB
 QIC-3040   840MB      1GB            2.5GB
 QIC-3050     1GB    1.3GB    2.3GB   3.1GB
 QIC-3080   1.6GB      2GB              5GB
 QIC-3095              2GB      4GB     5GB
 QIC-3210            2.3GB            5.1GB
 QIC-3230              8GB     15GB    20GB


      DATA CARTRIDGE CAPACITIES (5.25")

            QIC Type  DC 6000
            QIC-150   250MB
            QIC-525   525MB
            QIC-1000    1GB
            QIC-2GB     2GB
            QIC-5GB     5GB
            QIC-5010   13GB
            QIC-5210   25GB


FREEQIC.WMF





quality of service
See QoS.



R/3
An integrated suite of client/server applications
from SAP America, Inc.  It is the client/server
versions of SAP's R/2 mainframe applications.  R/3
includes information systems for manufacturing,
distribution, order processing, accounting and
human resources.  It includes the ABAP/4
Development Workbench.



RACF
(Resource Access Control Facility)  IBM mainframe
security software introduced in 1976 that verifies
user ID and password and controls access to
authorized files and resources.



RAID
(Redundant Array of Independent Disks)  A category
of disk arrays (two or more drives working
together) that provide increased performance and
various levels of error recovery and fault
tolerance.  RAID can be implemented in software
using standard disk controllers, or it can be
designed into the disk controller itself.

    The term used to mean Redundant Arrays of
Inexpensive Disks, which was the title of a paper
written in 1988 by the University of California at
Berkeley.  RAIDs were contrasted with SLEDs (Single
Large Expensive Disks), which were still popular on
large computers.  Today, all hard disks are
inexpensive by comparison, and The RAID Advisory
Board, St. Peter, MN, which sanctions RAID
terminology and architecture, has changed the name
to "independent disks."

 In the full version of this software,
 all the important RAID levels are defined
 with diagrams and comparison charts.





ransom note typography
Using too many fonts in a document.  The term comes
from the text in a ransom note that is pasted
together from words cut out of different magazines
and newspapers.

    The ease with which fonts can be selected in a
word processor has led many inexperienced people to
use too many fonts in a document or newsletter.
Typographers and graphics artists know that only
two or three fonts are necessary for the most
professional appearance.



RDBMS
(Relational DataBase Management System)  See
relational database.



Real Audio
An Internet audio playback system from Progressive
Networks Inc., Seattle, WA.  Real Audio encoders
and players for Windows and Mac can be downloaded
free from http://www.realaudio.com.  The players
can be plugged into most Web browsers, such as
NetScape and Mosaic.  Real Audio allows news,
sports and broadcasts of all types to be placed on
the Internet for anyone in the world to listen to.

    Real Audio uses Progressive's proprietary .RA
and .RAM audio formats.  Although audio files can
be encoded, stored on the Net, downloaded and
played using free Real Audio products, the key to
this is being able to hear the audio as it is being
downloaded by the user.  Real Audio server
software, which must be licensed, provides this
capability and is available on Windows, Mac,
PowerMac, Sun, SGI and UNIX platforms.



Red Book
(1) The documentation of the U.S. National Security
Agency that defines criteria for secure networks.
The volumes are "Trusted Network Interpretation of
the Trusted Computer System Evaluation Criteria"
(NCSC-TG-005) and "Trusted Network Interpetation
Environments Guideline: Guidance for Applying the
Trusted Network Interpretation" (NCSC-TG-011).  It
is the network counterpart of the Orange Book for
computers.  See NCSC.

(2) The documentation for the technical
specification of audio CDs (CD-DA), which includes
such details as sampling and transfer rates.  "Red
Book audio" refers to digital sound that conforms
to the common standard used in music compact discs.
See CD.



resolution
(1) The degree of sharpness of a displayed or
printed character or image.  On screen, resolution
is expressed as a matrix of dots.  VGA resolution
of 640x480 means 640 dots across each of 480 lines.
Sometimes the number of colors are added to the
spec; for example, 640x480x16 or 640x480x256.  The
same resolution looks sharper on a small screen
than a large one.  See PC display modes and how to
select a PC display system.

