Category : Tutorials + Patches
Archive   : PCGLOSRY.ZIP
Filename : GLOSRY.DBV

Output of file : GLOSRY.DBV contained in archive : PCGLOSRY.ZIP
electronic data and programs. It was introduced by IBM with the
AT-class machine. It is 5.25" in diameter, the same physical size
as its predecessor, the 360 K floppy, but can store more than three
times the capacity. The 1.2 MB floppies are referred to as high
capacity or high density diskettes.

A 1.2 MB floppy diskette, that has been formatted with a 1.2 MB
drive, cannot be read or properly written to with a 360 K floppy
disk drive. Because the two disk drives appear to be identical,
this is often a confusing matter for beginners. The 1.2 MB floppy
disk drives, however, can also read and write 360 K floppies.

Generally, a PC or XT-class machine will have a 360 K floppy drive
while an AT-class machine will house a 1.2 MB floppy drive.
¨+A 1.44 MB microdiskette is a magnetic diskette for storing and
retrieving electronic data and programs.

The 1.44 MB microdiskette was introduced in the late 1980's as a
high density 3.5" diskette. It has a data storage capacity of 1.44

A 1.44 MB microdiskette, that has been formatted with a 1.44 MB
high density drive, cannot be read or reliably written to with a
720 K diskette drive. Because the two disk drives and diskettes
appear to be identical, this is often a confusing matter for
beginners. The 1.44 MB microdiskette drives, however, can also
read and write 720 K diskettes.

See the table "Floppy Disk Specifications" for an overview.
Te10Base-T is the communication standard approved in September
of 1990 by the IEEE. 10Base-T, or 802.3i, is the standard for
running 10 megabits per second Ethernet LANs over unshielded
twisted-pair wiring (UTP), common telephone wire. It is based
on a star topology, where all communication goes through a
central point, the LAN's hub. Thus, network management tools
can be used to monitor and control network resources in ways
that are impossible with bus topologies.

10Base-2 refers to the IEEE standard for Thin Ethernet which
is also referred to as CheaperNet or CNet. It uses an RG58 coax
cable up to 200 meters in length for a single trunk segment.

10Base-5 refers to the IEEE standard for Thick Ethernet which
is also referred to as ENet. It uses an RG11 coax cable up to
500 meters in length for a single trunk segment.
ENIntroduced by Toshiba at the 1989 Spring Comdex, the 2.88 megabyte
drive doubles the amount of data storage available on the existing
high density 3.5" microdiskettes. The unformatted, blank capacity
is rated at 4.0 megabytes.

The additional data storage is accomplished by doubling the
number of sectors per track, from 18 to 36, or packing twice as
many bits on each track. This is achieved by recording the data up
and down (perpendicularly) rather than end to end along the track.

Toshiba's new proposed standard does not increase either the number
of tracks on the disk or the track density. Although this allows
existing head-positioning assemblies to be used, a 2.88 drive will
need a new head, supporting electronics, and a modified controller.

See the table "Floppy Disk Specifications" for an overview.
gIntroduced in 1986 by Sony Corporation, the 3.5" disk, often called
a microdiskette, is used for data storage on personal computers.

It provides significant design improvements over the conventional
5.25" floppy diskette. The smaller size and stronger container make
handling easier and safer. The actual magnetic disk surface is only
exposed when the disk is inserted in the drive. This reduces the
possibility of contamination by fingerprints and dust particles.

³ Storage ³ No. ³ No. ³ Sectors ³ Sector ³ Cluster ³ MS-DOS ³
³ Capacity ³ Heads ³ Tracks ³ /Track ³ Size ³ Size ³ Version ³
³ 720 K ³ 2 ³ 80 ³ 9 ³ 512 ³ 1024 ³ 3.2+ ³
³ 1.44 MB ³ 2 ³ 80 ³ 18 ³ 512 ³ 512 ³ 3.3+ ³
³ 2.88 MB ³ 2 ³ 80 ³ 36 ³ 512 ³ 512 ³ 3.3+ ³
òzWith versions of DOS prior to 4.0 there is a built-in limit on the
size of a disk partition. It's just a matter of arithmetic. Using
the original design parameters of DOS, we can show how the maximum
size disk partition is defined.

The facts: One word, 16 bits, is defined for DOS to access sectors
within its hard disk partition. A single 16-bit binary
word can represent values from zero through 65,535.
This limits the partition's total sector count to 65,536.
Hard disk sectors are 512 bytes long.

Now the arithmetic: 512 bytes times 65,536 sectors = 33,554,432
And since there are 1,048,576 bytes in each megabyte, the maximum
size partition calculates to exactly 32 megabytes.

×pA 360 K floppy is a magnetic diskette for storing and retrieving
electronic data and programs.

The 360 K floppy diskettes were introduced by IBM with the original
PC class machine. It has a data storage capacity of 360 kilobytes.
It is 5.25" in diameter.

A 360 K floppy diskette can be read and written to both with a
360 K drive and with the later model, high density 1.2 MB floppy
disk drives. Because the two disk drives and the diskettes appear
to be identical, this is often a confusing matter for beginners.

Generally, a PC or XT-class machine will have a 360 K floppy drive
while an AT-class machine will house a 1.2 MB floppy drive.

See the table "Floppy Disk Specifications" for an overview.
ãdA 4GL, Fourth Generation Language, refers to the most recent level
of programming languages whereby programs are written that consist of
commands from the application package which is written in a second or
third generation language.

dBase programs, Query languages, and report writers are good examples
of 4GL programs.

Although the terms 1GL, 2GL, and 3GL are rarely used, 1GL refers to
machine language programming, the lowest level computer language.

2GL refers to assembly language programming, and 3GL then refers to
all the third generation programming languages such as BASIC, COBOL,
FORTRAN, Pascal, C, Ada, etc. where the source code is compiled to
create an executable program file or application package.

4SIn the late 1970's when microcomputers first appeared, the only
means of storing programs and data off-line was on 5.25" floppy
diskettes. Hard disk drives had not yet been invented. The
original 5.25" disk drives were about three inches in height and
were housed in the computer in one of two bays.
³ Storage ³ No. ³ No. ³ Sectors ³ Sector ³ Cluster ³ DOS ³
³ Capacity ³ Heads ³ Tracks ³ /Track ³ Size ³ Size ³ Version ³
³ 160 K ³ 1 ³ 40 ³ 8 ³ 512 ³ 512 ³ ALL ³
³ 180 K ³ 1 ³ 40 ³ 9 ³ 512 ³ 1024 ³ 2.0+ ³
³ 320 K ³ 2 ³ 40 ³ 8 ³ 512 ³ 1024 ³ 1.1+ ³
³ 360 K ³ 2 ³ 40 ³ 9 ³ 512 ³ 1024 ³ 2.0+ ³
³ 1.2 MB ³ 2 ³ 80 ³ 15 ³ 512 ³ 512 ³ 3.0+ ³
Only the 360K and 1.2 MB (5.25") floppies are in common use today.
"oThe first-generation microcomputers utilizing the Intel 8088 or
8086 microprocessor chip were designed to address or manipulate
1,024 kilobytes of random access memory (RAM).

The designers figured that the lower 640 kilobytes of that 1,024K
would be sufficient memory for DOS and its applications. So that's
the way it was set-up. In the early to mid-1980's, when these
systems began to proliferate, most of them operated with only 256K
or 512K of memory (RAM), and the software applications then would
execute with memory to spare.

By the late 1980's, systems were rarely sold with less than 640K
of memory because the faster and more powerful programs had grown
in size. Many interesting "work-arounds" have been designed to
extend and/or expand memory beyond the 640K barrier.
6<A 720 K microdiskette is a magnetic diskette for storing and
retrieving electronic data and programs.

The 720 K microdiskette was introduced in the mid 1980's as a
3.5" diskette. It has a data storage capacity of 720 Kilobytes.

A 720 K microdiskette can be read and written to both with a
720 K drive and with the later model, high density 1.44 MB floppy
disk drives. Because the two disk drives and the diskettes appear
to be identical, this is often a confusing matter for beginners.

See the table "Floppy Disk Specifications" for an overview.
The 8514/A is an analog video display adapter from IBM for the
PS/2 line of personal computers. Compared to previous display
adapters such as EGA and VGA, it provides a high resolution of
1024x768 pixels with up to 256 colors or 64 shades of gray.

It is an interlaced monitor which means that it scans every other
line each time the screen is refreshed. It provides a video
co-processor that performs two dimensional graphics functions
internally, thus relieving the CPU of graphics tasks. The 8514/A
monitor improves the performance of CAD applications by as much as
ten times.

The IBM 8514 display system is a combination of the 16-inch
multiple-fixed-frequency 8514 monitor and the 8514/A graphics
adapter. They work together only in MCA systems.
p%A 9-Track tape is a reel of half-inch magnetic tape for storing
computer data.

9-Track tape reels are about 12 inches in diameter and are widely
used with mainframe and minicomputers. They are available in a
variety of tape lengths, such as 1200, 2400, and 3600 foot reels.

Depending on the capabilities of the tape drive, the data can be
recorded on the tape at 800 bytes per inch (800 BPI), or 1600 bytes
per inch (1600 BPI). The recording scheme places data on nine
separate parallel tracks, the 8 data bits of a byte plus 1 parity

Early magnetic tapes used a 7-Track recording scheme at 556 BPI.
O[An A/B switch is a hardware device that provides a junction in an
electrical cable so that the signals can be sent along one of two

This device is frequently used when two printers are connected to
one computer port. The operator can change the switch setting from
"A" to "B" depending on which printer is to be used.
@0When the execution of a program or task is terminated because of
an abnormal end or when the task is terminated by the operator
before its completion, the program is said to have been aborted.
Control is then returned to the operating system.

The term 'abend' (abnormal end) is sometimes used in place of abort.
Ó?An access code or a password is simply an identification number
or a set of characters that are sometimes required to gain entry
to a computer program or system.

It is often desirable for individuals and companies to protect
their valuable data or resources from unauthorized use.

However, the computer has no way of knowing whether the person
entering the password or code is legitimate or not, so always
protect your passwords and change them often.
çbThe time required for a memory device to produce a dependable
output signal after it receives an input signal requesting the
contents at an address is called its access time.

To take full advantage of the central processor's potential
speed, the memory chips should have access times fast enough
to function properly at the processor's optimal speed.

The access time for a storage device such as a disk is the
amount of time required to begin delivering data after the
CPU sends a data request. Since different operating
environments can affect access times, the figure given is
usually an average time. Benchmark tests will often measure
a system's access times.

See the reference table: "Microprocessor Clock Rates"
”An acronym is a word formed from the first or first few letters
of a series of words.

The following examples of acronyms are further discussed in this
PC-GLOSSARY program:

MODEM, from MOdulator-DEModulator

COBOL, from COmmon Business Oriented Language

FORTRAN, from FORmula TRANslator

WORM, from Write Once Read Many

NetBIOS, from Network Basic Input/Output System
CZA hub is a distribution, hardware device used in certain network
topologies to perform special functions with the transmission
signals. There are two types of network hubs, active and passive.

An active hub is used to amplify and condition the transmission
signals while allowing for additional workstation ports to be added.
Active hubs have between four and 64 ports.

A passive hub, often with just 4 ports, is also used to split a
transmission signal so that additional workstations can be added,
but a passive hub cannot amplify the signal. Passive hubs must
therefore be connected directly to a workstation or an active hub.

Local Area Networks using ARCnet topology have active and passive
hubs attached to achieve a maximum cabling distance of 20,000 feet
from any node on the network to any other node.
omThe dictionary defines ad hoc as Latin for 'to this', or for this
specific purpose; for a special case only.

An ad hoc query is a request or an inquiry for information to be
extracted from a database. It is initiated directly by a user, rather
than indirectly through an application program that provides menus or
other structures for formulating the query.
˜LAda is a high-level programming language developed in the late
1970's for the U.S. Department of Defense. It is intended
particularly for embedded systems and stresses modularity,
reliability, and maintainability. It bears a strong resemblance
to Pascal and was designed to improve programmer productivity by
allowing several tasks to be performed simultaneously. It is
very large and comprehensive.
Ada is named after Augusta Ada Byron, the Countess of LoveLace,
who is credited as being the first computer programmer. In the
mid-nineteenth century, she translated the description of Charles
Babbage's Analytical Engine into French. During the translation
she took many notes and wrote a series of instructions for the
machine to perform complex mathematical calculations.

NOTE: There are Ada compilers for the IBM-compatible PCs.
See the October '89 issue of Embedded Systems Programming
&TIn a network of computers, a routing technique that has the capability
of changing or re-defining a route while the transmission of data is
in progress is called adaptive or dynamic routing.

The route is typically modified in response to traffic congestion or
a hardware device failure.
"\Each location in computer memory is numbered consecutively. The
number is referred to as the location's address.

An address can be a label, name, or number that identifies a
particular register, an exact storage location in main memory, or
an external storage device.

After a computer program is written and compiled or assembled into
machine language, it can be loaded into the computer's memory where
it references actual addresses.

In another sense, each workstation or node in a network of computers
has a unique address.
}"AI" is the field of computer science that seeks to understand
and implement computer-based technology that can simulate the
characteristics of human intelligence. A common goal of artificial
intelligence work involves developing computer programs capable of
learning from experience in order to solve problems.

"AI" refers to the development or capability of a machine that can
proceed or perform functions that are normally concerned with human
intelligence, such as learning, adapting, reasoning, self-correction,
and automatic improvement.

In a more restricted sense, artificial intelligence refers to the
study of techniques for the more effective use of digital computers
by improved programming practices. PROLOG and Lisp are the most
popular programming languages for the development of non-numeric
programs, particularly in the field of Artificial Intelligence.
*0An acronym for ALGOrithmic Language, ALGOL is an international
high-level programming language used to code mathematical problems.

Originally developed in 1958 as a means of communicating theories
and concepts, it was not implemented until 1960 as ALGOL-60. The
last standard version of the language, ALGOL-68, corrected many of
its earlier deficiencies. ALGOL was popular in Europe.

Although it is essentially a "dead" language, ALGOL has had a strong
impact on program language design and managed to spawn others, most
notably Pascal.
An algorithm is a formal procedure that always produces a correct
or optimal result. It applies a step-by-step procedure that
guarantees a specific outcome or solves a specific problem.

It is a predetermined set of instructions for solving a specific
mathematical problem in a finite number of steps.

Devising algorithms and proving their correctness is an important
part of computer programming.
}dWhen a new product is released for testing to a company's own
employees before exposing it outside the company, the product is
said to be under alpha testing.

Beta testing then is the pre-testing of hardware or software
products with selected typical customers to discover inadequate
features or possible product enhancements before it is released
to the general public.
ÓlThe term alphanumeric refers to data or terms that consists of
both numbers and alphabetic characters.

Examples of alphanumeric terms:

WD40, 5IVE, 2x4, R2D2, RU469, ICU812, OCT90, 1040EZ
ˆ The ALU is the heart of the microprocessor, and one of the essential
components. It is the operative base between the registers and the
control block. It performs various forms of addition, subtraction,
and the extension of these to multiplication, division, exponentiation.
The logic mode relates to the operations of gating, masking, and
other manipulations of the contents of the registers.

Generally, ALU architecture handles 8-bit quantities through the
accumulator while the register file is composed of three 16-bit
registers. Because the accumulator and the ALU are often only 8
bits wide, these three general registers can be accessed by
instructions that treat them as six 8-bit registers. The choice of
concept is often up to the programmer. From a hardware standpoint,
the processor on many systems operates on 8-bit bytes and all I/O
operations use an 8-bit data path.
Í!There are two main ways of doing things electronically, analog or

In the analog method, signals are continuously variable and the
slightest change may be significant. Analog circuits are subject
to drift, distortion, and noise, but they are capable of handling
complex signals with relatively simple circuitry.

Analog data transmissions require amplifiers, due to attenuation
of the signal with distance, to boost or magnify the signal.
pbANSI is an abbreviation for American National Standards Institute.

It is a non-governmental organization founded in 1918 that proposes,
modifies, approves, and publishes data processing standards for
voluntary use in the United States.

ANSI is also the U.S. representative to the International Standards
Organization (ISO) in Paris, and the International Electrotechnical
commission (IEC).

Any programming language that claims to conform to ANSI standards
must pass all the tests for the standard syntax rules as set forth
by ANSI.

For more information contact ANSI, 1430 Broadway, New York, NY 10018
GStatic electricity that builds-up on your body can be harmful to
electronic components. If you plan to work inside the case of your
computer, or with printed circuit boards, always insure that you
are properly grounded.

Anti-static products work in one of two ways: by helping prevent
static buildup or by providing a convenient and safe means of
draining the charge. In general, static drainage products are much
more effective than static control products.

Static control products include ungrounded floor mats, CRT screens,
spray cleaners and wipes, and equipment dust covers.

Static drainage products, which have a ground that ultimately ends
in the earth, include grounded floor mats, dust covers, anti-glare
screens, touch pads, desk pads, and some surge protectors.
kIn computer graphics, when lines are drawn at an angle their
appearance often takes on a jagged or stair-step effect. This
is especially true on monitors with a poor resolution and is
referred to as aliasing.

Antialiasing is a desirable feature in a computer graphics system
whereby the jagged or stair-step effect is automatically removed
or reduced.
JRAmerica Online is an on-line service with a graphical interface
started in 1988 for Apple and MacIntosh computers. In February of
1991, the PC version became available with EGA resolution.

Services include: electronic mail, headline news, weather, stock
market quotes, downloadable games, special interest groups, bulletin
boards, on-line shopping, and limited research capabilities.

For current fees and more information:

America Online
Quantum Computer Services 703-448-8700
8619 Westwood Center Drive, #200 800-827-6364
Vienna, VA 22182-9806
ÒGAPI is an abbreviation for Application Program Interface.

APIs are the tools that program developers use to access the
functionality of a computer's operating system and the services of
its peripheral devices.

Generally, APIs are system calls, routines, that allow programmers
access to the services provided by the operating system. APIs
can be used to manipulate files and directories, provide record
locking and transaction tracking, semaphore control, interface to
graphics adapters, and a wide variety of other services.

On a Local Area Network, an API such as IBM's NetBIOS, provides
applications with a uniform means of requesting services from the
lower levels of the network operating system.
c<APL stands for "A Programming Language", which was the title of a
book written in 1962 by the creator of the language, Kenneth E.
Iverson. Based on what was originally referred to as Iverson
Notation, APL is an extremely concise programming language, designed
for the manipulation of arrays. The arrays may be scalars, vectors,
tables, or matrices of two or more dimensions, and may be composed
of either numeric or alphanumeric information. Under Iverson's
leadership, IBM introduced APL\360 in 1966.

Since APL predates the introduction of personal computers, it was
originally used only on mainframe computers. Since 1983, versions
of APL have been available for the PC. Because of its expanded
special character set, APL requires a special keyboard or macros
for data entry.

IBM's current mainframe and PC versions of APL are called APL2.
ÎIn the DOS environment, every disk file can have four attributes
or characteristics associated with it. The one called the archive
attribute is actually a bit which is set to one or zero depending
on the status of the file.

When the file is backed-up or archived the archive bit is set to
one and when the file is changed the archive bit is reset to zero.

The DOS ATTRIB command can be used to view and/or change the status
of a file's archive bit.
Ñ-To the true definition, an archive file is one that has been copied
onto an auxiliary storage medium such as disk or magnetic tape for
the purpose of long-term retention.

In the microcomputer world, an archive file is one that has been
compressed, squashed, squeezed, crunched, and/or packed with a file
archiving program in order to use less disk space and to reduce the
transfer time when sending files between computers.

Data Libraries store program and data files in compressed format and
rename the files using the ".ARC" or ".ZIP" filename extension.

For further information on the .ARC file compression and archiving
programs, write to:

System Enhancement Associates, Seattle, Washington
xhARCnet is a baseband, token-passing Local Area Network technology
offering a flexible topology for connecting personal computers.
The term ARCnet is an acronym for Attached Resource Computer network.
It is one of the oldest LAN technologies and was originally developed
by John Murphy of Datapoint Corp.

ARCnet interface cards (or network controller boards) are
manufactured by various vendors each having the capability of
functioning with other ARCnet cards. That is, each PC workstation
on a network could have an ARCnet card from a different
manufacturer (in a star topology).
LANs utilizing network interface cards are often referred to as
media-sharing and are more flexible and provide faster performance
than the RS-232 LANs. ARCnet LANs are capable of operating at speeds
up to 2.5 megabits/second.
IEEE 802.4 addresses the specifications for ARCnet cabling.
í/The American Standard Code for Information Interchange is a
standard seven-bit code that was created in 1965 by Robert W. Bemer
and established to achieve compatibility between various types of
data processing equipment. ASCII, pronounced "ask-key", is the
common code for microcomputer equipment.

The Standard ASCII Character Set consists of 128 decimal numbers
ranging from zero through 127 assigned to letters, numbers,
punctuation marks, and the most common special characters.

The Extended ASCII Character Set also consists of 128 decimal numbers
and ranges from 128 through 255 representing additional special,
mathematical, graphic, and foreign characters.

See the Reference Tables for the complete ASCII Character Sets.
rKAn ASCII text file is a data file containing only alphanumeric and
special characters that belong to the ASCII character sets.

ASCII text files can be read by most modern word processing programs
and then internally converted to another format so that special word
processing features can be utilized. For example, there is no
standard ASCII character that can be added to the beginning of a line
of text that causes that line to be centered when output to the
screen or to a printer. Each different word processing program may
have a special control character for centering text.

There are many different control characters utilized by different
application programs for enabling or identifying special features.
Files that contain these special control characters are not ASCII
text files, and can only be properly utilized by the program that
created them.
DWThe Association of Shareware Professionals is an organization of
programmers founded in 1987. The primary goal of the association
is to strengthen the future of shareware marketing as an alternative
to traditional marketing. The ASP is also striving to help diskette
vendors, the news media, and the general public to understand the
nature and benefits of shareware.

The major theme behind shareware programs is "Try before you buy".
Users can evaluate the program on their own systems before making
an investment. If the program proves to be useful, the user has
a moral and legal obligation to register with the author.

Address your written correspondence to: ASP, 545 Grover Road
Muskegon, MI 49442

On CompuServe, GO SHARE, for public and private ASP forums.
'Generally speaking, each design of computer whether it be an
IBM, Honeywell, Digital, or any other, has its own assembly

Assembly language is a low-level programming language that uses
mnemonic instructions, such as STO for store and SUB for subtract,
instead of binary numbers to represent the corresponding machine
language instruction.

It is written to correspond to a specific computer's machine language.

An assembler is a program that translates the assembly language
symbolic code into its equivalent machine code.
SThe asterisk is a character widely used in programming languages
to indicate multiplication, such as 3 * 3.

The asterisk is also used as an acceptable character in the syntax
of a command line argument as a wildcard to represent one or more
other characters.

For example, consider the following DOS command line; DIR *.*
The argument part, the *.* (star-dot-star) is used to indicate any
combination of filename and file extension.

The asterisk is known by other names such as star, splat, gear,
mult, wildcard, and dingle.
Å`When signals are sent to a computer at irregular intervals, they
are described as asynchronous.

When data is transmitted asynchronously, it is sent at irregular
intervals by preceding each character with a start bit and
following it with a stop bit.

Asynchronous transmission allows a character to be sent at random
after the preceding character has been sent, without regard to any
timing device. Contrast with synchronous transmission.
clThe set of commands that is used to control the operation of a modem
is called the standard Hayes AT Command Set. Most of the commands
are prefaced with an AT which stands for ATtention.

For example, to dial the phone, the communications program would send
the command "ATD" (ATtention, Dial) to the modem.

In 1981, Hayes Microcomputer Products, Inc. produced the first modem
to operate with a command set. It was called a smart modem because
prior to that time modems only modulated and demodulated signals
between the telephone line and the computer. They did not operate with
a command set.
O!ATM is an abbreviation for Automatic Teller Machine.

Modern banking facilities provide ATMs as a service to their customers
so that deposits and withdrawals can be made at all hours often from
terminals remotely located from the bank. An ATM can be a stand-alone
unit or connected directly to the central computer system. The
customer activates a transaction by inserting a plastic card into the
terminal. The card contains a magnetic strip with the customer's
account information.