    For printers, resolution is expressed as the
number of dots per linear inch.  300 dpi means
90,000 dots per square inch (300x300).  Laser
printers and plotters have resolutions from 300 to
1000 dpi and more, whereas most display screens
provide less than 100 dpi.  That means jagged lines
on screen may smooth out when they print.

(2) The number of bits used to record the value of
a sample in a digitized signal.  See sampling rate.


RESOLUTN.WMF

Screen Resolutions
These are the screen resolutions that are used on
a PC.  There are higher resolutions for special
applications, such as document imaging.
The higher the resolution, the more
information (pixels) can be displayed on screen at
one time.





RUMBA
A family of PC-to-host connectivity software from
Wall Data Inc., Kirkland, WA.  RUMBA provides
Windows, Windows NT Workstation and OS/2 front ends
to IBM mainframes, AS/400s and VAXes through a wide
variety of network configurations.  RUMBA coax
adapters (3270 emulators) are also available.

 In the full version of this software, all
 software packages widely used in niche areas
 are described.





salary survey

 The full version of this software contains
 the lastest salary survey from Source Edp.
 It shows what computer professionals earn,
 where they earn it and what each job entails.





SCADA
(System Control and Data Acquisition, Supervisory
Control and Data Acquisition, Security, Control and
Data Acquisition).  A common process control
application that collects data from sensors on the
shop floor or in remote locations and sends them to
a central computer for management and control.



SCO Open Desktop
See SCO Open Server.



screen scraper
Also called frontware, it is software that adds a
graphical user interface to character-based
mainframe and minicomputer applications.  The
screen scraper application runs in the personal
computer which is used as a terminal to the
mainframe or mini via 3270 or 5250 emulation.

    Popular screen scrapers are Knowledgeware's
Flashpoint, Mozart Systems Corporation's Mozart and
Easel's ESL Renovator.  Attachmate's QuickApp adds
screen scraper capability to development systems
such as PowerBuilder, Visual Basic and SQLWindows.



scuzzy
See SCSI.

 Phonetic entries are included in the full
 version of the software.





seashell
The "C" shell in UNIX.  See UNIX.



security protocol
A communications protocol that encrypts and
decrypts a message for online transmission.
Security protocols generally also provide
authentication.  The security protocols emerging on
the Web are NetScape's SSL, NCSA's SHTTP and
Microsoft's PCT.  Web broswers and servers are
expected to support all the popular security
protocols.  See HTTPS.



segmented address space
Memory addressing in which each byte is referenced
by a segment, or base, number and an offset that is
added to it.

    A PC running in 16-bit mode (Real Mode) uses a
segmented address space.  Memory is broken up into
64KB segments, and a segment register always points
to the base of the segment that is currently being
addressed.  The PC's 32-bit mode is considered a
flat address space, but it too uses segments.
However, since one 32-bit segment addresses 4GB,
one segment covers all of memory.



Serial Line IP
See SLIP.



seven dwarfs
IBM's early competitors in the mainframe business:
Burroughs, CDC, GE, Honeywell, NCR, RCA and Univac.



shared Ethernet
Refers to the traditional Ethernet topology in
which all stations share the total bandwidth of the
network.  Whether connected via a common cable
(10Base5, 10Base2) or a hub (10BaseT), transmission
is on a first-come, first-served basis.  Contrast
with switched Ethernet, in which each sender and
receiver pair has the full bandwidth of the line.



SHTTP
(Secure HTTP)  A protocol that provides secure
transactions over the World Wide Web.  It is
endorsed by NCSA and a variety of organizations.
See security protocol.



Silicon Graphics
See SGI.



SimCity 2000
A popular educational game for kids and adults for
DOS and Macintosh from Maxis, Orinda, CA.  The
purpose is to create a city that literally expands
itself if the infrastructure is well designed.
After installing a power plant, electric lines,
highways and setting up residential and commercial
zones, the people come and build up the city.  You
can influence the politics, taxation, even
determine how much natural disaster befalls the
citizens.  It's quite amazing!



SIMM converter
A printed circuit board that allows older 30-pin
SIMMs to be plugged into the newer 72-pin socket.
The board contains a 72-pin plug and a number of
30-pin sockets.  SIMM converters are also used to
expand a single 30-pin or 72-pin socket to multiple
SIMM modules.



Simple Mail Transfer Protocol
See SMTP.



Simple Network Managment Protocol
See SNMP.



software engineering
The design, development and documentation of
software.  See CASE, systems analysis & design,
programming, object-oriented programming, software
metrics and Systemantics.



software vendors

 The full version of this software contains
 Software Magazine's latest ranking of the
 top 100 software companies.





space/time
The following units of measure are used to define
storage and transmission capacities.  See binary
values.

   S P A C E  -  Bits or bytes
                       Power of 10
   Kilo  (K)  Thousand       3
   Mega  (M)  Million        6
   Giga  (G)  Billion        9
   Tera  (T)  Trillion      12
   Peta  (P)  Quadrillion   15
   Exa   (E)  Quintillion   18
   Zetta (Z)  Sextillion    21
   Yotta (Y)  Septillion    24


  T I M E -  Fraction of second
                                Power of 10
  Millisecond (ms)  Thousandth       -3
  Microsecond (µs)  Millionth        -6
  Nanosecond  (ns)  Billionth        -9
  Picosecond  (ps)  Trillionth      -12
  Femtosecond (fs)  Quadrillionth   -15
  Attosecond  (as)  Quintillionth   -18
  Zeposecond  (zs)  Sextillionth    -21
  Yoctosecond (ys)  Septillionth    -24


 Storage/channel capacity measured in:
 CPU word size           Bits
 Bus size                Bits
 Disk, tape              Bytes
 MEMORY
  Overall capacity       Bytes
  SIMM or SIP module     Bytes
  Individual chip        Bits

 Transmission speed measured in:
 Network line/channel      Bits per second
 Disk transfer rate        Bits or bytes per second
 Disk access time          Milliseconds
 Memory access time        Nanoseconds
 Machine cycle             Microseconds/Nanoseconds
 Instruction execution     Microseconds/Nanoseconds
 Transistor switching      Nanoseconds, Picoseconds
                            and Femtoseconds





stack overflow
An error condition that occurs when there is no
room in the stack for a new item.  Contrast with
stack underflow.

    In DOS, a Stack overflow error message means
that there is not enough room on the stack to
handle hardware interrupts.  Increase the number of
stacks in the STACKS= command in the CONFIG.SYS
file (see DOS Stacks).

    You can also get this message when other things
go haywire; for example, a bad expansion board or
one that isn't seated properly in the slot can
cause erratic signals eventually leading to this
message.





switch fabric
The physical interconnect architecture used by a
switching device, which redirects the data coming
in on one of its ports out to another of its ports.



Synon/2E
An integrated development environment for AS/400s
from Synon, Inc., Larkspur, CA.  Synon/2E was
introduced in the same year as the AS/400 (1988)
and is the leading tools product in this market.
It provides an upper and lower CASE environment
that generates COBOL and RPG code.  Synon was
founded in England in 1983 by Simon Williams.  The
name came from and is pronounced "sign on."

    Synon's Obsydian is an object-oriented PC-based
environment that is used to develop C++ code for
Windows clients and RPG code for AS/400 servers.



systems programmer
(1) In the IS department of a large organization, a
technical expert on some or all of the computer's
system software (operating systems, networks,
DBMSs, etc.).  They are responsible for the
efficient performance of the computer systems.

    They usually don't write programs, but perform a
lot of technical tasks that integrate vendors'
software.  They also act as technical advisors to
systems analysts, application programmers and
operations personnel.  For example, they would know
whether additional tasks could be added to the
computer and would recommend conversion to a new
operating or database system in order to optimize
performance.

    In mainframe environments, there is one systems
programmer for about 10 or more application
programmers, and systems programmers generally have
considerably higher salaries than application
programmers.  In smaller environments, users rely
on vendors or consultants for systems programming
assistance.  In fact, end users are actually
performing systems programmer functions when they
install new software or hardware on their own
personal computers.  See system administrator and
salary survey.