ATM is also an abbreviation for Asynchronous Transfer Mode, an emerging
standard for cell-based data transport on high-speed LANs. The basic
packet is a fixed-length cell of 53 octets (bytes), 5 of which are used
for control functions and 48 for data. This permits digitized voice to
be transmitted as packets beginning at speeds of 155 Mbps.
ú\An attribute is a characteristic that describes data, or a data
structure, or an element of a data model.

An attribute is a word that describes the manner in which a
variable is handled by the computer.

For example, typical file attributes would be the file's size and
the length of a record in a file.

The DOS file attributes are stored in byte 11 of a directory entry
and determine whether or not a file is declared read-only, hidden,
a system file, or if the archive bit is on or off.
•In computer-related operations, an audit trail is data in the form
of a logical path linking a sequence of events. This data is used
to trace or examine the transactions that have affected the
contents of a database.
In an accounting system, an audit trail may be automatically
maintained by a special program feature. Pointers or records of
transactions are stored so that the origin of specific figures can
be easily identified.
Network operating system software often includes a feature for
maintaining an audit trail of events that take place throughout
the network. It can be as simple as maintaining a log of who,
when, where, and how long an individual was connected to the
network. Or an elaborate audit trail can be activated which will
keep records of almost every imaginable event. The level of
sophistication depends on the network operating system and the
needs of the organization.
The AUI is an IEEE 802.3 standard designation for the cable that
connects workstations on a local area network often using thick
Ethernet cable. It is the interface between the medium attachment
unit (MAU) and the data terminal equipment (DTE).

The IEEE specification 10Base-5 is shorthand for a 10 megabits per
second baseband medium with a maximum segment or trunk length of
500 meters.
z[The AUTOEXEC.BAT file is an operating system file that DOS searches for
each time the microcomputer is booted. It is not required but provides
many advantages. DOS only looks for it in the root directory of the
boot device (either the A: floppy drive or the C: hard drive).

The AUTOEXEC.BAT file is an ASCII text file and can be changed with
any text editor program such as EDLIN.

Since the DOS commands in the AUTOEXEC.BAT are executed each time the
system is booted, the operating environment for each particular system
can be optimized to take advantage of the attached hardware.

Software applications that reside on the hard disk often require that
certain parameters be defined in the DOS environment space. These SET
commands can be placed in the AUTOEXEC.BAT file. If you have never seen
one, at the C:\ prompt, enter the following command, TYPE AUTOEXEC.BAT
uTWhen the hard disk drive is not in use the read/write heads are
locked in their current position as a safety measure, but not
necessarily away from critical areas of the disk platter(s).

A hard disk drive feature that does ensure the read/write heads to
be securely parked away from all critical areas of the platter is
called automatic park. This feature is implemented whenever power
is turned off or lost.

Most hard drives that offer the automatic park feature use voice-
coil technology.

The mechanism that lifts the heads away from the platter when
power is removed is called the automatic head lifter.
# AWG is an abbreviation for American Wire Gauge.

It is a system for the measurement of the thickness of metal wire.
The gauge number increases as the wire diameter decreases.

For example, AWG number 10 has a diameter of 0.102 inches and
AWG number 29 has a diameter of 0.011 inches.
; A popular European typewriter or computer keyboard, with the
characters "A, Z, E, R, T, and Y" as shown below. There are many
other different keyboard styles in use throughout Europe.

³ ³³ A ³³ Z ³³ E ³³ R ³³ T ³³ Y ³³ U ³³ I ³³ O ³³ P ³³ ³³ ³³ ³
³ ³³ Q ³³ S ³³ D ³³ F ³³ G ³³ H ³³ J ³³ K ³³ L ³³ M ³³ ³³ ³
³ ³³ W ³³ X ³³ C ³³ V ³³ B ³³ N ³³ ³³ ³³ ³³ ³³ ³
³ ³³ SPACE BAR ³³ ³
^AA backbone network is a communication facility that is used to connect
two or more networks. It normally operates at a significantly higher
speed than the networks or file servers that it connects and may be of
a different topolgy and use different protocols.

Typically, user workstations are not connected directly to the network
ÕThe background mode is the teleprocessing or multi-programming
environment in which lower priority tasks are processed during
a time when higher priority tasks are inactive.

In a multitasking environment, to control a program operating in
the background, it must be brought to the foreground with
operating system commands. A background program, such as a
printing task, is executed when a higher priority task is inactive.

The foreground mode is the teleprocessing or multiprogramming
environment in which high priority tasks are performed before
those of a lower priority.

Generally, there may be several background operations running, but
only one foreground operation running, at any given instant.
Ÿ;Copies of data and program files are called backups.

It is always advisable to make backups of your data and programs.
Microcomputers, like all things manufactured, are prey to human
error and mechanical failure.

No matter what type of backup hardware you choose, you still need
a backup system, a strict routine for making backups.

Most backup systems fit into one of two categories; tape or disk.
íA balun transformer is a connector that allows balanced cables to
to be joined together with unbalanced cables. The electrical
characteristics of each are matched so that data can be transmitted.

For example, twisted pair (balanced) cables can be joined with
unbalanced coaxial cable if the proper balun transformer is used.

In an ARCnet local area network, in-line baluns can be used to
convert the impedance of coaxial cable so that its signal can run
on twisted-pair wiring.
;&Generally, bandwidth is a measure of the range of frequencies
within a radiation band required to transmit a particular signal.

It measures, in millions of cycles per second, the difference
between the lowest and highest signal frequencies.

The bandwidth of a computer monitor is a measure of the rate that
a monitor can handle information from the display adapter.

The wider the bandwidth, the more information the monitor can
carry, and the greater the resolution. For example, the CGA
monitor which has a poor resolution, has a bandwidth of 30 MHz.
8zAs the name implies, Bar code is the code used on consumer products
and inventory parts for identification purposes. The code is read
with an optical wand or a stationary in-counter bar-code reader.
The code consists of bars of varying thicknesses to represent
characters and numerals. There are several product-marking codes,
such as Universal Product Code (UPC), CODABAR, and MSI.

A sample of a Bar code: º³Ûººº³Û³Ûºº³Û³º³ºº³Û³

As a point of interest, the city of Treasure Island, Florida sells
bar code decals at the toll bridge for car windows so that residents
can pass through toll free.
Baseband signaling is a method or technique for transmitting
digital data at speeds of up to 10 million bits per second.

Baseband transmission uses low-frequency signals over coaxial
cable or twisted pair, limited in distance to less than 2000 feet.

ARCnet and Ethernet local area networks utilize baseband signaling.

Baseband handles digital data only, is relatively easy to install
and modify, and is less expensive than broadband signaling which
handles voice, data, video, and image transmissions over a greater
ÓEBASIC is a computer programming language, an acronym for

Beginner's All-purpose Symbolic Instruction Code.

Although it is a simple language to learn and use, it contains many
advanced features for handling mathematical formulas and character
strings. It is an interpretive language which means that each
statement is translated and executed as it is encountered rather
than having all the program statements compiled before execution.

There are compilers for BASIC so that final versions of programs can
be translated to executable code for faster run-time performance.

BASIC was originally developed by John Kemeny and Thomas Kurtz in
the mid-1960's at Dartmouth College in Hanover, New Hampshire.
³MA batch file is a set of commands which are stored in a disk file
for execution by the operating system.

Typically, a batch file is created to save time and reduce the
possibility of error for tasks that are executed frequently.

Personal computer users create a batch file called AUTOEXEC.BAT
which is automatically executed by DOS each time the system is

DOS batch files utilize the .BAT filename extension.
ÉVThere are electronic components on printed circuit boards of
most microcomputers that need a constant supply of electrical
energy in order to retain their stored information.

One such component is the clock/calendar. It is kept active
with dry cell batteries or with coin-shaped lithium batteries.

When these batteries deteriorate and lose their power, the system
clock fails to keep the correct time and date. Rather than input
the correct time and date when the system is booted, it would be
easier to simply replace the batteries.

When this system set-up and timing information is retained by the
use of a small battery inside the computer, the computer is said
to have 'battery backup'.
…The word baud is derived from the surname of J.M.E. Baudot
(1845-1903), a French pioneer in the field of printing telegraphy
and the inventor of the Baudot code.

Baud is a unit of measurement that denotes the number of discrete
signal elements, such as bits, that can be transmitted per second.
Bits per second (bps) means the number of binary digits transmitted
in one second. There is a difference between bps and baud rate, and
the two are often confused. For example, a device such as a modem
said to transmit at 2400 baud is not correct, it actually transmits
2400 bits per second.
It is important to note that both baud rate and bps refer to the
rate at which the bits within a single frame are transmitted. The
gaps between the frames can be of variable length. Accordingly,
neither baud rate nor bps refers to the rate at which information
is actually being transferred.
Ò!A bulletin board system is a computer that operates with a program
and a modem to allow other computers with modems to communicate with
it, often on a round the clock basis.
There are thousands of MS-DOS and PC-related bulletin board systems
in the United States offering a wealth of information including
libraries of shareware programs that can be downloaded.

Most BBSs fall into one of five distinct categories. The general
interest BBS caters to a large audience, with message bases devoted
to several topics, a generous supply of shareware software, news,
and entertainment. The technical BBS deals with questions about DOS,
hardware and programming. System specific boards focus on some
particular brand of computer system and contain compatibility tips
and information on related issues. Special interest BBSs offer info
on non-computer subjects. Other boards exist primarily as sources
for the many shareware programs in their libraries of files.
è6BCD, an acronym for Binary Coded Decimal, is a type of
positional value code in which each decimal digit is binary coded
into 4-bit "words".

BCD is based on, and sometimes called, the 8421 code. It derives
its name from the value assigned to each of four bit positions,
with each set of four bits equal to one decimal. The decimal number
12, for example, would become 0001 0010 in BCD.
³ Decimal ³ 8421 Binary ³ ³ Decimal ³ 8421 Binary ³
³ 0 ³ 0000 ³ ³ 5 ³ 0101 ³
³ 1 ³ 0001 ³ ³ 6 ³ 0110 ³
³ 2 ³ 0010 ³ ³ 7 ³ 0111 ³
³ 3 ³ 0011 ³ ³ 8 ³ 1000 ³
³ 4 ³ 0100 ³ ³ 9 ³ 1001 ³
ûsIn a token-ring network, when an adapter detects a hardware failure
on the ring, it broadcasts a frame with a message informing other
stations that the token passing has been suspended. The message or
frame is called a beacon.

The term broadcast storm is often used to describe a situation on a
token-ring network when a device is not communicating properly and
causes an excessive amount of traffic to be generated. This in turn
causes the network response time at the workstation to increase.
¤;This list of standard AT&T Bell modems are the most popular models.
Corresponding CCITT Recommendations are listed in parenthesis.

Bell 103 - Asynchronous at 300 bps, full duplex, FDX. (V.21)

Bell 212A - Asynchronous at 300 bps, synchronous at 1200 bps, FDX.

Bell 201 - Synchronous at 2400 bps, half duplex on 2-wire dial-up,
(V.26) full duplex on 4-wire leased line.

Bell 208 - Synchronous at 4800 bps, half duplex on 2-wire dial-up.
(V.27) FDX on 4-wire leased line. Fall-back rate is 2400 bps.

Bell 209 - Synchronous at 9600 bps, full duplex requires 4-wire
(V.29) leased line. Fall-back rates are 7200 and 4800 bps.
wZA benchmark is a process or program that can be executed to measure
and compare the performance of one system against another.

Testing the relative performance of microcomputer systems must deal
with the problem of different CPUs, different FPUs, and different
operating systems. Benchmark tests should be designed on some sort
of common ground so that the results present a true measure of
system performance even across brandnames and architectures.

There should be low-level tests to measure floating point operations
and application-level tests to measure things like the speed of
spreadsheet re-calculations.
ºA flexible disk storage system that rivals hard disks for data
capacity and access speed.

The technology is based on the principles of aerodynamics that
Daniel Bernoulli discovered in the 18th century. In the early
1980's, Iomega Corp. introduced the Bernoulli Box, which uses
replaceable 8-inch or 5.25" disk cartridges.

The removable Bernoulli drive cartridges can be used to backup
a hard drive or in place of a hard drive.
rThe base-2 number system in which only the digits 1 and 0 are used
is referred to as the binary system.

The base-2 or binary system lets us express any number, if we have
enough bits, as a combination of 1's and 0's. Because these digits
can be used to represent two states, on and off or true and false,
which in turn can be represented by two voltage levels in an
electronic device, the binary system is at the heart of digital

Binary numbers are typically written as four-digit combinations.

áyThe Basic Input/Output System, resident on a chip which plugs into
the motherboard of a microcomputer, is a system program.

The BIOS is responsible for handling the details of the input and
output operations, including the task of relating a program's
logical records to a peripheral device's physical records.

The BIOS contains routines tailored to the specific requirements
of each peripheral device. These routines are called drivers,
or device handlers.

As an example, a video BIOS consists of instructions on ROM that
interpret and execute video requests from applications software.
The BIOS executes these software requests by interacting with the
video memory registers, the CPU, and the monitor or printer.
I6Bit is an abbreviation for Binary digit

Computer words and data are made-up of bits, the smallest unit of
information. Most personal computers operate with 16-bit words.

A bit can be either zero or one, represented in a circuit by an
off or on state, respectively. The bits are set on or off to
store data or to form a code which in turn sends instructions to
the central processing unit.

The term 'bit' was reportedly first used in 1946 by American
John Tukey, a leading statistician and presidential advisor.

Two bits is still a quarter, a quarter of a byte.
uA method of storing graphics information in memory. A bit
devoted to each pixel (picture element) on the screen indicates
whether that pixel is on or off.

A bit-map contains a bit for each point or dot on a video display
screen and allows for very fine resolution since any point or
pixel on the screen can be addressed.

A byte of information, for example, could describe the appearance
of eight pixels. A greater number of bits could be used to
describe each pixel's color, intensity, and other display
á<BIX is an on-line service provided by BYTE magazine, published by
McGraw-Hill, Inc.

Services include: Industry news, downloadable software, powerful
electronic mail, previews of upcoming BYTE articles, the full text of
published issues of BYTE magazine, conferences on computer-related
topics, and source code for BYTE benchmarks and non-commercial
software mentioned in featured articles.

For current fees and more information, call

800-227-2983 or 603-924-7681
(RBritish National Connector is a nickname for the BNC connector.
BNC actually is an abbreviation for Bayonet Neill-Concelman.
The term bayonet describes the push and turn action necessary to
lock the male and female parts together. Mr. Neill-Concelman
invented it.

Originally designed in England for television set antennas, the
BNC is a type of connector designed for use with coaxial cabling.
They lock together when the male part is inserted into the female
part and rotated 90 degrees to lock it in place.

In the mid-1950's, the BNC became popular with military avionics
equipment, especially common in VHF and UHF radio communications.
Today, BNC connectors are very popular in Local Area Networks for
connecting microcomputers together and are used in both Ethernet
and ARCnet LANs.
]BoCoEx - Boston Computer Exchange, 1-617-542-4414,
Boston, MA

NACOMEX - National Computer Exchange, 1-212-614-0700,
New York, NY

Both of these organizations are computerized brokerage
firms publishing daily lists of used computer prices.
b0BOF and TOF are abbreviations for the Beginning or Top of File.
They are codes placed by a program before the first byte in a file
and are used by the computer's operating system to keep track of
locations within a file with respect to the first byte or character
in the file.

On disk, a data directory or catalog usually contains the location
of a file based on the file's BOF or TOF relative to the first
storage location on the disk. In an indexed database, the BOF or TOF
marks the first indexed record.

An EOF, End of File, is a code that marks the true end of a file.
Since disk space is allocated in blocks of bytes, the EOF code is
used to identify the actual point at which a file ends rather than
the end of the data in the file. The EOF mark is represented by the
ASCII code decimal value 26 or hexadecimal 1A, or Control-Z character.
53Boolean algebra is a deductive system or process of reasoning named
after George Boole, an English mathematician (1815-1864). It is a
system of theorems which uses symbolic logic to denote classes of
elements, true or false propositions, and on-off logic circuit elements.
It is fundamental to computers; all digital computers use the two-state
or two variable Boolean algebra in construction and operation.

The Boolean operators, which are also called logical operators, are

AND (conjunction) accepts two inputs, both must be one (or true) to
produce an output of one (or true).

OR (inclusion) accepts two inputs, either one or both inputs must be
one (or true) to produce an output of one (or true).

NOT (negation) reverses the input, one's become zero's.
»sA computer's operating system is initiated with a boot procedure,
a start-up from scratch.
For personal computers using DOS, when power is applied the CPU
initializes itself and reads the code stored in a read-only memory
chip, called the ROM BIOS. After some hardware initialization, the
boot-loader program loads one program from disk which occupies the
first file position and must be the first entry in the boot disk's
root directory. That program is usually called IO.SYS.

IO.SYS (or IBMBIO.COM) finishes initializing the hardware and loads
the Disk Operating System. DOS reads a file called CONFIG.SYS, if it
exists, and carries out the commands it contains, such as modifying
internal DOS tables and/or loading and initializing device drivers.
COMMAND.COM is loaded next which executes each line of the
AUTOEXEC.BAT file, if it exists, and finally displays a prompt
string on the screen waiting for the user to enter a command.
tnIn local area networks, a bridge is an interconnection device
between two networks of the same type using similar or dissimilar
data links such as Ethernet, token-ring, and X.25. Bridges function
at the data link layer of the OSI model.

Specifically, bridges operate at the media access control or MAC
sublayer of the data link layer. For this reason they are often
called MAC-layer bridges.
A bridge monitors all traffic on the two subnets that it links. If
a bridge links LANs that have dissimilar MAC layers, it does the
processing necessary to change, for example, an Ethernet packet to
a token-ring packet.
An internal bridge resides within the file server. An external
bridge is located in a workstation apart from the host or server.
External bridges may be dedicated or non-dedicated. When a computer
is used only as a bridge, it is a dedicated bridge.
ÛXGenerally, in data communications, both terms broadband and
wideband are used to describe transmission facilities capable of
handling frequencies greater than those required for voice grade
communications, ie. baseband.

Broadband communication channels can transmit data, voice, and
video signals at rates up to five million bits per second over long
distances using high frequencies.

Broadband transmissions require modems for connecting terminals and
computers to the network. Using frequency division multiplexing,
just like cable TV, many different signals or sets of data can be
transmitted simultaneously.

Compare broadband to baseband signaling which transmits at lower
speeds over shorter distances.
:Memory in which magnetic regions are suspended in crystal film
is called bubble memory. It maintains its data when the power
is off, and is therefore referred to as non-volatile read/write

A typical bubble memory device may contain up to 4 million bits
or bubbles, that's 500,000 bytes. One or more such devices may
be combined with special interface logic to form a bubble memory
system with an information access time of several milliseconds.

Because bubble memory systems require relatively little power and
retain information even when power is removed, they are sometimes
used as disk drive replacements in portable computers. Bubble
memory is also commonly used as solid-state "disk" drives in
environments where conventional, electromechanical drives are
unacceptable, such as factories.
ñ4A buffer is often a block of memory that the operating system uses
to temporarily store data. Several buffers can be defined at system
configuration time based on your applications.

The DOS configuration file called CONFIG.SYS, which is read when the
system is booted, can include a BUFFERS command line to set aside a
number of memory blocks for temporary data storage. If the directory
structure is large, the number of buffers should be set to about 30.

A buffer can also be part of a peripheral device containing its own
memory to receive the output of a task quicker than the device can
perform the task's instructions, thus freeing the processor for
other operations. Modern printers are designed and built with print
ÎAn error or mistake in a program, or a hardware malfunction in a
computer system is referred to as a bug.

Debug refers to the act of tracing and correcting errors in
programming code or resolving hardware malfunctions in a computer

The first real computer bug was found trapped in one of the
thousands of electromechanical relays inside the Mark I computer at
Harvard University in the 1940's. U.S. Navy officer Grace Murray
Hopper found the remains of a moth blocking an electrical switch.
The incident was documented with an entry in the logbook along with
the moth. From then on, the term "debugging" was used to describe
the process of finding the cause of errors in computer programs.
ê#In the world of computers, a bus is a set of wires or lines used for
data transfer among the various components of a computer system.
Actually, the bus is made up of traces on the printed circuit boards.

All the major components such as the microprocessor, the disk drive
controller, random access memory, and the input/output ports are
electrically connected by the bus so that information can be passed.

The first IBM microcomputers and compatibles such as the PC and the
PC-XT (8086 and the 8088) utilize an 8-bit data bus.

The IBM-AT (80286) systems provide both the 8-bit and the 16-bit bus.

Systems with the 80386 and 80486 microprocessors can transfer data
along a 32-bit bus, 32 bits of data are sent at the same time.
ðA byte is most often defined as 8 bits of data.

The largest decimal number that can be stored in one byte is 255,
that would be with all eight bits set to 1.

Even with computers that operate with 32 or 36 bit words, the
term byte still refers to 8 bits of data.

In 1964, the 8-bit byte became a standard with the IBM 360 computer.

Half a byte is a nibble or nybble, 4 bits.
Two bits is a still a quarter, a quarter of a byte.

See the Conversion Table "Bytes to Terabytes"
úhThe C-Language is the structured, modular, compiled, general-
purpose programming language traditionally used for systems
programming. It is referred to both as a low-level language
and as a middle-level language. It is portable or generally
machine independent which means that programs written in 'C'
can be easily transferred between different computers.

The C-Language has been closely associated with the UNIX
operating system, since it was developed on that system,
and since UNIX and its application software are written in 'C'.

'C' was originally designed and written by Dennis M. Ritchie.
The most widely known description of 'C' is found in

The C Programming Language,
by Brian W. Kernighan and Dennis M. Ritchie (Prentice-Hall)
"?A cache is a memory medium that provides faster access than the
medium where the data is customarily stored.

A cache memory architecture combines SRAM's speed with DRAM's
cost effectiveness. It provides a small amount (usually 64KB
or less) of fast SRAM (the cache) that is logically located
between the processor and main memory (which is usually
simple DRAM.)

A cache memory system is relatively expensive because it
requires SRAM chips for the cache and complex cache control
circuitry to regulate the operation of the cache.
¼8A computer program that aids in the design and drawing of a project
is referred to as CAD software.

Vast libraries of images are available at reasonable prices and CAD
software makes it easy to modify them for a specific purpose.
Because CAD drawings are recorded as lines and arcs, with mathematical
coordinates for the start and stop points, they are accurate and can
be reproduced at any size or scale without losing quality. When a
change is made, the relationship to all other elements in the drawing
remains constant.

CAD files are easily transferred between different software packages
and computer systems. Most publishers have adopted AutoCAD's .DXF
file transfer format.
˜The National Institute for Occupational Safety and Health reports
that thousands of Americans, most of them heavy keyboard users,
suffer from a painful hand injury called Carpal Tunnel Syndrome.

CTS gets its name from the narrow tunnel in the wrist connecting
ligament and bone. The median nerve, which carries impulses from
the brain to the hand, and the tendons that open and close the hand
are found in the carpal tunnel. When undue pressure is put on the
tendons, they can swell and compress the median nerve, causing
numbness, weakness, tingling, and burning in the fingers and hands.

A principal cause of CTS is stiff, static wrist position. You can
prevent CTS by placing your keyboard so that 90-degree angles are
formed at the elbows with your arms held loosely at your sides.
Take time to shake out your hands and arms when they feel tired,
and try not to punch the keys too forcefully.
When modems are used to send data between computers, the sending
modem transmits a high pitched tone (the carrier) to the receiving
modem. When the receiving modem detects this tone, a carrier detect
signal is returned to the sending modem.

The carrier detect signal is defined in the RS-232 specification
and is the same as the Received Line Signal Detector. It is a
modem interface signal that indicates to the attached data terminal
equipment (DTE) that it is receiving a signal from the distant
=CASE, or Computer-Aided Software Engineering, can be defined as
software automation. It is a tool for programmers, analysts, and
systems engineers.

CASE provides software tools and utilities to help corporate
planners plan, and to document their work; to support systems
analysts in analyzing and designing systems, and to document those

Prior to the late 1980's, CASE software packages were mostly
available only on mainframe computers, and their cost were in the
five- and six-figure price range. Now the majority of them run on
ÍzComit‚ Consultatif International T‚l‚graphique et T‚l‚phonique

The CCITT is an international consultative committee, organized
by the United Nations. It makes recommendations for international
communications, which are frequently adopted as standards. It also
develops interface, modem, and data network recommendations.

Membership includes governmental Post, Telephone, and Telegraph
Authorities, scientific and trade associations, and private
companies. CCITT is part of the International Telecommunications
Union, a United Nations treaty organization in Geneva, Switzerland.

The popular standard X.25 protocol for access to packet-switched
networks was originally a recommendation of CCITT.
yCD-I is a specification for a complete hardware/software product
that includes a CD-ROM player, a Motorola 68000-family CPU, and
special audio and video processing hardware.

CD-I is an extension of CD-ROM that allows sound and video images
to be stored as standard analog signals alongside other digital

Although CD-I has a wide range of capabilities, including audio
with compact disk quality, it cannot display continuous full-screen,
full-motion video, and it cannot run on hardware that doesn't
precisely conform to the specification.

The CD-I concept was introduced in 1986 by Philips and Sony.
ÂA CD-ROM is a computer peripheral device that employs compact disc
(CD) technology to store large amounts of data for later retrieval.
Philips and Sony developed CD-ROM in 1983.

As a read-only data storage medium, CD-ROM disks can store digitized
text, data, images, and sound. They are stamped, like record albums,
from a metal master. CD-ROM disks are by definition unerasable and
incapable of being written to by the user. Current CD-ROM discs can
hold 680 megabytes of information. That's the equivalent of more than
275,000 printed pages of text, or 74 minutes of audio, or more than
1800 double-density 360K diskettes.
Although CD-ROM drives access data randomly, their typical data
transfer rate is an unimpressive 1.2 Mbits per second, substantially
less than the 5 Mbits per second data transfer rate of most common
hard disks. The physical controller interface for CD-ROM drives
varies, but the popular SCSI is clearly dominant.
OWith respect to spreadsheet operations, a cell is one individual
element of the matrix that makes up the spreadsheet.

Each cell of a spreadsheet has an address consisting of its row and
column. For example, cell "B9" is the rectangular area formed at
the intersection of row "B" and column "9". Cells can contain a
numerical constant, a formula, or a label.

If a formula is placed in a cell, the spreadsheet program will
display the results of the formula rather than the formula itself.

The cell format determines how values and labels are displayed.
For example, a worksheet dealing with financial figures may take
advantage of a global currency format. Each cell value would be
displayed with the dollar sign ($) and 2 places to the right of
the decimal point.
s3As a type of data transfer, the Centronics parallel format is an
unofficial standard. Almost without exception, a parallel interface
in a microcomputer printer will be a Centronics interface.
It was developed by the Centronics Data Computer Corporation in the
early days of microcomputing, and because of its usefulness, became
a de facto standard. Data is transferred 8 bits at a time.

The printer and the CPU communicate using three handshaking lines:
Data Strobe, Acknowledge, and Busy. A block of RAM in the printer
acts as a buffer or temporary storage for the data. The larger the
buffer, the more data the printer can accept before sending the Busy
signal to the CPU.

The disadvantage to the parallel Centronics system of data transfer
is the fact that parallel cables longer than about ten feet tend to
be sensitive to electrical noise or interference.
XThe Color Graphics Adapter was IBM's first color adapter for the
personal computer. It is compatible with red-green-blue (RGB)
monitors, color composite and monochrome composite monitors as
well as with standard television sets that have RF modulators.

CGA produces characters with an 8 by 8 pixel dot box and
graphics in two modes: medium and high resolution.

The CGA operates at a horizontal scanning frequency of 15.75 KHz.

A monitor must have a bandwidth of at least 14 MHz to be
compatible with the CGA.

Compared to today's EGA and VGA monitors, the CGA is poor quality.
ólA chip is an integrated circuit created on a tiny silicon flake
upon which a large number of gates and the paths connecting them
are formed by very thin films of metal acting as wires.

The chip can be used as main memory or as the CPU. When both
memory and logic capabilities are contained on the same chip,
it is called a microprocessor or a computer on a chip.

The chip consumes very little power, is compact, inexpensive,
and can process a million or more instructions per second.
vCompuServe Information Service is the name of the company that
provides an on-line service called CompuServe. It is one of the
largest in the world and is a text-based system operated on a
mainframe computer.

Services include: libraries of downloadable programs and data,
electronic mail with a gateway to other systems, hundreds of
conferences called forums for special interest groups, electronic
shopping mall, multi-player games, and research capabilities.

For current fees and more information,

CompuServe Information Service, 800-848-8199
P.O. Box 20212
5000 Arlington Centre Blvd.
Columbus, OH 43220
Pronounced "sisk", CISC refers to traditional computers that operate
with large sets of instructions. Most modern computers fall into
this category, including the IBM-compatible microcomputers.

As computing technology evolved, instruction sets expanded to
include newer instructions which are complex in nature and
require several to many execution cycles and, therefore, more
time to complete. Computers that operate with system software
based on these instruction sets have been referred to as complex
instruction set computers (CISC).

Contrast with RISC (Reduced Instruction Set Computer) computers,
which have far fewer instructions.
†#The verb "to click" refers to the depressing of the button or
buttons of a mouse.

Computer programs that interface with the operator through the use
of a handheld mouse device allow the user to make choices on the
screen by moving the cursor into a defined area and clicking a
mouse button.

A double click refers to the pressing of a mouse button twice in
rapid succession.
¥P"Client-server" is a term used in a broad sense to refer to the
relationship between the receiver and the provider of a service.

In today's world of microcomputers, the term client-server refers
to a networked system where front-end applications, as the client,
make service requests upon another networked system. Client-server
relationships are primarily defined by software.

In a local area network, the workstation is the client and the
file server is the server. But client-server systems are inherently
more complex than file server systems. Two disparate programs must
work in tandem, and there are many more decisions to make about
separating data and processing between the client workstations
and the database server. The database server encapsulates database
files and indexes, restricts access, enforces security, and provides
applications with a consistent interface to data via a data dictionary.
¨iGraphic images or files that can be imported to word processing and
desktop publishing documents are called electronic clip art.

Clip art for computers, just as in the printing and art industry,
is available in various graphics file formats and is typically
available as specialized libraries for different purposes such as
medical, business, holiday seasons, sports, and so on. As an
example, your company logo could be scanned with a graphics hand
scanner, saved as a clip art file, and later imported with your
desktop publishing program to a document.
There are 2 types of clip art files, object oriented and bit-mapped.
The object oriented uses draw-program-type line art format, and will
always print a sharp image at any size, at the highest resolution.
Bit-mapped or paint-type clip art can be manipulated by adding text,
changing its size, rotating it, or stretching it, but it becomes
jagged when enlarged.
pA computer's clock is an internal timing device, often referred
to as the system clock. The clock speed is determined by a quartz

Every computer system utilizes a quartz crystal to regulate the
system clock. When the machine is turned on, electric current
causes the precisely cut sliver of quartz crystal to deform or
vibrate, at a constant rate, millions of times per second. A
voltage pulse is emitted with each vibration which, along with
other signals, controls the pace of action and ensures that the
circuits do not get out of phase.

The system clock speed is measured in megahertz, MHz.
©A clone is a copy or a look-alike. Clones are not the result of
an original idea or a new design; they are copies.

In the world of microcomputers, the term clone most often refers to
a computer system that resembles one of IBM's personal computers.
Shortly after IBM introduced the PC, the XT, and the AT, clones
appeared on the market claiming to be IBM-compatible. Some clones
were more compatible than others.
ûEA cluster is a group of sectors on a hard disk or floppy disk
that forms the fundamental unit of storage allocated by the
operating system.

The number of sectors in a cluster is determined by the computer's
operating system, not its hardware.
–\Coaxial cable is a data transmission medium noted for its wide
bandwidth and for its low susceptibility to interference. Signals
are transmitted inside a fully enclosed environment, an outer
conductor or screen which surrounds an inner conductor. The
conductors are commonly separated by a solid insulating material.

Coaxial cable has a greater transmission capacity or bandwidth
than standard twisted pair telephone wires.

Coax cable is used in connecting workstations in a network of
microcomputers. For example, local area networks using ARCnet
technology are tied together with coaxial cable.

See the Table "Local Area Network Cabling"
ýHCOBOL is a high-level computer programming language. The name is
an acronym from COmmon Business Oriented Language.

Since typical business-oriented applications require more data
manipulation as input and output than extensive computation,
COBOL is the preferred programming approach in the business

COBOL was originally designed for mainframes but is now appearing
on microcomputers to allow personal computer users to take advantage
of the massive amount of COBOL software available.
ÕWCode page switching is a DOS feature, versions 3.3 and later, that
changes the characters displayed on the screen or printed on an
output device. It requires an EGA monitor or better and a graphics
printer compatible with the IBM models.

For example, DOS 3.3 provides several pairs of code pages for
displaying international characters.

³ Code Page ³ Language ³
³ 850 ³ Multilingual, for most European and North and South ³
³ ³ American countries. ³
³ 860 ³ Portuguese ³
³ 863 ³ Canadian French ³
³ 865 ³ Norwegian and Danish ³
N#A computer's operating system is initiated with a boot procedure,
a start-up from scratch.

The IBM-compatible personal computers can be either cold booted or
warm booted. A cold boot process begins with turning on the computer's
power. Typically, the cold boot process consists of basic hardware
checking followed by loading of the operating system from disk into

It is not always necessary to turn-off the power and then re-apply it
to start the boot procedure. The system can be warm booted by
depressing the following three keys at the same time: CTRL-ALT-DEL.
ÖNA COM port is a communications channel or pathway over which data
is transferred between remote computing devices.

IBM-compatible microcomputers operating under DOS can have as many
as four COM ports, COM1, COM2, COM3, and COM4. These COM ports are
actually serial ports most often used with a modem to establish a
communications channel over the telephone lines.

The COM ports are also used to send data to a serial printer or to
connect a serial mouse.
æComma-quote-delimited is an industry standard file format or record
layout for transferring data between software applications. It is
also called comma-delimited.

The information in each record of the file is standard ASCII text.
Each record contains a number of fields separated by commas and
the data in each field begins and ends with a quote character.

dBase, FoxBase, FoxPro, Clipper, and the other xBase products provide
the capability of importing and exporting data in this format. The
following sample records are comma-quote-delimited:

"Sarah Peudic","14 Hospice Way","San Jose","CA","96370"
"Zeek Branlon","4915 22nd Avenue North","St.Petersburg","FL","33710"
"Sapnim Mann","P.O. Box 23","Chicago","IL","60602"
øaA compiler is a program that translates a source program written
in a high-level language into its equivalent machine language.

The output from a compiler is called an object program. A
compiler can also produce a program listing and diagnostics that
may result from errors detected during the translation.

Most programming languages have a compiler, for example,
a FORTRAN compiler, or a COBOL compiler, TURBO-C compiler.

The compiler also checks a computer program for syntax errors.
û5A monitor that accepts a video signal similar to that received by
a standard television set is called a composite monitor. That is,
the signal provides luminance (brightness) data that monochrome
and color monitors use, but the signal also has a sideband that
carries the hue and saturation data that only a color monitor can

A monochrome composite monitor uses the signal to display shades
of grey as equivalents to the colors that would appear on a color
composite monitor that received the same signal.

Color Graphic Adapters (CGA) can provide output suitable for
composite monitors; however the clarity of such monitors is
inferior to that provided by TTL monitors.

Composite monitors are rarely used with IBM PCs and compatibles.
¼&A computer is an electronic device for performing high-speed
arithmetic and logical operations.

There are five key parts to a computer: the central processor,
the arithmetic logic unit, the memory, and the input and output
devices. Most of our conventional computers adhere to the design
concept referred to as the Von Neuman architecture.

The three general classifications of computers are the microcomputer,
the minicomputer, and the mainframe, whose differences depend on the
type of processor, size of memory, and the input/output devices

Because of the rapid advances in computer technology, the boundaries
between these classifications are not clearly defined.
GThere are many different computer languages for writing programs
just as there are different spoken languages.

The following examples of computer programming languages are defined
further in this PC-GLOSSARY:


@}A computer program is a series of statements instructing the computer
to perform a task or process data.

The program may be in a high-level source code form, which requires
intermediate processing before the computer can execute it, or it may
be in an object form which can be directly executed by the computer.
XiWhen two or more items, such as character strings or files, are
joined together end to end to form a larger unit, they are said
to have been concatenated.

Two data files can be concatenated by appending all the records
in one file to the end of the records in another file. The larger
file is then said to be a concatenated data set.
†Conditional branch

A program instruction in which a condition is tested to determine
whether a branch will occur is called a conditional branch.

Unconditional branch

A program instruction or statement that does not test a condition
before a branch occurs is called an unconditional branch.
Program execution then jumps to another location, no matter what
condition exists.
ú}The CONFIG.SYS file is an operating system file that DOS searches for
each time the microcomputer is booted. It is not required but provides
many advantages. DOS only looks for it in the root directory of the
boot device (either the A: floppy drive or the C: hard drive).

Since the DOS commands in the CONFIG.SYS are executed each time the
system is booted, the operating environment for each particular system
can be optimized to take advantage of the attached hardware.

The CONFIG.SYS file is an ASCII text file and can be changed with any
text editor program such as EDLIN. In order for the changes to take
affect, the system must be re-booted.

If you have never seen one, at the C:\ prompt, enter the following
n.The term contiguous designates adjacent storage locations in main
memory or non-fragmented file space on a disk.

Oftentimes, as a result of extensive editing of a disk file, the
file becomes fragmented on the disk, broken into parts which reside
in different locations with pointers tying the file together. The
file is then referred to as non-contiguous.
;+Special characters are sometimes embedded in a data item to
specify an operation to be performed.

For example, a line to be printed could contain a control character
indicating that the printer should advance two lines before printing
on the page.

Throughout this glossary some of the words that appear on the screen
are displayed in a highlighted fashion or in different colors. That
feature is made possible by placing a control character before and
after those words in the pre-compiled version of this glossary.

See the Table "ASCII Control Codes"
RlIf your IBM-compatible computer hasn't locked-up, and the keyboard
is active, the system can be warm booted by depressing the following
three keys simultaneously: Ctrl-Alt-Del

A computer's operating system is initiated with a boot procedure,
a start-up from scratch.

When your system is warm booted, the contents of memory are not
actually erased. The operating system is simply reloaded, and the
pointers to the beginning of available memory are reset. In fact,
a DOS program called DEBUG can be used to read from the part of
memory that was in use prior to the warm boot.
]The Intel 8086 and 8088 microprocessor chips can address only
up to 1024 kilobytes of Random Access Memory (RAM). The Intel
80286, 80386 and 80486 CPU chips can address more than 1024
kilobytes of memory.

Conventional memory refers to the memory space between zero and
1024 KB that is directly addressable by the 8086 and 8088 CPUs
or by the 80286, 80386 and 80486 CPUs operating in real mode.

DOS and its applications are designed to use only the lower 640K
of this conventional memory space. The remaining 384K is used
for video RAM, the machine's BIOS, and/or RAM for hardware cards.
GbConvergence is an attribute of a color monitor that describes its
ability to focus the three colored electron beams on a single point.

The three colors, red, green, and blue that make up each pixel are
shot from electron guns. The sharpness of the image on the screen
is determined by the dot pitch and the quality of the convergence.

Poor convergence causes the characters on the screen to appear
fuzzy and could cause headaches and eyestrain. Unfortunately, poor
convergence quality cannot be corrected without opening the monitor
and adjusting the electron guns.
œWSince it is illegal to make a copy of copyrighted software and pass
it along to another person, many software developers devise methods
to prevent or discourage this unauthorized duplication.

Although copy protection has been implemented using various
techniques, sometimes very sophisticated, there is often another
program, called a copy buster, to unlock or override the copy
protection scheme.

Since the copy protection schemes can often be broken and because
they cause the purchaser unnecessary inconveniences when moving the
programs to a new hard disk, by the late 1980's most copy protection
had been removed from personal computer software.
EA copyright is the legal, exclusive right to the publication,
production, or sale of the rights to a literary, dramatic, musical,
or artistic work, or to the use of a commercial print or label,
granted by law for a specified period of time to an author, artist,
composer, programmer, etc.

If the product is a computer program such as this PC-GLOSSARY, it
must include the statutory copyright notice like the one that
appears on the opening screen, on all source code listings, on the
diskette label, and on all documentation.

Since the United States maintains a free-enterprise system, any
work that is not properly protected by copyright, is considered
to be in the public domain where anyone is free to use it.
A copyright is registered by depositing a copy of the work with
the Copyright Office in Washington D.C.
‹@One of the earliest types of memory used in computers, core memory
was composed of storage units, called magnetic cores, made from a
ferro-magnetic material and magnetized in either of two directions
to store a bit.

Core memory, now obsolete and never used in microcomputers, was
non-volatile and had a destructive read property requiring that data
be restored after it had been read.
úECP/M is an acronym for Control Program/Microcomputer.

It is an operating system created by Gary Kildall, the founder of
Digital Research. It was created for the old 8-bit microcomputers
that used the 8080, 8085, and Z-80 microprocessors. It was the
dominant operating system, before DOS, for personal computers of
the non-Apple variety.

CP/M included the Console Command Processor (CCP) and BDOS, the
Basic Disk Operating System. It allowed users to install a variety
of video displays and disk systems and actually made them work well
together, a not-so-common situation in the 1970's.

Actually, Microsoft Corp. bought the rights to a CP/M clone which
had been developed by Seattle Computer Products and sold it to IBM
as PC-DOS in 1981.
vUEvery computer has a Central Processing Unit. The CPU is the
portion of a computer where instructions are fetched, decoded,
and executed. The overall activity of the computer is controlled
by the CPU.

It consists essentially of an arithmetic unit, a control unit,
and an internal memory.

A minimum requirement is three registers, a decode and control
section, an adder, and two memory buffers.

The control of other functions is exercised through the
interpretation and execution of instructions.

Today's CPUs for microcomputers are contained in chips small enough
to easily fit in the palm of your hand.
xUThe term 'carriage return' originally defined the typewriter key
that returns the carriage to the initial position on a line. The
operator would then advance the paper one line to begin typing on
the next line.

On the keyboards used with today's computers, the carriage return
is the character code that is often used as an end of line or end
of command delimiter. 'Carriage return' is actually an improper
term for the key labeled RETURN or ENTER on most modern keyboards.

On many computer systems, the carriage return or a carriage return
and linefeed pair (CR/LF) is used to end a line of text in a text
Ç[A computer system or program is said to crash when it has become
inoperable because of a malfunction in the equipment or the

One of the most common reasons for a system crash is a fluctuation
or loss of power supply. It is wise to postpone important computer
operations during a thunder storm. In most cases, when the system
crashes due to a power fluctuation, rebooting the system will
normally restore proper operations.

However, one of the most dreaded types of crashes is the head crash.
A head crash, usually caused by some sort of disk contamination,
occurs when the read/write heads collide with the disk surface,
resulting not only in lost data, but also damaged hardware.
^1CRC is an abbreviation for Cyclic Redundancy Check.

To determine whether an error has occurred during the reading,
writing, or transmission of data, a CRC is performed by
calculating the CRC character, and comparing its value to the
CRC character already present in that block of data. If they
are equal, the data is assumed to be correct.
¸NCRT is an abbreviation for Cathode Ray Tube.

A cathode ray tube is a display screen like that of a television
receiver used with computer systems for viewing data.

A CRT or monitor for use with microcomputers typically displays
20 to 24 lines of data with 80 to 132 characters per line.

Conventional CRT displays produce an image by directing an electron
beam on a phosphorescent coating on the glass face of the tube.
When struck by the electron beam, the phosphor glows, producing the
light that reaches our eyes. When the beam stops, the light quickly
fades. Different phosphor compositions control how long the glow
lasts, and with color CRTs, what colors are produced.
ßNCarrier-Sense Multiple Access/Collision Detection (CSMA/CD) is a
network access scheme. It is a method by which a network station
obtains use of the physical network channel to send a message
across the network.
It allows all network users equal access to the one set of cables
that interconnect the network. No central node controls access.
CSMA/CD is used predominantly with bus topologies, like Ethernet.
When it detects a clear channel (carrier sensing), a node transmits
its message marked with the address of the receiver. All idle
stations (those not transmitting) continuously monitor the channel
for messages. The receiver of a message returns an acknowledgment
of receipt. The sender, meanwhile, awaits the acknowledgment. If
not received after a specified amount of time, the sender assumes
that a collision has occurred and re-sends the message after a random
amount of time. Collisions occur when two or more stations attempt
to transmit simultaneously.
ãwCUA is an IBM standard user interface for displaying data on the
screen. It is part of the SAA specifications which include OS/2
Presentaion Manager and the character-based formats of the 3270

The purpose of the CUA standard is to provide a consistent screen
appearance across hardware platforms and between various software

CUA includes many of the graphical user interface (GUI) tools and
techniques found in X-windows and the MAC interface.
t8A cursor is the blinking or flashing indicator on a display
screen which identifies a location.

The cursor is often a short highlighted line that appears under
the space where one character is to be entered or replaced.

Modern keyboards are equipped with cursor control keys usually
labeled with directional arrows, for left-or-right and
up-or-down movement.
Cybernetics is the field of science involved in the comparative
study of organic and machine processes. It explores the
similarities and differences between machines and human beings.

Cybernetics often refers to robots which imitate human behavior.
rWith magnetic disks, a cylinder consists of a vertical column of
tracks on a disk platter or disk pack.

With floppy disks that have only one disk platter, a cylinder
consists of the top and bottom tracks with the same track number.

On disk packs that have multiple platters, a cylinder consists of
all the same numbered tracks on both sides of all platters.
ÕZA daisy chain is a specific way of connecting a series of devices
to a computer, or more precisely, a method of propagating signals
along a bus.

This method is a bus line that is interconnected with units in
such a manner that a signal passes from one unit to the next in
serial fashion.

This daisy chain method of connecting devices establishes a
built-in priority scheme whereby the unit closest to the CPU
has the first or highest interrupt priority.
ö[An impact printer that prints fully formed characters one at a
time by rotating a circular print element composed of a series of
individual spokes, each containing two characters that radiate
out from a center hub, is called a daisy wheel printer.

In use, the wheel spins rapidly until the desired character is in
position. Then the hammer strikes the type, forcing it against the
ribbon and paper causing the character to be printed.

Daisy wheel printers produce letter quality output.
®;DAT, a cassette tape for storing large amounts of data, had its
origin in the audio world.

DAT technology emerged in Europe and Japan in 1986 as a way to
produce high quality, distortion-free audio recordings. It works
by converting recorded audio signals into digital data which can
be read by a computer.

It provides the capability to store large amounts of information
to a cassette tape both for backup purposes and for on-line data
storage. One cassette containing digital tape less than four
millimeters wide can store 1.3 gigabytes of data. That is
approximately the same storage capacity of sixty-five 20MB fixed
disks, or more than 3600 standard floppies.
A database is a set of interrelated data records stored on a
direct access storage device in a data structure that is designed
to allow multiple applications to access the information. A
database should have minimal redundancy of data and allow for
growth and change.

A database is a highly structured file that attempts to provide
all the information allocated to a particular subject and to
allow programs to access only those items they need.

The information you are now reading has been previously stored
in a database.
cQA database server is a microcomputer dedicated to the task of
encapsulating database files and indexes, restricting access,
enforcing security, and providing applications with a consistent
interface to data via a data dictionary.

A database server is often connected to a local area network so
that its services are available to the workstations.
ÌMThere are many types of Data Bus connectors such as DB-9, DB-15,
DB-19, DB-25, DB-37, and the DB-50. These connectors are used for
a wide variety of serial and parallel data input and output by many

The number following the DB- refers to the maximum number of lines
or wires within the connector. Not all of the wires or lines,
especially on the large connectors, always have an assigned function.