(2) In a computer hardware or software
organization, a person who designs and writes
system software.  In this case, a systems
programmer is a programmer in the traditional sense
and is often called a software engineer.  See
salary survey.



TAPI
(Telephony API)  A programming interface from
Microsoft and Intel that is part of Microsoft's
WOSA architecture.  It allows Windows client
applications to access voice services on a server.
TAPI is designed to provide interoperability
between PCs and telephone equipment, including
phone systems and PBXs.  See WOSA.



teleconferencing
("long distance" conferencing)  A communications
session among several people that are
geographically separated.  See videoconferencing,
audioconferencing, computer conferencing and data
conferencing.



TeX
A typesetting language used in a variety of
typesetting environments.  It uses embedded codes
within the text of the document to initiate changes
in layout including the ability to describe
elaborate scientific formulas.



the Web
See World Wide Web.



thermal dye transfer
See dye sublimation.




Token Ring connector
Called a Type 1 connector and developed by IBM, it
is a combination plug and socket.  Flip any
connector 180 degrees with the other and they plug
together.


TYPE1CON.WMF

 In the full version of this software, all the
 important plugs, sockets and connectors are
 explained and diagrammed such as this one.





transport protocol
A communications protocol responsible for
establishing a connection and ensuring that all
data has arrived safely.  It is defined in layer 4
of the OSI model.  Often, the term transport
protocol implies transport services, which includes
the lower level data link protocol that moves
packets from one node to another.  See OSI model
and transport services.



Travan
An enhanced QIC tape drive that reads and writes
Travan and QIC-Wide minicartridges.  The common
QIC-80 cartridge holds 125MB of uncompressed data,
whereas the equivalent Travan tape holds 400MB.
See QIC.



two-phase commit
A technique for ensuring that a transaction
successfully updates all appropriate files in a
distributed database environment.  All DBMSs
involved in the transaction first confirm that the
transaction has been received and is recoverable
(stored on disk).  Then each DBMS is told to commit
the transaction (do the actual updating).



U.S. Robotics
(U.S. Robotics, Inc., Skokie, IL)  A modem
manufacturer highly regarded for its quality
modems.  The company manufactures its own chipsets
(data pumps) and often leads the industry with
innovations.  Its HST protocol was a high-speed and
reliable modem protocol before V.32bis became a
standard.

 In the full version of this software,
 backgrounders on the major hardware and
 software vendors are included.





UMB
(Upper Memory Block)  Unused blocks in the UMA
(640K-1M).  A UMB provider, such as EMM386.EXE, is
software that can load and manage drivers and TSRs
in these unoccupied areas.  See PC memory map, PC
conflicts, DOS Dos and DOS EMM386.EXE.


MEMMAP.WMF

Memory Allocation in a PC





UNC
(Universal Naming Convention)  A standard for
identifying servers, printers and other resources
in a network, which originated in the UNIX
community.  A UNC path uses double slashes or
backslashes to precede the name of the computer.
The path (disk and directories) within the computer
are separated with a single slash or backslash, as
follows:

      //servername/path     UNIX

      \\servername\path     DOS/Windows





UniSQL
An object-oriented DBMS from UniSQL, Austin, TX.
UniSQL/X is a relational and object-oriented DBMS
for UNIX servers that provides SQL and object
access to the database.  UniSQL/M adds object-
oriented capability to SQL Server, Oracle, Ingres
and other relational DBMSs.



UNIX 93
An X/Open brand used on a product that is compliant
with a number of UNIX-based specifications
including XPG3, XPG4, SVID and AT&T source code.
In early 1996, X/Open closed this branding.  See
X/Open.



UNIX 95
An X/Open brand used on a product that is compliant
with the Single UNIX Specification (formerly Spec
1170).  See X/Open.



UNIX shell account
A customer account with an Internet access provider
that requires the user to enter UNIX commands to
send and receive mail and files.  Prior to today's
graphical interfaces, Internet access was always a
command line operation performed by researchers and
computer buffs.



UNIX socket
A UNIX communications interface that lets an
application access a network protocol by "opening a
socket" and declaring a destination.  Sockets are
very popular because they provide a simple way to
direct an application onto the network (TCP/IP
protocol).  NetWare 3.x also supports sockets as
one of the common transport interfaces.