The DB-9 connectors are commonly used for RS-232 communications.

The DB-25 connector is often found on the computer end of a parallel
printer cable for PCs and a Centronics 36-pin connector is on the

printer end of the same cable. But the DB-25 is also used for serial
çsA DBMS is simply a computer program for managing the data contained
in database files.

A well-designed database management system allows the end user to
do all of the following:

define the structure of the information to be maintained;
define a custom screen layout for data entry; enter data;
retrieve individual records; view, edit, delete, or print
individual records; rearrange records into different orders for
on-screen or printed lists; select various subsets of the data
for different purposes; perform calculations and store, view,
or print the results; print formatted reports that present the
information in the database in a form readily accessible to people
who know little about computers and databases.
àBDCA, an abbreviation for Document Content Architecture, is a text
file formatting guideline designed by IBM that enables the exchange
of text-only documents between computer systems.

DCA provides for two types of document formatting, RFTDCA and FFTDCA.

RFTDCA, Revisable Form Text DCA produces documents with flexible
formatting that can be changed by the receiver.

FFTDCA, Final Form Text DCA produces documents whose formatting can
not be changed by the receiver.
These two abbreviations are described in an EIA standard as two
separate hardware devices connected by an RS-232 serial cable.
The difference between the two is the wiring of pins two and three.

The DCE, Data Communications Equipment, devices typically transmit
on pin 3 and receive on pin 2.

Examples of DCE devices: external modems, printers, routers

DTE, Data Terminal Equipment, devices typically transmit on pin 2
and receive on pin 3.

Examples of DTE devices: personal computers, terminals
ØoDDE is a form of interprocess communication implemented in mutitasking
operating systems such as Microsoft Windows and OS/2. Information,
commands, and status information can be exchanged between two or more
programs if they support DDE and are executing simultaneously.

For example, a spreadsheet with a DDE link to a communications program
could keep its stock prices current with the trading information
received over the communications channel.

An exchange of data in DDE is called a conversation and an application
can participate simultaneously in multiple DDE conversations with any
number of other applications. A conversation is organized around three
conceptual descriptors: service, topic, and item.
î|With multitasking operating systems, when multiple tasks are running,
they often need access to the same peripheral devices such as disk
drives, memory, printers, and other pieces of hardware.

Since each task competes with others for the same resources, it's
likely that, at some point in time, one task will have the resources
needed by another. The operating system should manage the tasks so
that the resources are properly shared.

But it's possible for the operating system to allocate resources in
such a way that it becomes impossible for any task to proceed. This
position is known as a deadlock or deadly embrace.

A deadlock is similar to a stalemate and is guaranteed to bring the
operating system to a grinding halt.
î<When a value, parameter, attribute, or option is assigned by a
program or a system in the absence of one specified, it is called
the default.

Oftentimes, a computer program will contain pre-specified values
that are used unless it is given alternative values. These
pre-specified values are called the defaults.

Some programs allow the operator a choice of two or more options.
If a selection is not made by the operator, a selection is then
automatically assigned, by default.
•UA delimiter is a special character that designates the beginning
and/or the end of a field or string of characters.


In the following line, both the comma and the double-quote are used
as delimiters;

"Sarah Peudic","14 Hospice Way","San Jose","CA","96370"

In the next line, a comma is used as a data field delimiter;

813, 323, 0961, 283.40, 1128, 4915.22, 33710, 317.46
SYThe number of bits or characters that can be recorded in a given
length of recording surface is called the density, often
expressed in bits per inch.

Large computer systems and minicomputers use open reel magnetic
tapes with 7 or 9 tracks or recording channels and densities of
200, 556, 800, 1600, or 6250 bits per inch (BPI).
h\The Data Encryption Standard was designated in 1977 by the National
Institute of Standards and Technology as the official method of
protecting unclassified computer data both in agencies of the
federal government and commercially. The DES was originally
developed by IBM researchers.

The DES is a single-key system, in which data is both encrypted and
decrypted with the same key. The key is a sequence of eight numbers
each between zero and 127. Under control of the key, the letters and
numbers of each block are scrambled no fewer than 16 times.

The DES then links the enciphered blocks together in such a way that
the encryption of each block, beginning with the second one, depends
on the results of encoding the one that precedes it. Consequently,
the final encrypted block is changed if a single character is altered
anywhere in the message.
vHA desktop computer is a type of microcomputer small enough to fit
easily on top of a desk. It contains the microprocessor, the input
and output devices, and a file storage device all in one unit. The
keyboard is a detachable type and the video display is a separate

Desktop computers are AC powered rather than battery operated like
most laptop computers.
3]A device driver is a system file or software component that contains
the instructions necessary to control the operation of a peripheral
device. It contains the detailed information about the device it

The standard device drivers are part of the operating system, and
additional drivers are added as new peripheral devices are installed.

For example, if a mouse or trackball is added to your personal
computer, the appropriate device driver needs to be installed so that
the operating system can communicate properly with it.

Device drivers associated with application packages such as desktop
publishing programs typically only perform the data translation.
These higher level drivers rely on the standard drivers to actually
send the data to the device. (printer, plotter, CD-ROM, etc.)
;A device monitor is an operating system program or class of programs
that track or monitor the data stream being processed by a character
device driver.

OS/2 provides such a class of programs that simplify, standardize,
and enhance the process of managing TSR programs.

The device monitors wait for and react to the event that triggers
a memory resident program to the foreground.

Since DOS was not designed to support TSR programs, a form of pseudo-
multitasking, many unpleasant side effects can occur when TSRs or
pop-up programs are used together.
ì@The performance of a computer system is often evaluated by measuring
its operational speed in a variety of different tasks.

The Dhrystone benchmark program is used as a standard figure of
merit indicating aspects of a computer system's performance in areas
other than its floating-point performance, for instance, integer
processes per second, enumeration, record and pointer manipulation.

Since the program does not use any floating-point operations,
performs no I/O, and makes no operating system calls, it is most
applicable to measuring the performance of systems programming

The program was developed in 1984 and was originally written in Ada,
although the C and Pascal versions became more popular by 1989.
6AThere are two main ways of doing things electronically, analog or

The digital method is to consider a circuit either on or off,
a signal as either present or absent, with no levels in between.

Electronic circuits using the digital mode are simple to design
and non-critical in operation. The all-or-nothing nature of
digital circuits make them immune to drift and distortion, and
their simplicity makes them easy to manufacture in large quantity.

Digitizing is defined as transforming a signal or piece of
information into digital form.
€XA digitizing tablet is an input device for obtaining accurate
graphics input. It is connected to the microcomputer with a cable
and includes some type of pointing device called a transducer.

The tablet has a flat surface with a defined space, or active
drawing area, where the operator can place a map, a drawing, or a
menu overlay. A pointing device is then used to pinpoint areas
within the work space, and the tablet sends coordinate data to the
CAD application program. While a mouse reports a relative position
based on its last known position, a digitizer returns an absolute
location regardless of the last known position of the transducer.

Compared to a mouse, a digitizing tablet is more precise and can
take samples faster. Also, because the stylus and fixed surface
provide for a more natural drawing motion, artists and designers
prefer digitizing tablets.
(DIN is an abbreviation for Deutsch Industrie Norm.

The DIN connector is a multiple pin connector conforming to the
specification of the German national standards organization.

On most IBM-compatible microcomputers, 5-pin DIN connectors are
used to connect the keyboard to the motherboard of the system

An 8-pin DIN connector is used as the serial port connector on the
Macintosh line of computers.

The PS/2 line of IBM computers use a 6-pin DW connector to connect
the keyboard and the pointing device.
¦Dingbats are special graphical characters, not letters or
numbers, which represent a wide variety of ideas. They are
also used for decorative purposes in a document.

The ASCII characters 1 and 2 (the smiling faces) are dingbats.

The new Unicode has a number of codes reserved especially for

Dingbat font cartridges for desktop publishing are available.
The most popular is the Zapf Dingbats font.
»9DIP is an acronym for Dual In-Line Package.

Printed circuit boards and peripheral devices are often equipped
with a bank of DIP switches. There are two styles; slide
switches and rocker switches. In both cases, the switch positions
can be set on or off with a ball point pen or some other pointed

These hardware switches allow for a variety of operating conditions
to be set before the board or device is put into use.
²?A directory is an area on a disk for storing files. Directories
consist of files and/or subdirectories.

A directory listing will show the names of files and subdirectories
subordinate to that directory along with file sizes, creation dates
and times.

Each formatted disk contains a main directory also called the root
directory. With DOS, the most common hard disk root directory is
referred to as "C:\" or just "C:".
«Directory hashing is an operating system technique for reducing
the time spent in searching for file locations.

Information about the location of disk files and all their parts
is stored on the disk itself. The directory hashing process not
only reads that information into memory but it also indexes it
for faster retrieval. With directory hashing, the response time
for disk I/O can be reduced by as much as 30%.
bFiles stored on a disk are arranged in tree-structured directories.
The main directory on a disk is called the root directory. It can
have files and/or other directories subordinate to it.

³ The root directory has either files or subdirectories under it. ³
³ Subdirectory ³ ³ One file ³ ³ One file ³ ³ Subdirectory ³
³ One or more files or subdirectories.... ³ ³ Subdirectory ³
³ One or more files or subdirectories.... ³
<A disk is a type of magnetic storage media. The storage capacity
varies greatly from single-sided floppy diskettes to high
capacity fixed disks and disk packs.

A disk is the most common type of direct access storage device.

The terms disc and disk are used interchangeably.
TA disk cache is a software technique of speeding data access times.

Copies of recently accessed disk sectors are stored in memory to a
reserved area called cache RAM.

When the executing program or the operating system requests to read
a sector from the disk, the disk caching software checks to see if
the sector is stored in cache RAM. If it is, the sector is retrieved
from RAM and returned; no disk access is required. If the desired
sector is not in cache RAM, the software reads the requested sector
from the disk, stores it in cache RAM, and returns it to the program.

When the info is found in the cache, it's a hit. When the info must
be retrieved from the disk, it's a miss.

Some disk caching programs also check for sector writes.
ýSDisk mirroring is the process of performing all disk writes to two
separate hard disks. Both disks contain exactly the same information.
The second disk is a mirror image of the first.

In case one of the disks fails, this fault tolerant capability allows
the system to continue to function without pause from the remaining
single disk. Disk mirroring technology has been active on mainframe
and minicomputers for many years and has just recently begun to appear
in the world of desktop microcomputers.

Disk duplexing includes the process of disk mirroring but includes
redundant controller boards and cabling. It is therefore more
complex and provides a greater degree of fault tolerance. Disk
duplexing is performed on two separate channels.
@GThe diskless workstation gets its name from the fact that it has no
local floppy or hard drive available. It consists of just a monitor
and a keyboard. A local printer is optional.

Also sometimes referred to as diskless LANstation, this type of
workstation can only be used as a node on a network. It gains
access to the network through software on a ROM chip which can be
located on the network interface card or built right into the

The biggest disadvantage to using a diskless workstation is that it
become useless if the network is down.

Some companies utilize diskless workstations as a security measure
by preventing users from copying data. However, if the diskless
workstation contains an expansion slot, a hardcard could be easily
connected for transferring data from the file server.
ñ/DIX is an abbreviation for Dec-Intel-Xerox.

A DIX connector is a 15 pin connector on a Network Interface Card.

As an example of its use, the Ethernet Local Area Network interface
cards (NIC) have two cable connectors, a DIX connector and a BNC
connector. One or the other can be used. If the BNC connector is
selected, the board will use its own built-in circuitry. If the
DIX connector is selected, the board will bypass the internal
transceiver and use an external transceiver.
YDow Jones News/Retrieval is an on-line service with a text-based
interface founded in 1974 by the Dow Jones Co., publishers of the
Wall Street Journal. It is the oldest and most respected provider
of online financial information.

Services include: financial news, stock market quotes, statistical
data for over 1500 mutual funds, pricing, dividend, and financial
data for up to 15 years on 120,000 U.S. and Canadian stocks and
bonds, on-line trading, and investment research.

For current fees and more information:

Dow Jones Information Services 800-522-3567, Ext. 294
in Princeton, NJ dial 609-520-8349, Ext. 294
JSDLLs are libraries of object files or executable code modules
available to programmers writing code for the Microsoft Windows
operating environment.

Functions and procedures written in languages like Pascal and C can
be compiled and the object file stored in a DLL. These modules can
be loaded at run time, and then unloaded when the code is no longer

The use of DLLs allows for a high degree of customization. If a
particular development language doesn't support a required function,
it could be written in another language and made available through
the DLL.
êMAfter a sector of data has been read from a disk drive into the
disk controller's onboard buffer it must be moved into the
computer. This is done with a process known as DMA or

(Direct Memory Access).

The transfer of data takes place directly along an input/output
channel at high speed between memory and the device. The CPU
only initiates the transfer on a DMA request and therefore is
not involved.

The time required to transfer the disk sector determines how soon
the controller will be ready to read the next sector. For this
reason add-in Accelerator "Turbo" Cards do not generally change
a machine's optimum interleave since the main system clock speed,
which continues to control DMA memory accesses, is not changed.
ÀEDocumentation is a collection of written descriptions and procedures
that provide information and guidance about the proper operation and
maintenance of a computer program or peripheral device.

For computer programs, on-line documentation is the preferred method
of access to its operation and/or description. Sometimes this
information is even available during the operation of the program by
entering a special keystroke combination.
”HDOS is an acronym for Disk Operating System.

It is an operating system for microcomputers developed by Microsoft
Corp. for IBM's 16-bit machine, the IBM PC and compatibles.

DOS is actually a clone or a re-write of CP/M, an operating system
for earlier 8-bit computers. DOS was written for the 16-bit 8086
and 8088 microprocessors.

There are almost as many varieties and versions of DOS, as there are
different types of IBM-compatible microcomputers.

IBM's version of DOS, maintained by Microsoft, is called PC-DOS.

MS-DOS, also maintained by Microsoft, is available to clone makers
using Intel's 8086 family of microprocessor chips.
,An impact printer that prints characters composed of dots is
called a dot matrix printer. Characters are printed one at a
time by pressing the ends of selected wires against an inked
ribbon and paper. The wires are arranged in various sized
†UThe sharpness of the images that appear on your computer monitor
is defined by the dot pitch. Dot pitch measures the width of the
dots that make up a pixel. The smaller the dot pitch, the sharper
the image.

Color monitors use three dots in red, green, and blue (RGB) to
focus on a single point or dot to make up a pixel. On monochrome
monitors, each dot is a pixel. The accepted standard dot pitch is
31/100 of a millimeter (.31mm).

The dot box is defined by having so many pixels wide by so many
pixels high.

Dot box examples for popular display adapters:

CGA - 8x8, MDA - 9x13, EGA - 8x14, VGA - 9x16
Ü0When two computer words are used to store an item of data to
maintain a higher level of precision, the task is said to be
executed in double precision.

Often an entire program is coded to run in double precision.
"EBoth download and upload are relative terms referring to the
process of transferring data and/or program files from one
computer to another, or from a computer to a peripheral device.

There are many modern computer systems that maintain large
libraries of software programs. These programs can be downloaded
to other computers over the telephone lines, using a modem and a
communication software package which handles the protocol.

On a Local Area Networks, data files and programs are downloaded
and uploaded to the file server.
q DRAM is an acronym for Dynamic Random Access Memory. It is a memory
chip in which data is stored capacitively and which must be energized
or recharged hundreds of times a second or the data will be lost.

While DRAM is being refreshed, it cannot be read by the processor. If
the processor attempts to read the DRAM while it is being refreshed,
one or more wait states occur.

DRAMs offer high bit densities, low cost, input/output compatibility
with TTL levels, and speed compatibility with most microprocessors.

The operational speed of DRAM chips is measured in nanoseconds, such
as 150, 120, 100, and 80ns.
ÆTDesktop Publishing is the art of using a personal computer to merge
text and graphics files to produce high-quality output usually on a
laser printer. It requires a desktop publishing software package,
a powerful personal computer with a hard disk, and a graphics-based
monitor that can display one or two full pages at a time.

The text files are often created using word processors or text
editors while the graphics files are created with CAD software or
paint and draw programs. Scanners can also be used to capture
graphics files from pictures, drawings, and photographs. Both text
and graphics files can then be copied into the desktop publishing
system for merging, editing, and output.
äLTerminals, or workstations with a video screen and keyboard, were
used for many years before microcomputers to provide for the input
and output of data to and from mainframes and minicomputers.

The term "dumb terminal" came into use about the same time that
microcomputers began to proliferate. As microcomputers became more
and more powerful, terminals continued to provide the same services,
they could not perform any stand-alone processing. Hence, they are
referred to as "dumb terminals" to distinguish them from the more
capable and smarter microcomputers that looked very similar.

Microcomputers now can execute programs that emulate most kinds of
terminals such that the host computer cannot tell the difference.
vA dump is a copy of the contents of storage locations in main
memory at a specified point in time. A dump can be recorded on
paper, to tape, or to a file to be used for debugging purposes.

This example shows a dump of memory starting at address 0000:0000

0000:0000 E8 4E 37 01 33 FF 0F E5 00 F0 33 FF 00 F0 N7 3 3
0000:0010 33 FF 00 F0 54 FF 33 FF 00 F0 33 FF 00 F0 3 T 3 3
0000:0020 95 E6 00 F0 26 01 33 FF 00 F0 33 FF 00 F0 & y53 3
0000:0030 33 FF 00 F0 BE 01 57 EF 00 F0 33 FF 00 F0 3 W 3
0000:0040 65 F0 00 F0 4D F8 41 F8 00 F0 69 02 79 35 e M A i
0000:0050 39 E7 00 F0 59 F8 8A 01 79 35 0B F9 00 F0 9 Y y5
0000:0060 00 00 00 F6 4E 01 D3 05 84 38 F2 00 EF 07 N 8
0000:0070 FE 01 79 35 A4 F0 22 05 00 00 33 FF 00 F0 y5 " 3
0000:0080 C3 12 37 01 59 01 2F 01 D7 22 3C 01 D7 22 7 Y #/ "<"
úThe Digital Video Interactive technology combines motion video,
still pictures, multitrack audio, and computer graphics, into a
single integrated environment controlled by a personal computer.

Implemented by DVI boards and chip sets, the goal of DVI is to
eliminate the expense, complexity, and awkwardness of a part-analog
and part-digital system by storing and processing everything as
digital data.

DVI was conceived by Larry Ryan of the David Sarnoff Research
Center (RCA Laboratories) in 1983. The DVI project and technology
was acquired by General Electric when RCA dropped out of the
videodisc and home computer business. Today, Intel Corporation
owns the DVI technology and will soon be mass producing DVI boards
and DVI chip sets.
….Designed by August Dvorak, patented in 1936, approved by ANSI in
1982, the Dvorak keyboard provides increased speed and comfort and
reduces the rate of errors by placing the most frequently used
letters in the center for use by the strongest fingers. In this
fashion, finger motions and awkward strokes are reduced by over
90 percent in comparison with the familiar QWERTY Keyboard.

The Dvorak keyboard has the five vowel keys, AOEUI, together under
the left hand in the center row, and the five most frequently used
consonants, DHTNS, under the fingers of the right hand.

Some businesses are requiring their keyboard personnel to use this
system. Also, several computer companies are now manufacturing
keyboards with a switch that will change from one keyboard design
to the other. There are also TSRs with keyboard macros to convert
your present keyboard to the Dvorak style.
¹Extended Binary Coded Decimal Interchange Code is a standard
8-bit code for the representation of characters. It allows 256
possible character combinations and stores one alphanumeric character
or two decimal digits within a single byte.

EBCDIC is the standard code on IBM mini-computers and mainframes,
but not on the IBM microcomputers, where ASCII is used.

EBCDIC, pronounced "ebb-sa-dick", is an alternative to ASCII Code.
FqWhen data is being transmitted, the receiving device often
re-transmits the information back so that the originating device
can be sure it was received correctly.

On a telephone line, there is a device called an echo suppressor
that blocks the listening side while one person is talking in order
to eliminate echoes.
+WAn edge connector provides a means of interconnecting two printed
circuit boards. The connector consists of a row of etched lines
on one side or edge of the board that is to be plugged into another

The motherboard or system board in most computers has a number of
expansion slots for add-on boards. The add-on boards with their
edge connectors plug into the motherboard.

All of the following examples of add-on printed circuit boards
or cards utilize edge connectors:

Internal modems, video cards, hard disk controller cards
#One of the major problems associated with electronic mail is the
linking of different systems together to speed the movement of
information that gets put into forms, like invoices, order forms,
bills of lading, etc. As more and more organizations implement and
link networks of computers, the need for exchanging information with
other organizations will continue to increase and updated universal
addressing schemes will be required.

The Electronic Data Interchange System addresses this problem and
allows for the exchange of business information between companies.
EDI keeps track of inventory and allows customers to re-order from
their suppliers electronically, from computer to computer.

In the United States, EDI is defined by the ANSI X.12 standard.
zAs the term suggests, EFT refers to financial transactions that
originate at a terminal or microcomputer and cause the exchange of
money from one bank account to another.

This type of convenient banking is expected to become more and more
popular as the number of home computers grows.

In order to take advantage of this service from home, your computer
must be equipped with a modem for dialing-out.

One of the most successful EFT programs for microcomputers is
CheckFree from CheckFree Technologies, Inc. in Columbus, Ohio.
~An Enhanced Graphics Adapter is an IBM video display adapter
that can be used with color and enhanced color displays.

It also provides a monochrome graphics mode.

In color it can produce characters in a dot box of 8 by 14
pixels when used with an enhanced color display.

The EGA operates at a horizontal scan rate of 21.85 MHz, and
can display 16 colors from a palette of 64 at a resolution of
640 by 350 pixels.

To be fully EGA compatible, a video display monitor must have
a bandwidth of at least 16 MHz.
°^The Industry Standard Architecture (ISA) for IBM-compatible
microcomputers defines the use of the data bus and the 8-bit and
16-bit expansion slots on the PC-XT and PC-AT models.

EISA is the Extended ISA.

The EISA consortium led by Compaq Corporation and joined by almost
all microcomputer manufacturers except IBM, was formed in 1988 to
offer an alternative to IBM's Micro Channel Architecture (MCA).

The issue concerns non-IBM system and board manufacturers because
the MCA does not provide upward compatibility with existing machines.
With an EISA bus, 8- or 16-bit add-in boards based on the Industry
Standard Architecture (ISA) can be fitted to the new machines.
HrA typical ElectroLuminescent display consists of a thin film of
EL material (phosphor) sandwiched between thin films of insulating
dielectric material. The front material is transparent, while the
rear material is reflective. The zinc-sulfide-with-manganese
phosphor emits a bright yellow light when subjected to approximately
200 VAC. The voltage is applied via a grid of electrodes, each
pixel of which can be individually switched on. Other phosphors can
be used for different colors.

EL displays offer better contrast and broader viewing angles than
gas-plasma and LCD displays. They use more power than LCDs but
less than gas-plasma and considerably less than CRTs. They are
the most rugged type of display and are more reliable than CRTs.

EL displays are still offered primarily in monochrome configurations.
RDThe following acronyms are frequently used to save time and bytes
during on-line conferencing in electronic forums and in E-mail.

BTW - By The Way
FWIW - For What It's Worth
g,d&r - grinning, ducking, and running
IMCO - In My Considered Opinion
IMHO - In My Humble Opinion
OTOH - On The Other Hand
OIC - Oh, I See!
PITA - Pain In The Arse
PPN - Programmer Project Number or a CompuServe User's ID#.
RSN - Real Soon Now
ROF,L - Rolling On Floor, Laughing
RTFM - Read The Friggin' Manual
WYSIWYG - What You See Is What You Get
ÇElectronic mail systems allow computer users to exchange
information quickly and easily on a network of computers.
The most sophisticated electronic mail systems provide a wide
array of transfer functions for the exchange of documents,
binary files, graphics, and even such exotic data as voice
messages and video images.

There are three major segments of the E-mail industry:

LAN-based, PC users on a single or multiple local area network.

Host E-mail, runs on mainframes and minicomputers as an important
component of office automation.

Public E-mail is provided by communications-oriented companies and
it is accessible with a modem over telephone lines.
=On a Local Area Network (LAN), read and write requests for data are
by far the most common requests made by workstations to the file
server. Program files and data files both reside on the network
disk and must be disbursed on demand to the workstations. Overall
file server performance can be greatly affected by how well the
server responds to these requests for data.

"Elevator seeking" is a separate disk read process that is
responsible for reading data from the file server's hard disks and
placing them into cache buffers. Incoming requests are sorted into
an order of priority based on the disk drive's current read/write
head position. This technique optimizes disk head movement and
results in significantly higher disk throughput under loaded
– Embedded commands are codes that are placed within a file to
control a hardware device such as a printer.

In word processing, embedded commands are used to send instructions
to a printer for changing the print characteristics, such as the
font. There is no standard for these commands. They vary from one
application to the next.

An embedded system is a specialized computer system designed to
control the unit in which it is housed. It is custom programmed for
a specific task and usually consists of both system and application
software functions.

Embedded systems are contained in guided missile systems, rockets,
and space vehicles.
ÌAn emoticon is a figure created with the symbols and punctuation
characters of a computer keyboard and are used to convey the spirit
in which a line of text was typed. 🙂

An emoticon is an acronym created from the terms "emotion and icon".
Tilt your head slightly to the left to read the following emoticons.

🙂 or :-> Grin, happy face 🙁 Unhappy
😎 Smile with glasses
:-O Shout :*) Clowning around
<:-) For dumb questions
=|:-)= Uncle Sam @>--->---- A rose.

Other emoticons often appear in electronic forums and E-mail. If
you encounter one not shown here, and need an explanation, call us.
•?The Expanded Memory Specification provides a way for microcomputers
running under DOS to access additional memory. It was developed by
Lotus Corp., Intel Corp., and Microsoft Corp. and is also called the
LIM Spec.
Systems can use memory expansion boards and application software
that follow this specification to enable programs to handle memory
or RAM beyond the 640K that MS-DOS handles conventionally.

The Enhanced EMS (EEMS) was developed by AST Research, Ashton-Tate,
and Quadram Corp. It is an upward compatible enhancement to the
LIM Spec or EMS 3.2, whereby EEMS boards and compatible programs can
devote a larger amount of conventional memory to the window used to
access expanded memory, resulting in more potential expanded memory.
EMS Version 4.0 type memory can map multiple pages of varying size
into conventional memory enhancing both data access and program
execution capabilities.
Ó1A device which has been given a signal that permits it to
function is said to be enabled.

The opposite of enabled is disabled.

Software commands can be issued to enable or disable peripheral
.eIn object-oriented programming, encapsulation is the process of
gathering and grouping of data and the code that manipulates it into
a single object. If a change is made to an object class, all objects
of that class are updated. This is one of the major benefits of
object-oriented programming.
6YThe ultimate user of the output produced by a program or a system
is called the end user.

You, the consumer, are the end user of the software and hardware
that you purchase. You are the end user of this PC-GLOSSARY.

If you have any suggestions for improvements, please contact
Disston Ridge, Inc.
I0The best quality graphics are vector graphics where the image is
made up of lines, curves, and filled regions rather than a series
of data points as in bit-mapped graphics.

EPS stands for Encapsulated PostScript, which refers to a
condensed graphics file containing actual PostScript language in
a special format.

EPS files can become quite large, and some contain a bit-mapped
image of the graphic so that if the output is sent to a non-
PostScript printer, the bit-mapped image is used, but to get the
best results, EPS files should be output on a PostScript device.
ÑQErgonomics is the study of human posture and proportion in order to
design furniture and equipment that can be used comfortably and without
strain. It is frequently called human engineering, and emphasizes the
safety, comfort, and ease of use of human operated machines, such
as computer workstations.

Tangible results of ergonomics are the addition of numerical keypads
on standard keyboards, and tilt/swivel bases for non-glare video
display screens.
œrIn conjunction with the ANSI.SYS Device Driver, a DOS system
software program, escape sequences can be used to add a great
deal of useful or merely entertaining information to the display
screen. An escape sequence usually has the following four elements:

The Escape character, a left bracket, a numeric parameter, and
a terminating code indicating the function of the sequence.

For example, a sequence to set the cursor at the upper left
corner of the screen takes the form


where 1;1 is the horizontal and vertical position of the cursor,
and f is the code telling ANSI.SYS that this is the horizontal
and vertical position sequence.
èWEnhanced Small Disk Interface is a hardware standard developed
by a consortium of 22 disk drive manufacturers. The ESDI provides
for a maximum data transfer rate to and from a hard disk of 10
megabits per second and can manage disk drives with up to one
gigabyte of storage.

An ESDI hard disk controller card (ie. the circuitry that controls
a hard disk's operations) can only be used with a hard disk that
has an ESDI interface.

See the Table "Disk Data Transfer Rates"
¼=Ethernet is a type of network topology which breaks the data into
sealed and addressed packets, delivering them across the cable to
the recipient workstation, and confirming delivery. A network
supporting Ethernet transfers data packets using coaxial, twisted
pair, or fiber optic cabling. Two kinds of coaxial cable are used,
thick and thin. Most adapters these days include an on-board
transceiver for thin Ethernet.

Developed in the late 1970's by Bob Metcalf at Xerox Corporation,
and endorsed by the IEEE as 802.3, Ethernet is one of the oldest
LAN communications protocol in the personal computing industry.
It is also one of the fastest, running at 10 megabits per second.
However if two workstations attempt to transmit or receive data at
the same time, a collision occurs and the data must be transmitted
again. Data transmission is supervised by a protocol called CSMA/CD,
Carrier Sense Multiple Access/Collision Detection.
cThe process of carrying out the operations specified in the
instructions of a program is referred to as program execution.

In the DOS environment computer program files, sometimes called
executable code, are given filename extensions of .EXE or .COM.

Execution time can refer to one of three periods of time:

û The time required to fetch, decode, and execute an instruction.

û The phase during which a program is being executed.

û The time it takes for a program to run from start to finish.
ÖAWith microcomputers operating under DOS, the amount of memory that
can be utilized for working programs and data, without the use of
extended or expanded memory, is 640 kilobytes.

Expanded memory refers to memory that acts as a pool which can be
mapped into one or more conventional memory areas. Unlike extended
memory, expanded memory is available for all processor types. It
requires a special device driver and conforms to a standard
developed by the Lotus, Intel, and Microsoft Corporations. The
standard is called the LIM Spec or EMS, or EEMS, or EMS 4.0.

Expanded memory works with a bank-switched memory board, the EMM,
Expanded Memory Manager, and an application program that knows how
to use it.
™<On the main circuit board or motherboard of a computer, there are
expansion slots or receptacles into which other printed circuit
boards can be plugged.

Since they are connected to the computer's address bus, the number
and type of expansion slots determines how a system can be enhanced
with additional peripheral devices or memory boards.

On the IBM-compatible microcomputers, there are three different
types of expansion slots. The 8-bit slots are found on all the XT
models. The AT-style computers utilize both the 8-bit and 16-bit
slots. The new 80386 machines can utilize the 32-bit slots as well
as the 8-bit and 16-bit expansion slots.
}/With microcomputers operating under DOS, the amount of memory that
can be utilized for working programs and data, without the use of
extended or expanded memory, is 640 kilobytes.

Extended memory is available only with the 80286, 80386 or the
80486 CPUs and refers to memory above 1 megabyte. It is directly
addressable in protected mode.

Under DOS, RAM disks or virtual disks can be created in extended
memory but not used for processing. Extended memory is best
utilized by operating systems running in protected mode, such as
UNIX or OS/2, or by operating environments running with DOS such
as Windows or DESQview.
?Introduced in 1988 by Western Digital and Columbia Data Products,
FASST is a software specification that allows developers to easily
interface their hardware devices to a SCSI interface and to
operate those peripherals under a number of operating systems.

FASST implements a SDLP interface and its software handles the
handshaking between the peripheral and the attached SCSI adapter.
Thus a peripheral can be developed that makes system calls to the
FASST software, which in turn handles interfacing to the board.

This approach solves two problems:

It allows a user to upgrade from an 8-bit to a 16-bit SCSI adapter
without worrying about incompatibilities. It also allows devices
attached to the SCSI adapter to be run under DOS, Unix, Windows,
NetWare, and OS/2.
*The File Allocation Table is a system area on a disk that keeps track
of disk clusters allocated to all the files on a DOS partitioned

The FAT also keeps track of available disk space. In the case of a
hard disk, the size of the FAT limits the amount of storage capacity
that can be handled under DOS.

With DOS 3.3 and earlier versions, hard disks are limited to 32
megabytes of storage.

Hard drives with more than 32 megabytes of available storage can be
partitioned into small segments. These higher-capacity hard disks
come with special drivers that modify the FAT thereby allowing DOS
to use the additional storage space.
NaA fault tolerant computer system is designed to provide continuous
operation in the event of a failure. Such a system consists of
redundant components and processes that are designed to immediately
replace any failed component.

Totally fault tolerant systems not only require backup power sources
but also imply a duplication of systems in another distant location
in the event of a natural disaster or act of vandalism.

Fault tolerant computer systems are widely used in the finance
industry for operations such as stock market transactions and on-line
banking functions.
¾5A FAX board is an add-in printed circuit board for a personal
computer that allows the system to send and receive text and
graphics data over the telephone lines. A FAX board is actually
a facsimile machine in a personal computer.

FAX boards communicate via the CCITT Group 3 standard using a modem
at 9600 bits per second, half-duplex, and include a data compression
scheme to speed data transfer times.

Transmission time varies depending on the compressibility of a given
page, but it typically ranges from 30 to 60 seconds. On poor
quality telephone lines, the FAX modem will drop back to 7200 bps,
then 4800 bps, and then even 2400 bps to allow the data to transfer
error free.
„cFacsimile communication has been around much longer than electronic
computers. In fact, its origin can be traced to 1842 when a Scots
clockmaker named Alexander Bain made the first machine capable of
transmitting crude images for short distances over telephone wires.

The advancement of digital technology has replaced the older, slower
analog fax machines with faster, cheaper, easier-to-use facsimile
machines that can transmit pictures of original documents. Almost
anything on paper can be sent from any telephone to another telephone
in about one minute.

Facsimile transmission can be done from your personal computer and
is essentially a kind of electronic mail that can transmit to and
from any place in the world at any time of the day or night, on
weekends or holidays. The only requirement is two facsimile
machines or boards connected by an ordinary telephone line.
_*Beginning in 1978, in answer to some specific complaints of
interference to radio communication, the Federal Communications
Commission began a painful rulemaking procedure which resulted in
new regulations regarding Computing Devices.
The legal responsibility for compliance with the rules rests on the
shoulders of the company which integrates the various parts of the
computer system which is sold to the end user.

For regulatory purposes, the FCC has defined two categories of
computing devices, Class A and the tougher Class B.
Class A Computing Devices are those marketed for use in a business,
commercial, or industrial environment.
Class B Computing Devices are those marketed for use in a residential
area; Personal Computers, electronic games, electronic organs, etc.

REF: FCC Regulations, CFR 47 Part 15 Subpart J, Computing Devices
ª)The American National Standards Institute (ANSI) has defined a new
standard, FDDI, for local area networks using fiber optic cable.

FDDI is very close to the IEEE 802.5 standard and uses an
architecture similar to that of IBM's Token Ring. FDDI can support
very large LAN's, up to 500 nodes within a 100 kilometer (62 mile)
circumference, and data transfer rates up to 100 megabits/second.

A key to FDDI's high performance is its use of 1300 nanosecond
wavelengths to optimize the fiber's bandwidth. It also needs no
special repeaters, amplifiers or other signal-conditioning
equipment, since it employs commonly available fibers and electro-
optical components.
‘One femtosecond is one quadrillionth of a second, or a millionth
of a billionth.

There are about as many femtoseconds in one second as there are
seconds in thirty million years.

There are 1,000,000,000,000,000 femtoseconds in one second.

The combining form 'femto' is derived from the Old Danish word
femien for fifteen.

Femto is used to designate 10 to the minus fifteenth power.
7*Fiber optics is the technology of transmitting data over communication
lines made from flexible strands of glass or plastic through which
laser beams or light from LEDs are passed to transfer data.

The strands are formed into cables and can carry many more times the
amount of data than traditional copper wire.

Fiber optic cable, although it does not improve transmission speed,
can send data over great distances.

Radio transmitters, arc welders, and noisy fluorescent lights have
no effect on the light pulses traveling inside fiber optic cable.
ÊSAn acronym for First In - First Out, FIFO is a programming method
of storing and retrieving items from a list, table, or stack, such
that the first element stored is the first one retrieved.

An acronym for Last In - First Out, LIFO is a programming method
of storing and retrieving items such that the last item in is the
first one retrieved.

Push-down list is a list written from the bottom up, with each new
entry placed on the top of the list. The item to be processed first
is the one on the top of the list.

A push-down stack is a set of memory locations or registers in a
computer that are accessed via the LIFO method.

Most microprocessor program stacks operate on the LIFO method.
The next generation of computers, predicted to be in use before
the year 2000, will be referred to as fifth generation computers.
Their increased computational power is expected to result from
parallel processing or the ability to process several programs at
the same time.

They are expected to be true knowledge systems, able to combine one
set of facts with other sets to produce sophisticated new solutions.
No other computer has yet accomplished that task.

To play the central role in society that present day scientists
envision, these machines will need to be easier to use and will
understand spoken, written, and graphic input.
^1A file is simply a recording of information. Computer data and
programs are stored on floppy diskettes, hard disks, or tapes
in a manner very similar to the way your voice is recorded with a
tape recorder, magnetically.

A complete collection of related data is a file, an example would
be a mailing list file.

One complete unit of the information in a file, is called a record.
In the mailing list file example, all the information connected
with one address would be a record. Within a record, are fields.
The zip code would be one field, in an address record, in the
mailing list file.
êThe term "compression" means to reduce in size. Computer file
compression is achieved with an archiving program. Files are
quickly reduced in size. This process creates archive files which
have three distinct benefits:

û They use less disk space than normal files and increase the life
and storage capability of your expensive hard disk.

û Many individual files can be stuffed into a single archive file.
This allows for file group identification and organization.

û Archived files travel faster via modem which reduces time spent
sending an receiving files. BBSs (bulletin board services)
use archived files as a means to store related files with easier
access to them by way of speedier communications.
tFCB is an abbreviation for File Control Block.

Information about the status of a file is maintained by the
operating system in a block of data called a File Control Block.

FCB's are used by programs to provide the name and identification
of opened files and their status while in use.

With DOS, the traditional file services are based on FCB's. An
alternative to the FCB-oriented file services works with a 2-byte
number or 'handle' that uniquely identifies each file that is in
use by a program.
gOn a network of microcomputers, one of the workstations serves as
a hub of information. This workstation, known as the file server,
can be dedicated to its task of storing community files or it can
be designated as non-dedicated in which case it can also be
utilized as a workstation on the network.

Serving as the hub of the network, the file server also runs the
network operating system software for controlling access to the
network, and managing the electronic messages and file transfers
of the network.

As the number of workstations increases above four or five, so does
the importance of having a file server that is dedicated to the task
of managing the network. With non-dedicated file servers, just the
presence of a user application will degrade its performance. And
if the user application hangs, so does the network operating system.
êvIn DOS, filenames are from 1 to 8 characters long and can be
followed by an optional short name called an extension. An
extension starts with a period, has 1, 2, or 3 characters, and
follows immediately after the filename.

The following are examples of extensions used to identify the
type of data or the format of data to be found in the file.

.EXE Executable program, loaded to a specific memory location.
.COM Executable program, stored as an image of the program as
it appears in memory.
.BAT A batch file consisting of a series of commands
.SYS A system file, often a device driver
.TXT Often an ASCII text file created with a text editor

See the table "Filename extensions" for more examples.
%Firmware is a combination of hardware and software designed for a
specific task. It is a program and/or data stored on a ROM chip
that helps control the operation of a computer.

Firmware is non-volatile memory, which means that it retains its
contents even when the power is off, for storing information.

Electronic calculators contain firmware with the instructions for
performing the various mathematical operations.

The ROM BIOS chip in a microcomputer is an example of firmware.

PROM's, EPROM's, and EEPROM's are firmware.
^=A computer of the first generation is classified as beginning
around 1951, characterized by physically large units using vacuum
tube circuitry, stored programs, and mostly magnetic tape for
auxiliary storage.

The UNIVAC I was a first generation computer, commercially
available in 1951.

First generation computers are now museum pieces.
û,A disk or disk pack that is permanently mounted on a disk drive
is called a fixed disk.

Although fixed disks are most often found on large scale computers,
the hard disks found on personal computer systems are also referred
to as fixed disks.
³\Fixed point refers to a number system or a method of storing and
calculating numbers where the decimal point is always in the same
location for a particular quantity.

Desk calculators operate with fixed point numbers. The operator
is expected to keep track of the decimal point.

Contrast with floating point arithmetic, which is a method of
calculation that automatically accounts for the location of the
decimal point.
CA software term, a flag is a variable used in a program to indicate
whether a condition has or has not occurred.

A flag variable could be used to indicate that a record was found
to have an error in one of its fields.

A flag mechanism is used to define access privileges to a network
directory or subdirectory.
ÜIntroduced early in 1989 by Intel Corporation, the flash EPROM as
a new type of memory chip combines the flexibility of RAM with the
permanence of disks. Flash EPROMS do not need a supply of back-up
power to retain data and can be packaged like regular EPROMS and
DRAM chips.

It may be possible someday to replace the bulky, power-sapping
disk drives in computers with varieties of flash EPROMS. Laptop
computers are expected to take first advantage of these new chips.

One megabit chips were selling in 1990; two and four megabit chips
were available in 1991. When 16-megabit chips arrive in 1994,
vendors could introduce 32 MByte and 48 MByte "hard drives" on a
flash EPROM card roughly two by three inches.
?A data file that does not physically interconnect with or refer to
another file is called a flat file.

Flat files stand alone and may be created in a variety of ways.

In a relational database management system, flat files refer to
non-interconnected files.
½PFloating point arithmetic is a method of calculation that works
with number quantities that are represented by a number called the
mantissa and by a power of the number base, or exponent.

³ 283451 ³ 0 ³ 283451.0 ³
³ 283451 ³ -1 ³ 28345.1 ³
³ 283451 ³ -3 ³ 283.451 ³

The actual number is obtained by multiplying the mantissa times a
power of the number base. Notice how the decimal point floats in
the examples shown above.
žlFPU is an abbreviation for Floating Point Unit or processor.
It is a chip designed to perform arithmetic operations.

On microcomputers it may be in the form of a separate co-processor
chip or it may be part of the Central Processing Unit (CPU).
The Intel 80486 CPU has a built-in FPU.

On minicomputers and mainframes, the FPU is sometimes housed in a
separate machine often called an array processor.
;EA floppy disk is made of a flexible piece of mylar and coated with
a material that can be magnetized to store bits of data.

The most common size floppy disk is 5.25 inches in diameter and is
often used with personal computers for storing data and programs.
Floppy diskettes may be single-sided or double-sided, depending
on whether they are recorded on one or both sides. Single-sided
diskettes are now obsolete. On a double-density diskette there are
40 tracks of data; 80 on a quad-density diskette.

High-capacity diskettes have the same number of tracks as quad-
density, but they go one step further, they pack 15 sectors into
each track, instead of the customary 8 or 9.

The floppy disk was invented and patented by Dr. Yoshiro Nakamats.
See the table "Floppy Disk Specifications" for an overview.
´GFloptical disk drives for microcomputers read and write 3.5" diskettes
using a SCSI adapter. They are designed with a dual-gap read/write
head with one gap dedicated to the new floptical diskettes while the
other gap reads and writes standard 3.5" diskettes, both densities.
These drives typically out-perform standard 3.5" drives by three times.

The floptical diskettes have a storage capacity of 21 megabytes which
is achieved by combining patented optical servo positioning tracks and
magnetic recording technologies. The diskette media is barium ferrite,
a cost-effective medium for high density recording.

The Floptical Technology Association was formed in June of 1991.
WlFlow charting is the traditional way of diagramming programs.

Instructions are written into rectangles, and decision points or
branches are represented by diamond shapes. Lines connect them
together, showing the flow of control from one part of the
program to another.

Flow charts are helpful in visualizing how a program works.

ZVThe dictionary defines folio as a leaf of paper, folded once so that
it forms two leaves, or four pages. It also refers to a set number
of words considered as a unit.

In this database, the term folio refers to an idea-sized chunk of
text which generally expresses a single idea, or the definition of
a computer-related term or acronym.
.$A font is a complete assortment of print characters for a single
typeface in a single size. For example, 12-point Helvetica is a
different font than 10-point Helvetica.

Impact printers have interchangeable fonts for different character
types and sizes. On bit-mapped display systems and laser printers,
the software can define a number of different typefaces or fonts.

A font is different from a typeface.

A typeface is the design of a particular set of letters, symbols,
numbers, and punctuation marks. For example, Helvetica, Times,
Palatino, and Optima are typeface families. Each family can have
a number of different typefaces such as Times Roman, Times Bold,
Times Italic, which share the same underlying characteristics,
but require a separate design for each weight or slant.

2One footlambert equals 1 divided by pi candela per sq.ft.

A footlambert (FL) is the unit for measuring the screen
luminance of the video display.

A candela is the modern measure of luminous intensity,
roughly equal to the light given off by a candle.
,aFormatting is the process of preparing a disk so that the operating
system can find the sectors on each of the disk tracks. Formatting
also establishes the File Allocation Table.

A disk can not be used until it is formatted.

Hard disks must be initialized or "low-level formatted" before they
can be formatted. The low-level format sets up the sectors on a
hard disk and maps the bad areas for the operating system to avoid.

This process of low-level formatting is also called initializing,
physical formatting, or absolute formatting.
‰An acronym for FORula TRANslator, FORTRAN is a high-level
programming language for programs dealing primarily with
mathematical formulas and expressions, similar to algebra and
used mainly in scientific and technical applications.

FORTRAN is one of the oldest languages but is still widely used
because of its compact notation, the many mathematical subroutines
available, and the ease with which arrays, matrices, and loops
can be handled.

FORTRAN was written in 1954 by John Backus at IBM and the first
successful FORTRAN program was executed by Harlan Herrick.

Microsoft FORTRAN Version 5.1 was released in the summer of 1991.
6A computer of the fourth generation is characterized by physically
small, lower cost microcomputers using microprocessors and memory

There is disagreement as to whether this is a new generation or
merely an advanced stage of the third generation.
ûFractal geometry is a nascent branch of mathematics dealing with
irregular, convoluted, or fragmented shapes that evoke a pattern.
It was made possible by the marriage of the computer and high-
resolution graphics.

Fractals bear a striking resemblance to structures found in nature
such as cloud formations, jagged mountain peaks, the leaves of ferns.

A spectacular example of fractals is the Mandelbrot set, named for its
creator Benoit Mandelbrot, the acknowledged father of fractal geometry.
;}Fractional T-1 is a term which describes a digital communication
service provided by one or more of the 24 channels of a full T-1
line. It is a subset or fraction of the full T-1 line.

With fractional service, both the customer and the carrier company
benefit. The customer is relieved of the cost of a full T-1 line
and with multiple customers sharing one line, the carrier company
avoids wasted lines.

As a customer, whether you use full or fractional service, the
physical installation is the same.

See the definition of T-1 for further information.
‰JIn a multiprogramming environment, when memory locations not
being used are grouped together in such small numbers that they
cannot be used to store pages from other programs, main memory is
said to have become fragmented.

A disk can also become fragmented with small gaps between files.
Fragmentation is an undesirable condition and should be remedied
to free-up the unused spaces.
xUAs a type of freely-distributed software, freeware is a program
placed in the Public Domain.

It may be freely copied and passed on to others, with or without
restrictions, but unlike user-supported software, each user is not
expected to register with the author nor pay a usage fee. Often
the author will include a request for comments on the value of the
ŸFTAM is a standard specification for transferring data between
computers from different vendors.