UNIX to UNIX copy
See UUCP.



v-mail
(Video mail)  The ability to send video clips along
with e-mail messages.  This is not the same as
videoconferencing, which requires realtime
capabilities between sender and receiver, but it
does require high-speed computers and networks.



VBRUN300.DLL
(Visual Basic RUNtime 300.DLL)  The Visual Basic
runtime module.  A Visual Basic application is made
up of a series of calls to Visual Basic routines,
which are contained in the DLL, and VBRUNxxx.DLL
must be available to run them.  The number
represents the version of Visual Basic (VBRUN300,
VBRUN400, etc.).



VFAT
(Virtual File Allocation Table)  The file system
used in Windows for Workgroups and Windows 95.  It
provides 32-bit Protected Mode access for file
manipulation.  VFAT is faster than, but also
compatible with, the DOS 16-bit File Allocation
Table (FAT).  In Windows for Workgroups, VFAT was
called 32-bit file access.  In Windows 95, it
supports long file names up to 255 characters.



VGA feature connector
A point-to-point channel used to transfer video
signals between two video controllers, typically
between the display adapter and a video capture or
TV board.  Using an 8-bit data path, it provides 40
Mbytes/sec bandwidth.  The port is a 26-pin male
connector or a 26-pin (13 per side) edge connector
at the top of the VGA board.  See VESA Advanced
Feature Connector.


FEATCON.WMF

Feature Connector
The VGA feature connector is either a 26-pin male
connector on the chip side of the VGA adapter or a
26-pin (13 pins on each side) edge connector on
the top edge.  All VGA boards do not have the
feature connector.





video adapter
See video capture board, video graphics board and
display adapter.



video RAM
Also called VRAM, it is a type of memory used in a
display adapter.  It is designed with dual ports so
that it can simultaneously refresh the screen while
text and images are drawn in memory.  It is faster
than the common dynamic RAM (DRAM) used as main
memory in the computer.



video teleconferencing
See videoconferencing.



viewer
A program that displays the contents of an
electronic (digital) file.  Viewers may be stand-
alone programs or components within a larger
program.  They are widely used to display images
downloaded from BBSs, online services and the
Internet.  Viewers for sound and video files are
also available.

    A viewer typically displays or plays one type of
file, whereas a file viewer is a program that
supports many different formats.  See file viewer.



virtual device driver
See VxD.



VLAN
See virtual LAN.



VRML
(Virtual Reality Modeling Language)  The
specification for a 3-D graphics language for the
World Wide Web.  After downloading a VRML page, its
contents can be viewed, rotated and manipulated,
and simulated rooms can be "walked into."  The VRML
viewer is launched from within the Web browser.

    The first VRML viewer was WebSpace from SGI,
whose Open Inventor graphics library was the basis
for developing VRML.  WebFX, WorldView and Fountain
are other Windows viewers, and Whurlwind and
Voyager are Mac viewers.



watermark
See digital watermark.



Web PC
See Internet PC.



Web search engines
See Web search services.



white point
The measurement of "white" on a color monitor.  It
can be expressed in degrees Kelvin or as one of the
standard illuminants or in x-y coordinates from the
CIE Chromaticity Diagram.  For example, the most
neutral white point is 6500 degrees Kelvin or D65
or x=0.3127/y=0.3290.



Win 95 abc's
The Win 95 abc's and the Win 95 entries that follow
provide a brief overview of the Windows 95
operating system and how to perform basic
operations.  If you are a Windows 3.1 user, be sure
to read Win 95/3.1 Differences.  The remainder of
this definition is intended for the first-time user
of Windows.

 In the full version of this software, there are
 numerous Win 95 entries that provide how to's
 and tips for Windows 95 users.





Win 95 Properties
A Windows 95 Property sheet displays the current
settings of a particular resource in the computer.
It is also used to modify the settings and serves
as a front end to the Registry, which is the
database where these settings are stored (see Win
95 Registry).