In addition to basic file transfers, FTAM has several options,
such as reading and writing from indexed files, locating and
erasing data from indexed files, retrieving complete information
on file storage properties, retrieving file security properties,
and sending and receiving file directory information.
ÀNThe term full-duplex designates the transmission of data in two
directions at the same time as from a terminal to a computer or
from the computer to the terminal.

Full-duplex (FDX) is simultaneous two-way communication.

The term half-duplex (HDX) designates the transmission of data in
either direction but only one direction at a time.

Simplex pertains to a communications link capable of transmitting
data in only one direction.
QOn personal computer keyboards, there is a set of numbered keys
called the function keys. On most keyboards, there are either ten
or twelve keys labeled F1 through F10 or F12 which are used to
send different special purpose commands to the program in control.

Function keys can be programmed to work by themselves or in
conjunction with the Control, Alt, and Shift keys.

Some commercial programs, such as word processors, have plastic
templates to place over the function keys to identify their
special purpose.
Š,The modern practice in C-Language programming whereby a function
is more completely defined, initially, using declarators that
include information about the function parameters is referred to
as function prototyping.

In other words, when a function is initially defined, each
parameter is given a name. This approach, as opposed to omitting
the parameter names, allows the 'C' compiler to check the numbers
and types of the parameters in actual calls to the function, and
to perform proper conversions when possible.

The usage of function prototypes aids greatly in tracking down
programming errors and enhances code documentation.
@Fuzzy logic provides an approach to approximate reasoning where the
rules of inference are approximate rather than exact. Fuzzy logic is
useful in manipulating information that is incomplete, imprecise, or
unreliable. Also called fuzzy set theory, fuzzy logic extends the
simple Boolean operators, can express implication, and is used
extensively in Artificial Intelligence (AI) programs.

In the 1960s, Lotfi A. Zadeh, the father of fuzzy logic published
papers describing the idea and concepts of fuzzy logic.

Reference: AI Expert magazine, March 1992 issue.
goGas-plasma displays operate by exciting a gas, usually neon or an
argon-neon mixture, through the application of a voltage. Gas-
plasma displays use tiny pixels of gas to produce visible light,
and therefore require no backlighting. When sufficient voltage is
applied at the intersection of two electrodes, the gas glows an

Originally, gas-plasma technology provided only on-off control.
Recent advances have improved control over the brightness of the
pixels and provided several steps between the dimmest and the
brightest conditions thereby offering both 4 and 16 step "grey"
‹YA gateway provides an interconnection between two networks with
different communications protocols. A gateway is a simultaneous
interpreter between computers that speak different "languages".

Gateways operate at the 4th through 7th layers of the OSI model.

The gateway, which is provided by an adapter card in a workstation,
enables the network to perform as if it were a mainframe terminal
connected directly to the mainframe.


A PAD, packet assembler/disassembler, is a device used to interface
non-X.25 devices to an X.25 network. The PAD serves as a gateway.

Protocol converters are gateways between networks.
TMGEDCOM, an acronym for Genealogical Data Communications, is a data
file format for transferring information between genealogical computer

The GEDCOM standard was defined and is maintained by the Family History
Department of the Church of Jesus Christ of Latterday Saints (LDS).
Their large Ancestral File database accepts input and produces output
in the GEDCOM standard format.

The purpose of the Ancestral File database is to help families and
historical organizations coordinate research and reduce duplication of
effort in the process of collecting genealogical data.
#A gender mender is a special purpose cable connector for changing a
female connector to a male connector or vice versa. There are two
types of gender menders, male and female.

The male gender mender has a male connector with pins on both sides
and the female gender mender has a female connector with sockets on
both sides. When a female connector with sockets is plugged into a
male gender mender, the gender has been changed, you can make the
desired connection.

Gender menders are also called gender changers and gender benders.
jGEnie is an on-line service, a division of General Electric Company.
It claims to be the world's largest on-line teleprocessing center.
GEnie is a mainframe text-based system, organized in a hierarchy of

Services include: libraries of downloadable software, electronic
mail, conferences called round tables on computer-related topics,
multi-player games, and research capabilities.

For current fees and more information,

GE Information Services, 800-638-9636
401 N. Washington Street
Rockville, MD 20850
š0GIF is an abbreviation for Graphics Interchange Format, it is
pronounced 'Jiff'. Early in 1987, CompuServe's graphics engineers
introduced this remarkable new protocol as a standard for exchanging
raster-based images among various computers.

Some intriguing points about GIF are:

It looks to future technology by being able to preserve images
with a resolution of 16,000-by-16,000 individual dots or pixels.

While GIF can handle up to 256 simultaneous colors, the software
makes the best use of a computer's own capabilities.

GIF uses a sophisticated data compression method to reduce the
file size to less than half, saving in download time.
+oOne Gigabyte equals 1 kilobyte times 1 megabyte.
That's 1,073,741,824 bytes, or (2 to the 30th power).

'Giga' is a binary analog to the U.S. decimal unit 'billion'

The 80286 microprocessor can access 1 GByte of virtual memory.

Compact disks (CD's) have storage capacities of over a gigabyte,
that's the equivalent of fifty 20-megabyte hard disks.

A tape back-up system that claims to have the storage capacity
of 2.2 gigabytes could easily make a copy of a 2000 megabyte
hard drive.

See the Conversion Table "Bytes to Terabytes"
-cGarbage-In, Garbage-Out is a phrase that refers to the process of
submitting invalid or incorrect data to a computer program and
obtaining output results that are also incorrect or meaningless.

In the early days of computing, when people were so impressed with
the calculating power and speed of computers, they oftentimes too
quickly accepted the output of a computer program as being almost
unquestionably correct.

The phrase "garbage-in, garbage-out" caught-on in the data
processing field as a quick way of explaining the true situation.
‡HA glitch is a popular term used to describe a temporary or random
malfunction in hardware, caused by a noise pulse or stray signal.
It causes a momentary deviation from normal operation.

Problems in the software that are easily reproducible are called
bugs. But when software bugs are not well understood and not
frequently encountered, they are sometimes referred to as glitches.
=The term global denotes a complete or comprehensive coverage of a
topic or operation.

In computer programming, variables can be globally defined so that
they can be referred to from any module or routine within a
particular program.

During the use of a text editor or word processor, every occurrence
of a specified character or character string throughout the entire
text file or document can be replaced or deleted. This is referred
to as a global edit.

A global backup operation makes a copy of a complete disk.

In a spreadsheet program, a global format can be designated to apply
to every cell of the worksheet.
˜?Version 1 of GOSIP, the Government Open Systems Interconnection
Profile was promulgated as a United States federal government
information processing standard in August of 1988. Beginning in
August of 1990, all communications equipment sold to the federal
government had to comply with the GOSIP specification, which is a
subset of the OSI network model.

The main features specified by GOSIP 1 are the ability to send and
receive E-mail using MHS, and to access and transfer files using
the FTAM standard. Microcomputers are somewhat exempt because GOSIP
is only required for host systems, which are mostly minicomputers
and mainframes. However, any microcomputer linked to a host can
remotely read OSI-compliant E-mail or download files.
The organization that decides which protocols to add to the GOSIP
specification is the inter-agency GOSIP Advanced Requirements Group
in Gaithersburg, Maryland.
 The General Purpose Interface Bus is a communications standard for
sending data from the computer to a peripheral device such as a
plotter or instrumentation unit.

The GPIB was originally designed by Hewlett-Packard and is still
called the HPIB or Hewlett-Packard Interface Bus. Because of
conflicting standards from various instrument manufacturers, the
GPIB has always been difficult from a programming standpoint.

The Institute of Electrical and Electronics Engineers has now
codified the GPIB as the IEEE Standard 488.2.
ˆ*Generally speaking, microcomputers send data to the video display
screen in one of two modes, either text (character) mode or graphics

In text mode, the only characters that can be displayed on the
screen are the ASCII characters.

In graphics mode, lines and characters are drawn pixel by pixel so
that programs have unlimited flexibility in creating images on the
screen. Character attributes such as boldface and italics can be
displayed so that they appear on the screen as they do in print.

As more and more applications are written to take advantage of the
graphics mode, the text mode will become a thing of the past.
6The term grep originated in the UNIX Operating System as a search
command for locating text within data files. It is derived from the
line editor command "g/re/p", which prints all lines containing a
specified regular expression.

The text to be located can be specific or can be a combination of
certain characters and wildcard characters. The wildcard characters
can represent any digit, letter, a designated number of characters,
options, alternatives, or other specified groupings.

As a verb, the term grep refers to the process of rapidly scanning a
file or file set looking for a particular character string or pattern.
ÛYCSCW deals with the study and development of software systems that
encourage organizational collaboration, called groupware.

The purpose of groupware is to provide both structure and support
to aid us in working together with our computers as tools. One
definition for it might be "software for the group".

Groupware is not just multi-user systems such as word processing
or database systems on a network where multiple users can share
the same files. Word processing systems become groupware when
they interact with the various co-authors working simultaneously
by identifying edits by the user making them, or if they interact
with the users according to their roles: principal author,
co-author, or editor.
MTypically a GUI allows several programs to be displayed in separate
windows on the screen. The operator can move these windows around,
change their sizes, and easily switch from one program to another.
The programs have a consistent user interface that makes use of
pull-down menus, dialogue boxes, and graphical objects such as
icons, scroll bars, and buttons.

Since all screen output is in graphics mode, text can be displayed
in different fonts and sizes, and can be easily integrated with
graphical data. In addition to a keyboard, GUIs commonly support
the use of a mouse. Many of the concepts of the Graphical User
Interface were originally developed at Xerox's Palo Alto Research
Center (PARC) and first successfully brought to microcomputers with
the Apple Macintosh.

Presentation Manager is a GUI for IBM's OS/2.
The dictionary defines hacker as a slang term describing a person
who carries out or manages something successfully.

It seems that the term hacker, as applied to a computer user, first
came into use about the same time as microcomputers. A hacker is
someone who spends many hours with the computer often successfully
operating it by trial and error without first referring to the
manual. A hacker is often a technical person in the computer field,
such as an assembly language programmer or systems programmer.

Today, the term hacker has taken on a negative meaning. The news
media has often used the term hacker in a derogatory manner to refer
to people that use their technical knowledge to gain unauthorized
access into private computer systems and data banks.
õcWhen the first personal computers were introduced, the internal
disk drives were over three inches in height such that only one
could be fitted in each drive bay of the conventional desktop case.

Today, those original floppy disk drives and hard disk drives are
referred to as full-height drives. The later model drives including
magnetic tape drives and optical disk drives are designed so that
two and sometimes three devices can be mounted on top of each other
in a single bay.

A half-height drive measures only 1 5/8" high by 5 3/4" wide.

With the cases designed to stand upright on the floor, as many as
five or six half-height devices can be mounted one on top of the
other. These computer cabinets are often called tower cases.
7_A hand scanner is a hand-held device that allows the operator to
capture data into a application program. There are two kinds of
hand scanners, one for scanning text and numbers and another for
scanning graphics.

Hand scanners for reading data can be positioned and enabled to input
data as if it were coming from the keyboard. But, at this point in
time, they cannot read documents or printed information that has been
proportionally spaced, like books, magazines, and newspapers. They
can mostly read text and numbers from computer print-outs.

The graphics hand scanners are used to scan drawings, photos, logos,
and clip art. Actually they create a file of whatever is scanned,
in some graphics format for conversion and input to a desktop
publishing, word processing, or CAD application program.
Ë_A hard disk is a disk made of a rigid base, such as ceramic or
aluminum, coated with a magnetic material and having a storage
capacity measured in terms of megabytes. The rigid rotating
platter of a hard disk allows for precise data recording, high
density, and large storage capacities.

Personal computer systems for home use often will have a hard
disk with a storage capacity of 20-megabytes, 40-meg, or more.

The sort of hard disks installed on personal computers today use
a collection of methods called Winchester technology, so they are
often referred to as Winchester disks.

There are also cartridge hard disks that can be plugged in and
removed nearly as easily as a floppy diskette.
°oST506/412 - A serial hard disk interface standard developed by
Seagate Technology and used for most XT and AT hard disks.
Maximum data transfer rate is 5 megabits/sec.

IDE - (Integrated Drive Electronics) An IDE hard disk has
the controller functions on the drive itself and instead of
connecting to a controller, it attaches directly to the
motherboard. Data transfer rate is about 7.5 megabits/sec.
ESDI - (Enhanced Small Disk Interface) a standard developed by
a consortium of 22 disk drive manufacturers. The ESDI
provides for a maximum data transfer rate to and from a
hard disk of 10 megabits/sec.
SCSI - (Small Computer System Interface) a standard developed by
Shugart Associates and approved by ANSI. The parallel SCSI
uses a 50-pin connector and permits multiple devices to be
daisy chained. Data transfer rate: Up to 32 megabits/sec.
…Partitioning divides a single physical hard disk into multiple
logical partitions.

Hard disks are divided into partitions in a circular fashion. For
example, a drive's first partition might extend from cylinder zero
through 299, with the second partition beginning on cylinder 300 and
extending through 599. This circular partitioning is most efficient
since it minimizes the disk head travel when accessing data within a
single partition.
The partitions on a drive, even if there's only one, are managed by
a special sector called the partition table, which is located at the
very beginning of every hard disk. It defines the starting and
ending locations for each partition. Each partition on a hard disk
is blind to the existence of any others. By universal agreement, the
operation of software inside a partition is completely contained
within the bounds of that partition.
!/Introduced in 1985, a hardcard is a printed circuit board that
contains a hard disk and the control electronics. It plugs
into an expansion slot in the IBM-compatible microcomputers.

Hardcards are noted for their high reliability and low power
consumption partially due to the use of a voice coil actuator
type of motor rather than a stepper motor.

10, 20, 40, 80, and 105-megabyte hardcards are available for
non-volatile data storage with high-reliability. The newer
high-capacity hardcards have access times less than 10 ms.
0The physical equipment and components in a computer system are
referred to as the hardware.

Examples of microcomputer hardware:

printer modem keyboard math coprocessor display screen

hard disk scanner floppy disk plotter power supply

tape drive memory chips
9UThe originator of the de facto standard for modems in the world of
microcomputers was Hayes Microcomputer Products, Inc. In 1981, the
company produced the first modem to operate with a command set.

The set of commands that is used to control the operation of a modem
is called the standard Hayes AT Command Set. Most of the commands
are prefaced with an AT which stands for ATtention.

Today, the term Hayes-compatible is used as an adjective to describe
modems from other manufacturers that operate with the same command
set as the popular Hayes modems.
}KWhen the read/write heads of a disk drive come into contact with
the magnetic surface of a disk platter, you have a head crash.

A head crash is one of the most dreaded types of system failures
because it not only causes lost data but also damaged hardware.

A head crash is usually caused by some sort of disk contamination
or when the equipment is accidentally jolted.
œ;The term heap is often used by programmers to refer to the portion
of memory that is available after an application has been loaded.

The size of this chunk of memory may change as a program executes.
It is the responsibility of the operating system to keep track of
the location and size of all the free chunks of memory within the
heap and whether or not they are busy.

Although DOS's memory management is adequate for most needs, it is
afflicted with one problem: fragmentation. This happens when a
number of memory blocks have been allocated and freed in a random
fashion. This poor memory management could easily get you into a
heap of trouble.
¤ The technology that has vastly increased the capacity of compact
tape drives is called helical-scan recording. Originally invented
for use in broadcast systems, helical-scan recording has been used
in data storage systems since the mid 1970's.

Both longitudinal and helical-scan recording technologies rely on
magnetism to record data on back-up tapes. The basic differences
between the two are the pattern in which data is recorded and the
positioning of the heads used to read, write, and erase the data.

Conventional longitudinal recording records a track of data straight
across the width of a single-track tape, limited in size to the
width of the tape (quarter inch). Helical-scan recording packs more
data on the tape by positioning the tape at a 5-degree angle to the
recording heads. Each data track is a 3 inch long diagonal.

The magnetic tape used in helical-scan recording is of high quality.
‰tThe hexadecimal numbering system has 16 as its base, as contrasted
with the decimal system that has a base of 10.

Hexadecimal refers to whole numbers in positional notation with 16
as the base. The first ten digits are represented by 0 through 9,
and the last six digits represented by A, B, C, D, E, and F.

Computer memory addresses are conveniently expressed in hexadecimal
notation since the word length is a multiple of four. Four bits
can be expressed with one hexadecimal digit.

For example, 1011001010000111 binary is B287 in hexadecimal notation.

A hexadecimal number is the 1-byte equivalent of an EBCDIC character.
7!The Hercules Graphics Card is a video display adapter that provides
both graphics and text at a resolution of 720x348 pixels. It was
first introduced by Hercules Computer Technology in 1982 to fill a
need for clear text and graphics on a monochrome display, not then
available. It quickly became an industry standard.

Many graphic software packages are capable of operating in a mode
compatible with the "Herc card".

In 1987, Hercules introduced the InColor Card that provides for 16
colors out of a palette of 64 and uses an EGA-compatible monitor.
UA high density diskette is one which has been manufactured with a
special magnetic coating that allows a track to contain 15 sectors
rather than the 8 or 9 on the standard diskettes.

In the world of microcomputers, there are presently two physical
sizes of diskettes, the 5.25" and the later model 3.5".

With the 5.25" diskettes, the 1.2 MB floppies are high density.

With the 3.5" diskettes, the 1.44 MB floppies are high density.

These diskettes are often labeled as double-sided, high density,
or DS/HD.

See the table "Floppy Disk Specifications" for an overview.
«rThe High Sierra specification is an industry-wide format specification
for CD-ROM data. It defines the logical structure, the file structure
and the record structures of a CD-ROM disk.

It has also served as the basis for the ISO 9660, an international
format standard for CD-ROM.

The name High Sierra was taken from the place where the original CD-ROM
meeting was held in November of 1985, near Lake Tahoe, Nevada.
B8A high-level language is a programming language that is not
dependent upon the machine language of a computer, requires a
compiler to translate it into machine code, and has been
designed to allow the use of words similar to those in the
English language.

COBOL and FORTRAN are examples of high-level languages.
OeA home computer is a type of microcomputer for use in the home.

It is a personal computer, moderately priced and intended for
such activities as home management, education, record keeping,
programming, telecommunications, and entertainment.

There is a wide variety of software available designed for home
use to help manage and organize the household, such as checkbook
balancing, stock portfolio accounting, cookbook recipes, personal
calendars, and others.

The number of home entertainment and educational programs continues
to increase and improve at an alarming rate.
‡&The High Performance File System is a method of keeping track of the
location of files in directories. It was introduced with version 1.2
of the OS/2 operating system by Microsoft. It is an improvement over
File Allocation Table system used with DOS.

The HPFS supports long, mixed-case filenames. That is, unlike the
FAT, it does not restrict file naming to eight characters with a
three character extension.

The HPFS also exploits sophisticated data structures and several
levels of caching to improve performance, and allows free-form
information known as Extended Attributes (EAS) to be associated with
files and directories.
æNHST, an abbreviation for High Speed Technology, is a proprietary
signaling scheme, design, and error control protocol for high-speed
modems. It was designed by USRobotics, Inc.

HST incorporates trellis-coded modulation for greater immunity from
variable phone line conditions and asymmetrical modulation for more
efficient use of the phone channel at speeds of 4800 and above. It
also incorporates MNP-compatible error control procedures adapted to
asymmetrical modulation.
2The term "hypertext" was coined in the mid-1960's by computer
scientist Ted Nelson. The original idea of hypertexting came from
Vannevar Bush, President Roosevelt's wartime science advisor. He
proposed a machine called the "Memex" in an Atlantic Monthly
magazine article in July, 1945 titled "As We May Think".

The strict theoretical vision of hypertext proposes that every piece
of text, every word, be treated as a linkable element of an
information system. Huge amounts of data can be accessed and linked
with a few key words or data associations.

Hypertext software today supports not only links between text, but
also between graphical, video, audio, and most importantly,
executable program files in a hypertext environment to provide a
robust multi-media database.
aBoth the hardware and software for microcomputers can be described
as being IBM-compatible. It is a general term sometimes interchanged
with DOS-compatible.

When referring to a computer, DOS compatibility means software that
will run on an IBM PC and will run properly.

When discussing a plug-in board, such as a memory expansion board,
IBM-compatible means the board will work in microcomputer designed
and built by IBM.

However, devices and software may be IBM-compatible but not always
compatible with each other.
sAn icon is an image, a figure, or a representation of an object or
a process.

With programs that operate in a graphics mode, icons appear on the
screen as small symbols that can simplify access to another program,
or a certain command, or data file. Icons act as pointers.

For example, a wastebasket icon may represent the command to delete
a file. The process is activated by moving the cursor onto the icon
and pressing a mouse button or a certain key on the keyboard.

The use of icons and a mouse as a type of graphical interface
between man and machine is referred to as an object-oriented
<IDE is a hard disk drive standard interface for microcomputers.
It appeared in 1989 as a low-cost answer to two other standard
hard disk interfaces, ESDI and SCSI.

The distinguishing feature of the IDE interface is that it
incorporates the drive controller functions right on the drive.
Instead of connecting to a controller card, an IDE drive attaches
directly to the motherboard.

IDE drives offer a data transfer rate similar to the RLL ST506
type of drives, or about 7.5 megabits per second.

See the Table "Disk Data Transfer Rates" for an overview.
U$The IEEE 802 standards are a set of standards developed by the
Institute of Electrical and Electronics Engineers to define methods
of access and control on Local Area Networks.

They correspond to the physical and data link layers of the ISO
Open System Interconnection model, but divide the data-link layer
into two sublayers, the LLC and the MAC layers.
Three primary IEEE 802 Standards are in wide use:

802.3 covers bus networks that use Carrier Sense Multiple Access
with Collision Detection (CSMA/CD) including both baseband
and broadband networks. The baseband version is based on
the Ethernet network developed by Xerox Corporation.
802.4 covers bus networks that use token-passing to regulate
network access and traffic control.
802.5 covers ring networks using token passing such as token-ring.
×vAn index serves as a pointer or indicator. Consider the index finger.

An index file is a cross-reference of fields in a database file or a
cross-reference of words in a textual file. It is similar to the
index in a book. The index file provides direct access to the data
requested in a query, and for large databases is more efficient than
a sequencial search.

In programming, an index is a number or a subscript used to modify an
address, often through addition.

A clustered index is a file in which the logical, indexed order of the
key values is the same as the physical order in which the corresponding
rows exist in the table.

The preferred plural is indexes, rather than the Latin-derived indices.
s An infobase is a repository of electronic information containing
folios, references, links, and groups stored in a single computer
file. It is driven by an electronic infobase manager, a software

The information is referenced, retrieved, viewed, modified,
printed, and generally accessed with a software program
specifically designed for that purpose.
ÊiAn ink jet printer is simply a printing device that sprays one or
more colors of ink onto the paper. An ink-filled print cartridge
moves sideways in small steps as the paper scrolls through length-

Ink jet printers are not nearly as popular as dot matrix printers
but ink jet technologies are maturing and producing output quality
approaching that of a laser jet printer.

See PC/Computing magazine, NOV '90, pg 254, The Ink Jet Printer.
,Programming languages have instruction sets, the complete listing
of the instructions available to the programmer.

An instruction is a discrete step or statement in a computer program
that tells the computer to do something. It can also identify data
if required.
ƒ@An integrated circuit is a complete electronic circuit contained on
a tiny chip of silicon. Integrated circuits may consist of only a
few transistors, capacitors, diodes, or resistors, or thousands of
They are generally classified according to the complexity of their
circuitry, and the approximate number of circuits on the chip.

SSI - Small Scale Integration, 2 to 10 circuits

MSI - Medium Scale Integration, 10 to 100 circuits

LSI - Large Scale Integration, 100 to 1000 circuits

VLSI - Very Large Scale Integration, 1000 to 10,000 circuits

ULSI - Ultra Large Scale Integration, over 10,000 circuits
@HThe term interactive, when referring to a computer program or
system, indicates that the program asks questions of the user and
then takes action based on the response.

This PC-GLOSSARY is somewhat interactive in that the entries
displayed on your screen are entirely dependent on your actions
as the operator.
~+Interlacing is a technique used by some video displays in which the
electron beam repaints the screen by alternately displaying all the
odd lines and then all the even lines. Thus, interlacing updates any
single line on the screen only 30 times per second, yet it provides
a refresh rate equivalent to 60 cycles per second.


The electron beam of a non-interlaced monitor refreshes all the lines
on the display sequentially from top to bottom. Each pixel on every
line of the screen is repainted. Non-interlaced methods require
twice as much signal information in the same time frame as interlaced
The information stored on a floppy or hard disk is arranged in a
series of concentric circular paths called tracks. A single track
on a standard IBM-compatible disk contains approximately nine
thousand bytes of data. But since data is usually accessed in
much smaller chunks, each track is divided into smaller sections
called sectors, 512 bytes long. Think of a pie which has been cut
into seventeen identical, and numbered slices.
After the information contained in sector one of the current track
is read, the next sector, number 2, must be read. However, by the
time sector 1 has been moved into the CPU, the beginning of sector
two has already passed under the read/write head. There is a delay
before the disk rotates around to deliver sector 2. This problem
was resolved by spreading the sequentially numbered sectors out
around the disk. Instead of placing sector 2 immediately after
sector 1, sector 2 could be placed a few sectors later. This sector
staggering is known as sector interleaving.
{tAn interpreter is a translator program for a high-level language
that translates and executes the program at the same time. The
program statements which are interpreted remain in their original
source language, the way the programmer wrote them. That is, the
program does not need to be compiled before execution.

Each program statement is translated into machine language and
executed or processed one by one until the program is finished.

Interpreted programs run slower than compiled programs and must
always be run with the interpreter loaded in memory.

BASIC and dBase are examples of interpretive languages.
þ]A temporary halt or suspension during the execution of a task, during
which control is transferred to the operating system, is called an
interrupt. It can be caused by internal or external conditions such
as a signal indicating that an input/output device has completed the
transfer of data.

A computer's CPU has built into it the ability to be interrupted,
combined with a convenient way of putting the task that's been
interrupted on hold while the interrupt is being processed. Modern
computers such as personal computers, which are designed to use
interrupts, are called, in the terminology of circuit designers,
`interrupt driven'.

An armed interrupt accepts and holds the interruption signal while a
disarmed interrupt ignores the signal.
× IPX is an abbreviation for Internetwork Packet Exchange.

SPX is an abbreviation for Sequenced Packet Exchange.

Both IPX and SPX are network transport layer communications protocols
defined by Novell and used with NetWare, the network operating system

In conjunction with the NETx shell, IPX moves data between the file
server and the workstation by assigning source and destination
addresses to a data packet. It operates on Ethernet, ARCnet, and
Token Ring local area networks. IPX is actually a subset of the Xerox
Network Services communications protocol.

SPX is used for file access and transfer as well as other operations
requiring serialization. SPX verifies successful packet delivery.
ÃcInterrupt request lines are physical connections between external
hardware devices and the interrupt controllers. When a device,
such as a floppy controller or a printer needs the attention of the
CPU, handshaking signals are sent back and forth until a task is

On the PC and XT IBM-compatible systems, there are eight IRQ lines
numbered IRQ0 through IRQ7.
On the AT and PS/2 systems, there are sixteen IRQ lines numbered
IRQ0 through IRQ15.

In a particular system, the goal is to configure expansion boards
so that each board has its own IRQ line. If you have two serial
ports on your system, you know that IRQ3 and IRQ4 are taken.

See the table "Interrupt Request Lines"
;CISA is an abbreviation for Industry Standard Architecture.

It is an unofficial designation for the bus design of the IBM PC,
IBM PC-XT, and IBM PC-AT microcomputers and compatibles. This
original bus design allows for various adapter cards (Printed
Circuit Boards) to be plugged into expansion slots on the system
board (motherboard).

Originally introduced with an 8-bit data path on the IBM PCs and
PC-XTs, the ISA bus was expanded in 1984 with the PC-AT computer
and its 16-bit path.

ISA typically refers to the expansion slots, 8-bit or 16-bit slots.

JISAM is an acronym for Indexed Sequential Access Method. It is a
procedure for storing and retrieving data from a disk file.

When the programmer designs the format of the file, a set of indexes
is created which describes where the records of the file are located
on the disk. This provides a quick method of retrieving the data,
and eliminates the need to read all the data from the beginning to
locate the desired information.

The indexes can be stored as part of the data file or in a separate
index file.
WNThe Integrated Services Digital Network is an international
telecommunications standard that allows a communications channel to
simultaneously carry digital data as well as voice and video.

Microcomputers can communicate over ISDN at speeds up to 64 Kbps using
existing telephone wires but without a modem. An adapter card similar
to a network interface card is needed.

The Primary Rate Interface (PRI) provides services similar to a T-1
link while the Basic Rate Interface (BRI) line to your home or office
provides three digital circuits. Two of those circuits provide the
64 Kbps lines for voice and data, the third to control the ISDN circuit.

Today, ISDN only exists in a few cities but will spread quickly because
it is of particular interest to the banking and financial services, as
well as computer and communication firms.
The International Standards Organization, based in Paris, develops
standards for international and national data communications. The
U.S. representative to the ISO is the American National Standards
Institute, or ANSI.

In the early 1970's, the ISO developed a standard model of a data
communications system and called it the Open System Interconnection
model. Consisting of seven layers, it describes what happens when
a terminal talks to a computer or one computer talks to another.
This model was designed to facilitate creating a system in which
equipment from different vendors can communicate.

The other data communication models are IBM's System Network
Architecture (SNA) and Digital Equipment's DEC Network Architecture
(DNA), which both pre-dated the OSI model.
iIn relational databases, a join refers to the combination of data
selected according to specific criteria from several databases to form
a new database. Two complete tables (databases) may be joined, or
only selected fields from each.

There are different types of joining operations. An equijoin is a join
in which the new table contains two identical columns. If one of them
is removed, the result is a natural join.

An outer join includes all non-matching rows from one of the join
tables in the result table.

In a self join, column values in the same table are compared with one
another. The different instances of the same table involved in the
self join have to be aliased to distinguish them, and the column
references have to be qualified with the appropriate aliases.
NaA joystick is a two-dimensional potentiometer, an electromechanical
input device with a vertical lever, pivoted so that it may be
manipulated within 360 degrees. When connected to a computer, it
can provide positional information for the movement of the cursor
on a video display screen.

The application program that is designed to receive input from a
joystick, responds by moving a cursor or an image on the screen in
the same direction as the movement of the joystick lever.

Joysticks are connected to a computer with a cable and are primarily
used to play video games.
,Often on Printed Circuit Boards the designer will allow the board
to be set-up in a variety of ways depending on the particular needs
of the user. This is accomplished by placing a pair of jumper pins
in the circuit. If a small plastic-covered metal clip is placed
over the open pair of pins, the circuit becomes closed.

The small plastic-covered metal clips are actually electrical
conductors and are properly called shunts but are often referred to
as jumpers.

Jumpers are also called Berg post jumpers or shorting posts.
,To right justify information is to place data or text in the
rightmost position of a field or document so that the characters
are aligned to a rightmost column position when read or printed.

A word processing document that has been printed or displayed so
that the characters are evenly aligned along the right side border
is said to be right justified.

The common practice of printing information whether it be a letter,
a document, or a book, is to align the characters on the left
border, left justified.
'kKermit is a protocol designed for transferring files between micro-
computers and mainframe computers. It was developed by Frank DaCruz
and Bill Catchings at Columbia University in New York and is widely
accepted, especially in the academic world. Kermit was named after
the fuzzy, green talking frog of Jim Henson's "The Muppet Show".

There are both public domain, and copyrighted Kermit programs that
not only include the protocol but are complete programs in
themselves offering the communication functions needed for the
particular machine on which they are running.

Write for the complete Kermit protocol manual (more than 100 pgs.):

Kermit Distribution, (212) 854-3703
Columbia University Center for Computing Activities
612 West 115 Street, New York, NY 10025
+0A keyboard is an input device used like a typewriter to input data
to a computer system. Keyboards have keys or buttons labeled with
alphabetic, numeric, and special characters, such that when a key
is depressed, the corresponding character code is transmitted to
the computer program waiting to receive it.
An Enhanced Keyboard is one that contains the ten or twelve function
keys across the top and a keypad on the right.


A keypad is an input device with buttons like a typewriter but a
keypad only consists of the numbers and some special function keys,
no alphabet keys. When the operator actuates one of the buttons, a
corresponding code is transmitted to the computer. Keypads can be
found as separate input devices or, most often, added to right side
of enhanced keyboards.
2NOne kilobyte is 1024 bytes (2 to the 10th power).

'Kilo' is a binary analog to the decimal unit 'thousand'.

The size of memory in a microcomputer is measured in kilobytes,
for example, 256K, 512K, 640K.

Of course, 1024K equals 1 Megabyte.

See the Conversion Table "Bytes to Terabytes"
A kludge is a quick fix for a problem or an improvised change
in a situation to overcome a design deficiency.

A kludge is a remedy that works fine but must be pampered.
³SLaddr is a standard architecture for peripheral manufacturers
developed jointly in June of 1990 by Microsoft, Compaq, Adaptec,
NCR, and Western Digital. It is intended to provide consistency
among vendors and developers of SCSI device drivers for OS/2.

Microsoft is making Laddr a public domain product with no licensing
fees. Laddr will allow developers to write compatible drivers and
save considerable development time.
O$When two or more computers are linked together for the purpose of
sharing information and/or peripheral devices, a network is created.

When the network is confined to a geographically restricted area,
such as within the same building or perhaps on a college campus, it
is referred to as a Local Area Network.

There are three types of data transmission media used on most of
today's LANs: a twisted-pair of wires, coaxial cable, and the
newest, fiber optical cable.

There are also three basic types of LAN topologies in use today:
the ring, the star, and the bus or line.
pA laptop computer is a type of microcomputer that is designed to
be a self-contained unit, lightweight, and easily portable.

Laptop computers are often battery powered with re-chargeable
batteries. They can also be operated from an external power source.
All laptops have the keyboard and some type of video display
built-in. They also are equipped with diskette drives and often
offer hard drives as an option.

Laptop computers were popularized by Radio Shack's Model 100,
which was introduced in 1984.
–The laser printer is a peripheral device for the output of data
from the computer, one page at a time rather than a character or
a line at a time. The printed page is near typeset quality.

The laser printer is a combination of an electrostatic copying
machine and a computer printer. The output data from the computer
is converted by an interface into a raster feed, similar to the
impulses which a TV picture tube receives. The impulses cause the
laser beam to scan a small drum which carries a positive electrical
charge. Where the laser hits, the drum is discharged. A toner,
which also carries a positive charge, is then applied to the drum.
This toner, which is fine black powder, sticks only to the areas of
the drum which have been discharged. As it rotates, the drum
deposits the toner onto a negatively charged sheet of paper.
Another roller then heats and bonds the toner to the page.
Ò)A Local Area Wireless Network, as the name suggests, consists of a
group of computers linked together by radio waves or infrared light
rather than with some form of cabling.

Wireless technologies fall into three categories: spread spectrum,
narrow band, and infrared.

The concept is new and is also referred to as Wireless LAN Technology
or WIN for Wireless In-building Networks. Because of the wide range
of frequencies available, wireless networks should be able to operate
in close proximity to one another.

Initially, the data transmission speed of wireless networks is about
the same as Ethernet (10 mbps) but as the technology matures, speeds
are expected to reach up to 100 megabits per second.
ˆ7An abbreviation for Liquid Crystal Display, an LCD is a display
using liquid crystal sealed between two pieces of glass and
polarizers then activated by an external light source to form the
various characters, as on a digital watch or portable computer.

Some LCD monitors depend on the reflection of ambient light to
present an image on the screen; others increase readability by
supertwisting and backlighting the screen.

The most promising type of LCD is the recently developed active-
matrix or thin-film transistor (TFT) LCD. Within a few years, we
should see 9 and 11 inch advanced-matrix LCD monitors, monochrome
and color.
ÔAn abbreviation for Light Emitting Diode, an LED is a
semiconductor diode that emits light when a current is passed
through it and is used for alphanumeric displays on electronic
devices such as calculators.
NPrinted output from a computer that appears to have been typewritten
is referred to as letter quality.

All daisy wheel printers and most ink jet printers produce letter
quality output.

Dot matrix printers that use a 24-pin print head provide near letter
quality (NLQ) output, but the characters are not as dark and crisp.
_}A light pen is a hand-held electrical device with a light sensitive
probe or stylus, connected to the computer's graphics adapter board
by a cable to send electron beams to the adapter. They are used for
writing or sketching on the screen of a video display and provide
input to an application program.

A light pen can be used by an operator as a pointing device tool
for making menu selections presented on the video display screen.

A light pen is sensitive to receiving light as opposed to a
flashlight which shines light.

Light pens are not widely supported by software applications.
.MA linker is an executive program that connects different program
segments so that they may be combined to form one executable

A linker program often can combine compiled object modules and
assembled routines together, from different programming languages,
to create a single program.
8Linpack is a benchmark test program written in FORTRAN and used to
measure performance of a computer system in solving dense systems
of equations. It consists of a high percentage of floating point
arithmetic operations.

As it executes, it solves one hundred equations with one hundred
unknowns. Since most of the work is done in a single subroutine,
the Linpack test is mostly a measure of localized FORTRAN system
performance or the compiler's efficiency. Linpack tests are often
executed both in single precision and double precision to show the
performance of a math coprocessor chip. The results should not be
taken as a general measure of system performance.

Jack Dongarro, the author of the Linpack program acts as the single
point of contact for source, updates, and results from the Linpack.
DAn acronym for list processing, Lisp is a high-level programming
language primarily designed to process data consisting of lists.

Lisp is especially well suited for text manipulation and analysis.
It was developed and introduced in 1958 by John McCarthy of MIT.
Today, along with PROLOG, it is one of the most popular AI languages.

Common Lisp is a dialect or subset of Lisp that is intended to serve
as a standard version designed to run on a wide range of computer
systems. The U.S. Department of Defense has adopted Common Lisp as
one of its three official computer languages.

A Lisp machine is a computer designed specifically for artificial
intelligence applications and especially designed to run Lisp.

Reference: Lisp by Doris Appleby, Byte magazine, NOV 1991, pg 165.
•"The Livermore Loops benchmark test is a measure of floating point
performance. It is a FORTRAN program that contains a broad sample
of generic computations.

There are 24 kernels, each tuned to test a different performance
range of the FORTRAN development system being measured, such as,
inner products, banded linear equations, tri-diagonal elimination,
general linear recurrence, and Monte Carlo searches.

The program is maintained by the Lawrence Livermore National
Laboratory (LLNL) and is also available in the C language.

Results of the Livermore Loops test are often given in millions of
floating point operations per second, MFLOPS.
3)There are two ways to view the disk drives in your microcomputer
system, either logically or physically. When you view a drive
physically, you are looking at how many tangible drives your system
can access.

For example, if you have two hard disk drives in your system, the
first will be physical drive 1 and the second will be drive 2.
These drive numbers are the same as those referenced by FDISK and
may be logically subdivided to produce logical drives during the disk
partitioning process. Physical drives are referred to by number
while logical drives are referred to by letter.

You could have three logical drives with C and D residing on
the physical drive 1 and drive E residing on physical drive 2.
You could also have other logical drives such as RAM Disks or
remote disks in a network.
"Login, logon

The terms login and/or logon are used to describe the process of
identifying oneself to a multiuser computer system after making
a connection to it over communication lines or network cables. The
login procedure provides a means of identifying authorized users by
name and an optional password.

Logout, logoff

The terms logout and/or logoff are used to describe the process of
terminating a session with a multiuser computer system.

Logging off or out is not the same as shutting down or turning off
a computer.
.aThere is a DOS utility program called "CHKDSK" which performs an
analysis of the integrity of the files on a hard disk. If all of
the files and sub-directories are properly accounted for in the
File Allocation Table (FAT), then CHKDSK provides information about
the disk including its size, the number of files found, the amount
of storage space remaining, and other useful data.

If CHKDSK encounters a problem with one or more files, you may be
presented with a message similar to this:

"5 lost allocation units found in 3 chains.
Convert lost chains to files (Y/N) ?" See your DOS Manual.

This message indicates that portions of a file (or files) have
become detached from the rest of the file or that a file has become
separated from its directory entry. You have lost chains.
iA programming language, using symbolic code, that is based on
the machine language of a particular computer and requires an
assembler to translate it into actual machine language, is
referred to as a low-level language.

A particular computer's assembly language is always considered
as a low-level language.

The C-Language is often referred to as a low-level language but
it does not consist entirely of symbolic code. 'C' features
economy of expression, modern control flow and data structures.
úThese are logical device names for parallel printers or ports.

With DOS operating system, LPT1, LPT2, and LPT3 are reserved names
for up to three parallel printer ports. LPT1 is usually the same
as the primary DOS hard-copy output device PRN.
pComputer programs can be described as being machine dependent or
as having a certain degree of machine independence.

If the operation of a computer program relies on a particular
machine architecture or operating system for successful operation,
that program is said to be machine dependent. All assembly language
programs are machine dependent.

Most of the high-level languages, particularly the C-language, are
relatively machine independent or portable. That is, a program
written in the C-language under one operating system, such as DOS,
can often be easily transferred to a UNIX system, for example.
ÞMThe programming language comprised of a set of unique machine codes
that can be directly executed by a given computer is called its
machine language.

Machine language is the lowest level of programming. It is written
in a series of bits used to communicate primitive instructions to
the computer.

Each type of computer has its own variety of machine language.
Programmers rarely code in machine language because instructions
and data must be in binary notation.
Õ&A macro is a stored set of commands or instructions invoked by a
single command or instruction. Macro implies substitution.

One example is a keyboard macro.

If you discover a sequence of keystrokes that are used over and
over, a macro can be created which contains those keystrokes. It
can then be invoked later, often with a single keystroke, to save
time and possible errors.

As another example, a spreadsheet macro is a set of instructions
written into the worksheet that, upon execution, performs a series
of spreadsheet operations in a previously specified order. The
steps necessary to copy the values in one row to another row could
be stored a macro, and then executed with a single keystroke.
®BMag tape is an abbreviation for the various kinds of magnetic
recording tape used to store computer programs and data.
The tapes are used to store information off-line as backups.

Large computer systems and minicomputers use open reel magnetic
tapes with 7 or 9 tracks or recording channels and densities of
200, 556, 800, 1600, or 6250 bits per inch (bpi).

Microcomputers equipped with tape backup systems use magnetic
tape contained in cartridges or cassettes of many sizes.

The data that is stored and retrieved from mag tapes is done in a
sequential fashion. That is, reading or writing a specific item
on the tape requires reading everything in front of it.

A magneto-optical disc drive is a microcomputer peripheral device for
storing and retrieving data. The drive is similar to a floppy disc
drive; it can be mounted internally or reside in a external case. The
discs or cartridges are removable and come in two sizes, 3.5" and 5.25".

The 3.5" optical disc has a storage capacity of 128 megabytes with
average access times in the 30 to 60 millisecond range. The 5.25" disc
will store up to 650 megabytes on one double sided disc with average
access times in the 60 to 100 millisecond range.

Magneto-optical disc drives utilize SCSI controllers and have been in
use since 1988.
þ1The main memory of a computer is the storage area for programs,
along with its data, while they are executing.
Memory is also called RAM for Random Access Memory. The term
'random access' refers to the fact that any address in memory
can be accessed at random, or in no particular order.

The first computer memories were serial access memories, which
meant that whole sequences of data had to read or accessed
before arriving at the desired piece of information. Serial
access memories are no longer in use.

Data, temporarily stored in RAM, should not be confused with data
stored 'permanently' on a mass storage unit. Data and programs
stored in RAM are lost when the power is turned-off. RAM is
volatile, mass storage units are non-volatile.
P+Large computers are referred to as mainframes. More precisely,
the mainframe is the piece of equipment on large computers that
contains the CPU.

Mainframe computers most commonly operate with word lengths of
32-bits or more, have large memory capacities, and are used
where large volumes of data are stored and processed.

The term 'mainframe' is really a holdover from the days when
most computer systems occupied the space of several rooms. There
really was a main frame, and several secondary frames or large
rack and panel cabinets that held thousands of vacuum tubes.

:NThe Maltron keyboard layout allows potentially faster typing speeds
and is easier to learn than the traditional QWERTY layout.

The keyboard is designed so that the keys used most frequently are
positioned beneath the strongest fingers. Thus, the home keys for
the right hand are THOR and for the left hand, ANIS.

Up to eight keys are assigned to each thumb. Each key is positioned
at the correct height for the finger that uses it, thus minimizing
unnaturally long finger stretches and making the keyboard less
tiring to use than the QWERTY keyboard.

ˆOAs the name suggests, a Metropolitan Area Network is a network
that spans a region such as a city.

MANs are high-speed public networks (100 megabits/per second or
more) capable of voice and data transmission over a range of 25
to 50 miles (about 40 to 80 kilometers).

MANs often connect multiple Local Area Networks typically using
fiber optics to transmit voice and data signals.
«$A math coprocessor is a special purpose processor chip, that works
together with a general purpose or main processor, but optimized for
mathematical operations. While general purpose processors require
software routines to execute floating point and large integer
calculations, math coprocessors execute these functions in hardware,
performing the calculations many times faster than is possible with
software. In the world of microcomputers, a math coprocessor can
boost the performance of math-intensive applications by a factor of
from 10 to 100, just by adding a single chip on the motherboard.

For the IBM-compatible microcomputers, Intel Corp. designed the
8087 math coprocessor chip to work with the 8086 and 8088 micro-
processors and the NEC V20 and V30 processors.
Intel also has math coprocessors for the 80286 and 80386-based
machines. Math coprocessors, like microprocessors, come in a
variety of speeds.
RMAU and MSAU are abbreviations for Multi-Station Access Unit.
In a token ring network environment, the MAU is a multi-port
hardware device into which up to 16 workstations are connected.
The MAU provides centralized control of network connections.

The MAU moves signals from one station to the next active
station on the ring. It also provides a built-in relay to
prevent a break in network service should a single connection
or device fail. In addition to the ports for workstation
connections, the MAU has two additional ports, the RI (Ring-In)
and RO (Ring-Out) ports used to interconnect two or more MAUs.

In a coax Ethernet network, the MAU uses only one wire for both
transmitting and receiving. With 10Base-T Ethernet, the MAU
must accommodate two wire pairs, one pair for transmitting and
the other pair for receiving.
 IBM's proprietary Micro Channel Architecture is the data bus of
their PS/2 line of microcomputers. This is the data bus of the
computer that controls the flow of data between processors and to
and from such peripheral devices as the keyboard, monitor, and

The Micro Channel has three main aspects: a 32-bit bandwidth, the
I/O processors, and the multimaster control, which acts like a
data traffic cop to allow multiprocessors to work simultaneously.

The multimaster part of the bus provides the biggest benefits of
the Micro Channel. The biggest drawback to the MCA is the fact
that it is not downward compatible with IBM's earlier microcomputer
products. Boards that plug into the MCA bus are not interchangeable
with the XT's and AT's.

:iThe Monochrome Display Adapter is a single color video controller
card for the IBM-compatible computers. It was introduced by IBM
in the early 1980's to display text characters but not graphics.

The MDA generates a screen resolution of 720x350 pixels with each
character occupying a cell of 9x14 dots.

{jOne megabyte is exactly 1,048,576 bytes (1024 times 1024),
or (2 to the 20th power).

'Mega' is a binary analog to the decimal unit 'million'.

The capacity of a hard disk drive for a personal computer is
measured in megabytes, a 20-Meg drive, a 40-Meg drive.

One 'Meg' of memory is the same as 1024 kilobytes.

See the Conversion Table "Bytes to Terabytes"

'IA memory chip is a very small piece of a semiconductor, usually
silicon, on which microscopic electronic devices are formed for
storing and retrieving data bits. The number of bits that can be
stored in a single memory chip continues to grow and the speed at
which the chips operate, continues to get faster and faster.