    Property sheets are displayed by selecting the
different Control Panels in My Computer as well as
from the Properties option in the File menu.  Right
clicking on various objects also displays them.
Following are ways to access some useful Property
sheets.


  Desktop and Window Colors and Screen Saver
    Right click on any uncovered part of the
    desktop.


  Hardware Configuration (CPU and Peripherals)
    Double click My Computer, Control Panel and
    System.  Select DEVICE MANAGER.


  TaskBar (Hide or Restore, Show Clock)
    Right click on any uncovered part of the
    Taskbar (in between the buttons).


  Most All Properties Sheets
    Double click My Computer and a Control Panel.





Windows Metafile
A Windows file format that holds vector graphics,
bitmaps and text.  It uses the .WMF file extension
for 16-bit Windows and the .EMF extension for 32-
bit Windows (see EMF).  The Windows Metafile is
Windows' preferred vector format, since it contains
actual Windows commands (GDI calls) to draw the
images.  It is also used by programs to hold data
between sessions, and, Windows sometimes uses it
for temporary storage.

    The Aldus Placeable Metafile is a PageMaker
variation that contains a header indicating into
what size rectangle the object will be rendered.



X Pixelmap
An 8-bit raster graphics format used in the UNIX
environment.  It uses the .XPM extension and is
similar to the X Bitmap format, but provides 256
colors.  X Pixelmaps are often used for X Window
icons and hypertext icons on Web pages.



x86
Refers to the Intel 8086 CPU family (8086, 8088,
80186, 80286, 386, 486, Pentium).  Starting with
the 386, Intel has dropped the "80" prefix in its
reference manuals.  The x86 designation is also
referenced as 80x86.  The following list contains
the members of the x86 family of CPUs.


X86.WMF





Yellow Book
The standard for the physical format of a CD-ROM
disk.  The ISO 9660 standard defines the logical
format for the disk.  See CD.



zeen
See zine.

 Phonetic entries are included in the full
 version of the software.





0x
In programming, the symbol for a hexadecimal
number.  See x.



100VG-AnyLAN
A high-speed version of Ethernet (IEEE 802.12
standard) developed by HP that supports Token Ring
as well as 10BaseT networks.  It is a shared media
LAN like regular Ethernet, but transmits at 100
Mbps rather than 10 Mbps.  It employs the Demand
Priority access method rather than CSMA/CD, which
is used in 10Base and 100BaseT Ethernets.

    Demand Priority is suited to videoconferencing,
because it allows realtime voice and video packets
to be given a higher priority than data.  In the
past, 100VG-AnyLAN has also been called 100BaseVG
and Fast Ethernet, although Fast Ethernet now
refers to 100BaseT.



2000 time problem
The year 2000 presents a problem for many legacy
systems whose databases were designed with two-byte
year fields.  Years ago, saving two bytes in a
record meant alot more than it does today.  A "00"
in the year field is assumed to mean the year 1900,
and financial calculations that deal with aging
will be incorrect.

    Even though many mainframe systems have been
downsized to client/server, databases may have been
converted without extending the two-byte year into
four bytes.  Thus the problem can exist on state-
of-the-art platforms.

    There are consultants that specialize in this
problem and there is software than analyzes and
patches systems to solve it.  However, older
information systems are often programmed by people
that are no longer around and in languages that are
difficult to support.  Thus, many legacy systems
are ticking time bombs, literally.  It has been
estimated that as much as $400 billion will be
spent modifying systems to change the year from two
to four bytes.



3-D modeling
The ability to create three-dimensional images.
See surface modeling and solid modeling.



4GL
See fourth-generation language.



586
See Pentium.



640K
(640 Kilobytes)  Typically refers to the first 640
kilobytes of memory in a PC, known as conventional
memory.  See PC memory and PC memory map.



7-bit ASCII
The original ASCII character code, which provides
for 128 different characters.  Internet mail as
well as certain PBXs support 7-bit ASCII, not the
8-bit byte.  In order to transmit proprietary file
formats and binary executables over these systems,
the 8-bit data must be encoded into a 7-bit format
using such programs as UUencode and BinHex.



802.12
See 100VG-AnyLAN.



9660
See ISO 9660.






END.WMF