Memory chips come in a variety of styles: DIP's, SIP's, and SIMM's.

Some of the most common memory chips in use today are the 64K, 128K,
and 256K chips operating at speeds of 150, 120, and 100 nanoseconds.

1 megabit chips are also available and by the early 1990's, 4 megabit
chips are expected to go into full-scale production.

By the mid-1990's, memory chips capable of storing 16 megabits of
data with average access speeds of 80 nanoseconds are expected.

/oMemory paging is the transfer of program segments into and out of
memory in a virtual memory environment.

With the 80386 microprocessor, a page is a 4K-byte piece of memory.
Pages are placed at locations, called page frames, whose addresses
are 4K bytes apart. A data item that starts at one of these 4K
multiple addresses is said to be "aligned on a page boundary".
Only the first twenty bits of a 32-bit page address are significant;
the last twelve are always zero.

When virtual memory is in use, pages are swapped between disk and
RAM as needed. The 4K-byte sections on disk that hold pages are
called page slots.
Memory paging can only be used in the protected mode of the 80286
and 80386 CPUs, never in real mode. Nearly all 80386 operating
systems will do at least some memory paging.
7tPrograms are referred to as being memory resident when they
remain in memory until explicitly removed or until the power
is shut-off.

Such programs are called TSR programs or pop-ups because they
remain in memory even after program termination.

TSR is an acronym for Terminate and Stay Resident.

êlWith microcomputers operating under DOS, the amount of memory that
can be utilized for working programs and data, without the use of
extended or expanded memory, is 640 kilobytes.

Extended and expanded memory are of practical benefit only if
used with software specifically written to take advantage of them.

All of Intel's microprocessor chips can utilize expanded memory
but only the 80286, 80386 and 80486 chips can utilize extended

Think of extended memory as being similar to a hard drive, all of
it is continuously available to the system. Expanded memory is
like a removable drive, the system can access only the portion
that is currently mounted and it requires a special agent to
access other portions.

÷vThe performance of a computer system is often evaluated by measuring
its operational speed in a variety of different tasks. The speed at
which a system performs floating point operations is measured in
units of Whetstones or floating point operations per second (flops).

MFLOPS then is an acronym for Millions of FLoating point Operations
Per Second.

With these benchmark tests that measure performance in Dhrystones,
Whetstones, or MFLOPS, higher numbers indicate faster performance.

1:A variety of techniques or schemes exist for writing or encoding
data to a hard disk drive.

One of the earliest and therefore the most popular techniques is
MFM or Modified Frequency Modulation
encoding. Its popularity has diminished since the introduction of
RLL data encoding formats, which allow for more data to be packed
onto the hard disk.

As the name implies, MFM is an enhancement to an earlier recording
method called Frequency Modulation. The modified FM technique
reduces the number of synchronization bits recorded on the disk.

tQMHS is an abbreviation for the Message Handling System which is
the OSI E-mail standard also known as the X.400 specification.

The purpose of this global standard is to provide a guideline for
developers of electronic mail systems. The goal is to be able to
easily send electronic information from/to any computer system in
the world with minimal conversion.

N'MHz is an abbreviation for megahertz. It is a unit of measurement.

One Hertz (Hz) is equal to one cycle per second.

Heinrich R. Hertz, a German physicist, first detected
electromagnetic waves in 1883.

Megahertz is a unit of measurement for indicating the frequency
of one million electrical vibration cycles per second.

The original IBM-Personal Computers in the early 1980's were
controlled by Central Processing Units (CPUs) that were
synchronized with clock crystals vibrating at 4.77 megahertz.

The bandwidth of your computer monitor is also measured in MHz.
½A mickey is a unit of measurement typically set at 1/200th of an inch.

It is commonly used to designate the shortest distance that a mouse
cursor can travel on the video display tube.
òHIn general, as a class of computers, the microcomputer is the
smallest and least expensive. They are fully operational and use
microprocessors as their central processing unit.

Microcomputers are used in the home as personal computers;
they are also widely used in businesses and schools.

All of the following types of microcomputers are defined in more
detail in this glossary.

Laptop computer Desktop computer Home computer

Personal computer Portable computer

ç A microprocessor is the central processing unit (CPU) of a
computer, a computer chip acting as the brains of the computer.

IBM, Compaq, and many other `IBM-compatible' personal computers
get their thinking power or instruction set from Intel's chips.
Examples are Intel's 8086 family of microprocessor chips:

³ ³ 8086 ³ 80286 ³ 80386 ³
³ Information Handling ³ 16 bits ³ 32 bits ³ 32 bits ³
³ Hardware Communication ³ 8 bits ³ 16 bits ³ 32 bits ³
³ Clock Speed (in MHz) ³ 4.77 & 8 ³ 8 to 16 ³ 12 to 33 ³
³ RAM Addressability ³ 1 MByte ³ 16 MByte ³ 4 GByte ³
³ IBM System Usage ³ PC & XT ³ PC/AT ³ PS/2,70,80 ³
³ Compaq Systems ³ Compaq ³ Compaq-286 ³ Compaq-386 ³
£cMIDI, an acronym for Musical Instrument Digital Interface.

An interface card or adapter board for connecting a musical
instrument to a microcomputer is called a MIDI Adapter. Multiple
musical instrument keyboards can be daisy-chained together and
played simultaneously with the help of the computer and related

The various operations of the musical keyboard can be captured,
saved, edited, and played back to one or more musical instruments.
Each instrument, of course, must be MIDI compatible.

Your music can be digitally recorded, then have previous tracks
played back as you record new tracks, creating the sound of an
entire orchestra.

ñlA computer that is usually more powerful than a microcomputer,
and usually less powerful than a mainframe computer is called
a minicomputer.

Minicomputers are most often found in large businesses and very
rarely found in the home.

As computers become more and more powerful each year, the exact
definitions of micro's, mini's, and mainframe computers continue
to change.

In 1959, Digital Equipment Corp. launched the minicomputer industry
with the introduction of the PDP-1.

An acronym for Million Instructions Per Second, MIPS refers to
the average number of machine language instructions a computer
can perform or execute in one second.

However, it can be shown that the same computer can execute two
different loops of code to estimate MIPS, and their execution
times will differ significantly.

MIPS should therefore be used only as a very general measure of
performance between different types of computers. In order to
obtain accurate performance data to compare similar computers,
each subsystem must be isolated, and practically speaking, this
is an almost impossible task. More realistic benchmark testing
occurs at the application level. MIPS is sometimes jokingly
referred to as Meaningless Indicator of Processor Speed.
`PA mnemonic is an abbreviated name for a computer instruction, such
as JMP, ADD, CLR, STO, INIT. A mnemonic name for an instruction
or an operation makes it easy to remember and convenient for the
translator or programmer.

Assembly language source code consists of many different mnemonics
which are translated or assembled into machine code.
~Essentially, MNP is a special error correction protocol for the
transfer of data. The protocol is implemented not through software
but as an integral part of the modem, ie. hardware.

The Microcom Networking Protocol was developed by Microcom to serve
as an industry standard for high-speed, error-free communications.

Modems that have MNP capabilities support common standards including
Bell 103, 212A, CCITT V.22, V.22 bis, and V.29. In other words,
all modem speeds from 300 to 9600 baud.

One of the problems encountered using MNP modems at any of the 6
classes is determining the particular class of MNP at which it is
operating. Also keep in mind that, for MNP to successfully work,
both the sending modem and the modem you are connected to must
have some form of MNP.
1)The term modem is an acronym for MOdulator-DEModulator.

It is a device that converts digital data from a computer or terminal
into analog data that can be transmitted over telephone lines. On
the receiving end, it then converts the analog data back to digital

A modem handles the dialing and answering of a telephone call and
generates the speed of the data transmission, which is measured in
bits per second.

Modem speeds: 300 1200 2400 9600 19200 and higher.

The telephone industry sometimes refers to a modem as a dataset.
—=A television set contains a monitor. The video screen of a cathode
ray tube (CRT) is a monitor.

There are monochrome and color monitors, for viewing the output
of a computer program.

A multi-mode monitor is a color monitor that automatically
adjusts to graphics board scanning frequencies so that it is
compatible with a variety of graphics adapters such as the
’These are four of the basic Metal-Oxide Semiconductor manufacturing
technologies. MOS refers to the three layers used in forming the
gate structure of a field-effect transistor (FET). MOS circuits
offer low power dissipation and allow transistors to be jammed close
together before a critical heat problem arises.

PMOS is a silicon-gate P-channel MOS process that uses currents made
up of positive charges. PMOS is the oldest type of MOS circuit.
NMOS is a silicon-gate N-channel MOS process that uses currents made
up of negative charges. NMOS is at least twice as fast as PMOS.

CMOS, Complementary MOS, is virtually immune to noise, runs off
almost any power supply, and is an extremely low-power circuit
technique. For these reasons, CMOS technology found its way into
microprocessors and with this advancement came the need for high-
density CMOS-compatible memory chips, dynamic RAM.
ë@The main circuit board of a microcomputer is called the motherboard.

The motherboard is a printed circuit board or system board which is
an interconnecting assembly into which smaller printed circuit
boards, or controller cards, or modules are plugged. The smaller
cards are sometimes called daughter boards.

Memory chips are often plugged directly into the motherboard or can
reside on a memory expansion card which is then plugged into an
expansion slot on the motherboard.
¡{A mouse is a small hand-held device which duplicates its movement
on a tabletop to the cursor on your screen. A mouse essentially
replaces the cursor controls (arrow) keys on the keyboard. Its
purpose is to send signals that indicate to the computer the
direction and velocity with which the mouse is being moved. A
mouse has one or more buttons that simulate certain keys. There
are basically four different types of computer mice:

The mechanical mouse uses a rolling ball, which protrudes from the
bottom to move two encoders ( for the X-axis and the Y-axis).
The wheel mouse has two wheels, each connected to an encoder, which
protrude from the bottom to rotate the encoders.
The encoders in the opto-mechanical mouse have holes that permit
light to be transmitted through them.
The optical mouse has two LEDs that generate different wavelengths
of light and associated phototransistors.
OMPC, or Multimedia Personal Computing, refers to a technical standard
set by the MPC Marketing Council, a group of hardware and software
manufacturers led by Tandy and Microsoft corporations. The standard
establishes a minimum configuration for running multimedia on MS-DOS

An MPC is an IBM-compatible microcomputer with a CD-ROM drive, audio
board, Microsoft Windows with multimedia extensions, and audio output.
The minimum hardware configuration of an MPC is a 80286 CPU running at
10 Mhz with 2 megabytes of RAM, a 30 megabyte hard drive, and a VGA

For more information, contact: Multimedia PC Marketing Council
1730 M Street NW, Suite 700
Washington, DC 20036
ñQMTBF is an acronym for Mean Time Between Failures.

MTBF is a measure of the average amount of time, usually given in
hours, that a hardware component continues to operate without
failure. For most manufacturers, it is the number of failures that
occur during the factory test period divided into the total number
of hours under observation. It could also be derived from the
results of various field testing.

For example, the average life of a microcomputer hard disk drive is
between 10,000 and 40,000 hours. That figure is based on "power on"

Keep in mind that a 40,000 MTBF number from one manufacturer could
be significantly more or significantly less reliable than a 40,000
MTBF number from another manufacturer.

tA video display monitor that is capable of automatically adjusting
to the synchronization frequency of the video board that is sending
signals to it is called a multi-synchronous monitor.

The multi-sync monitor was popularized by the NEC MultiSync monitor.

/Multitasking is an operating system feature that allows several
programs to appear to be operating at the same time. Actually a
scheduling program periodically switches between the two or more
programs, giving each a measured portion of time (time slice) to
use the CPU. True multitasking is not available under DOS.

Here are some examples of multitasking operating environments
that can run DOS programs:

DESQview by Quarterdeck Office Systems

OS/2 by IBM

Windows by Microsoft Corp.
¾ An N-type connector is a large diameter connector with threaded ends
used with both thin and thick wire coaxial cable.

N-type connectors are most often found with thick Ethernet cable.
a"Named pipes" is a software facility within the network
operating system that allows processes on separate machines to
communicate with each other across a network. It provides a
simple way for application developers to write sophisticated
distributed network applications.
One billionth of a second is called a nanosecond, that's one
thousand-millionth of a second. Sometimes a nanosecond is called
a billisecond.

The speed of logic and memory chips is measured in nanoseconds.
The RAM chips in your computer are rated in nanoseconds according
to their speed. They may be 150ns, 120ns, 100ns or 80 nanosecond

A fast microprocessor can carry out an instruction in less than
one nanosecond.

Electricity travels approximately one foot per nanosecond.

The combining form 'nano' is derived from the Greek word nanos for
dwarf and is used to designate ten to the minus ninth power.`DNAPLPS is an abbreviation for North American Presentation-Level
Protocol Syntax. It is a text and graphics data transmission
format for sending large amounts of information between computers.

NAPLPS was originally developed for videotext and teletext systems
through the Canadian Standards Association. It was later enhanced
by AT&T, and in 1983 became an ANSI standard.

For the most part, NAPLPS has been replaced on CompuServe with a
newer protocol called GIF, Graphics Interchange Format.

Commercially, NAPLPS is still alive, as a number of videotext
systems are based on NAPLPS.

ÛkGenerally, native mode refers to an operational state of a computer
that is executing a program in its native machine language.

With microcomputers, the term native mode refers to the operational
state of the computer whereby the full potential of the system is
being utilized. For example, with the new 80386 microprocessor
systems, when the resident operating system has full access to all
RAM and properly utilizes the 32-bit data bus, it is said to be
operating in native mode.

Contrast with emulation mode or protected mode.

Assembly language is sometimes referred to as native language.

A native compiler is one that produces executable code for only a
particular processor or brand of equipment.

Œ}The NCGA is a professional organization founded in 1979 that helps
to develop and promote the computer graphics industry and graphics
applications in business, science, government, and the arts.

To bring some standardization to the process of measuring a computer
system's graphic capabilities, the NCGA formed a committee comprised
of major hardware vendors. They have released a program called the
Picture-Level Benchmark (PLB) to the public domain that provides
three standardized components that can be applied to any graphical
hardware platform.

BIF - Benchmark Interface Format, a standardized file structure.
BTM - Benchmark Timing Methodology, measures response times.
BRF - Benchmark Report Format, defines a standard reporting format.

For more information: NCGA, Standards and Technical Services Dept.
2722 Merrilee Drive #200, Fairfax, VA 22031

|UContrary to popular belief, although it often refers to a certain type
of dedicated computer user, the term nerd did not originate anywhere
in the field of computers. The dictionary describes a nerd as any
person regarded as contemptibly dull, unsophisticated, or ineffective.

A nerd was first described by Dr. Seuss back in 1950. In his book
"If I Ran the Zoo", Seuss talks about young Gerald McGrew who wants to
repopulate the city zoo with the "strangest odd creatures that ever did
walk." Among them is the "Nerd," an unattractive creature with a mop
of hair, flowing whiskers, and a surly expression.

A computer nerd is similar to but not as remote as a computer geek.
A geek is one who eats computer bugs for a living, or one who fulfills
all of the dreariest negative stereotypes about hackers; an asocial,
malodorous, pasty-faced monomaniac with zero personality.
"hAn acronym for NetBIOS Extended User Interface, NetBEUI is a
network device driver or transport driver supplied with the
LAN Manager network operating system.

It is the Application Program Interface (API) that allows a program
running on a workstation access to the LAN facilities.

The NetBEUI driver can bind with as many as eight media access
control drivers.

Many vendors either provide their version of NetBEUI to interface
with their hardware or emulate its session-layer communications
services in their network products.
G/An acronym for Network Basic Input/Output System, NetBIOS is the
software originally developed by IBM and Sytek to link a PC network
operating system with specific hardware. It is the Application
Program Interface (API) that lets an IBM PC program explicitly
access the LAN facilities.

NetBIOS can also open communications between workstations on a
network at the session layer of the OSI model.

Many vendors either provide their version of NetBIOS to interface
with their hardware or emulate its session-layer communications
services in their network products.

BdWhen two or more computers are linked together for the purpose of
sharing information and/or peripheral devices, a network is created.

A network is also a database design technique for managing a
collection of related programs for loading, accessing, and
controlling the information that makes up the database.

0Inside each file server and workstation on a network, a network
interface card communicates with the network operating system
through either the NetBIOS or special driver software.

The size and on-board processing power of the network interface card
varies greatly among vendors but most have added capabilities such
as processing chips to minimize the burden on the host system.

The network interface cards and the type of cabling for connecting
the workstations to the file server go hand in hand. Cable choices
include twisted-pair telephone wire, shielded twisted-pair
data-grade wire, coaxial cable, and fiber-optic cable.
Network interface cards are used with the following types of LANs:
ARCnet, Ethernet, and Token-ring.

AT&T refers to network interface cards as Network Access Units.
åBA network operating system consists of a set of programs and related
system files that coordinate the activities of providing services to the
workstations and peripheral devices attached to a local area network.
These programs reside and execute on the file server and handle the
requests for data from all the workstations on the network.

The network operating system also performs the task of controlling
access to the network, often with a user identification and password
scheme. It also manages the details of resource allocation and sharing,
data protection, and error control.

The three most popular network operating systems in use today are:

NetWare from Novell, LAN Manager from Microsoft, and Banyan's Vines.
éNeural networking, or synthetic neurology, is the promising new
computer field dealing with the task of using computers to simulate
the processing power of the complex human brain.

Although this task is extremely complex, the first traditional
problems to be addressed will involve pattern and speech
recognition, object classification, machine learning, dynamic
adaptation, and a host of other real-world needs.

In the near future, it will be possible to design and train
synthetic neural networks to perform operations to convert written
text to speech, understand continuous unbroken speech, read poorly
written handwriting, win complex board games, and other tasks that
require a high degree of associative recognition.

¦The IBM Dictionary of Computing defines nibble as a deprecated
term for a part of a byte, usually a halfbyte. We're not sure
what they mean by "deprecated".

A nibble is half a byte or four bits.

A nibble is most often used to represent a hexadecimal digit;
however when representing a BCD value the hexadecimal values
A through F (1010-1111 binary) are not used.

Nybble is an alternate spelling for nibble.
The term NiCad is an abbreviation for nickel-cadmium.

NiCad batteries are used to provide power for today's high-tech
laptop and notebook microcomputers. They are rechargeable and
provide a relatively constant voltage which is an advantage for
voltage-sensitive computer components.

Recharged NiCad batteries are most efficient when recharged only
after they have been fully discharged. One that has been only
partially drained and then recharged will not deliver its full
rated capacity.

O Novell's NetWare, a local area network operating system, runs in the
file server and controls system resources and information processing
on the network. An NLM is a program that can be loaded and unloaded
from file server memory while the server is running.

There are basically four types of loadable modules:

û Disk drivers to control the hard disks. ( .DSK )

û LAN drivers for network boards. ( .LAN )

û Management utilities and server applications. ( .NLM )

û Name space modules for non-DOS naming conventions. ( .NAM )
‹IWhen any number of computers are connected together in a network,
each of the workstations or terminals are referred to as nodes, and
are assigned unique addresses within that network.

A node is also an electrical connection point on a printed circuit
board or component.

With database management systems, a node is a data item that can
be retrieved by two or more routes.

T$A notebook PC is a portable personal computer with the following
general characteristics.

û Battery operated, re-chargeable

û Weight: less than about 9 pounds

û Size: about 2 inches thick, 9 inches high, and 12 inches wide.

û Hard disk: 20 megabytes or more, mostly the 2.5 inch size.

û CPU speed: At least 16 Mhz
¨{NSTL, National Software Testing Laboratories

Founded in 1983, the NSTL was a pioneer in the objective and
comparative testing of microcomputer hardware and software.

Today, the NSTL is recognized as a leading independent research
organization exclusively devoted to the scientific testing of
microcomputer technology. The international headquarters in
suburban Philadelphia include a 20,000 square foot test facility
that incorporates advanced and versatile testing equipment.

The NSTL is completely independent and impartial while adhering
to a firm policy of accepting no advertising. The test reports
print exactly what the tests reveal, good and bad.

2The National Television Standards Committee governs the
standard for television and video playback and recording in the
United States.

The group was organized in 1941 when TV broadcasting first began
on a wide scale. Twenty years later higher standards were adopted
in Europe with the PAL and SECAM systems, both incompatible with
the NTSC standard of North America.

The NTSC standard (specification RS-170A) provides for 525 scan
lines of resolution and is transmitted at 60 half frames per
second. It is an interlaced signal which means that it scans
every other line each time the screen is refreshed. The signal
is generated as a composite of red, green, and blue signals for
color. It also includes an FM frequency for audio and a signal
for stereo.

The term null is used to mean empty, nothing, no information, no data,
or an empty field.

The ASCII character code for null is NUL and is represented by the
decimal number zero, but is not the same as the number zero. It is a
non-printing character.

In a Database Management System, a null field is an empty field, in
contrast to a field containing zero. Null means lack of information,
whereas zero is a number. Null fields indicate that information such
as age, year of birth, or price is not available or not reported. The
value of zero in these cases would be erroneous and could make some
statistics and comparisons unrealistic.
QNThe RS-232 standard defines two types of interfaces, data terminal
equipment (DTE), and data communication equipment (DCE).

Personal computers are almost always configured as DTE devices
while a device like a modem or mouse is typically configured as
a DCE device.
When connecting two like devices, DTE to DTE or DCE to DCE, you
must use a null modem cable or modem-eliminator adapter.

The following list shows the pin to pin connections required
to make a null modem cable between DB-25S and DB-25P connectors:

1-1, 2-3, 3-2, 4-5, 5-4, 6-20, 7-7, 20-6

ÊAn information processing technology that converts human readable
data into another medium for computer input is called Optical
Character Recognition.

An OCR peripheral device accepts a printed document as input, to
identify the characters by their shape from the light that is
reflected and creates an output disk file.

For best results, the printed page must contain only characters of
a type that are easily read by the OCR device and located on the
page within certain margins.

When choosing an OCR product, the prime consideration should be
the program's level of accuracy as it applies to the type of
document to be scanned. Accuracy levels less than 97% are often
considered poor.

Generally, any manufacturer that sells his product to a reseller
is referred to as an OEM. However, the term is also used to refer
to the reseller. In fact, OEM and VAR, Value Added Reseller, are
used interchangeably. They are relative terms.

With complex products such as computer systems, there are OEM's
and VAR's throughout the manufacturing process. No one company
manufactures all the components of a computer system, not even
the large computer corporations such as Compaq, IBM, or Tandy.

šnPronounced oh-lay, OLE is a software technology, an inter-process
communication within the Windows operating environment.

It allows the operator to embed one object within another, even
though the different types of objects may have been created using
different programs. OLE differs from traditional export/import
methods. If the embedded object is updated by the originating program,
the changes are also reflected in the embedding program.

For example, a graph from a spreadsheet can be embedded in a word
processing document. If the numbers in the spreadsheet are changed,
the updates are reflected in the graph in the word processing document.
The term on-line is used to describe equipment, peripheral devices,
and persons who are in direct communication with the central
processing unit of a computer system.

For example, a printer is described as being on-line if it is
attached, turned-on, and the on-line indicator is lit. The
printer can be taken off-line to advance the paper and still be
attached with power applied.

An on-line database refers to a file of information that can be
directly accessed by the operator.

Off-line has just the opposite meaning. Off-line storage refers
to data that has been removed from the system and stored in a place
of safe-keeping such as a library. Magnetic backup tapes are stored
ØHThe term on-line services refers to the network information services
provided by large computer systems to the owners of personal computers
with modems.
The types of services offered vary by company but may include access
to libraries of programs and data, electronic mail, on-line shopping
malls, forums, hardware and software vendor support, financial data,
stock market quotes, and research capabilities.

Further information on the following on-line services can be found
under their separate entries in the PC-GLOSSARY.

BIX, BYTE Information Exchange, DJNR, Dow-Jones News/Retrieval

CIS, CompuServe Information Services

GEnie, Prodigy, and America Online
vObject-oriented programming is a technology for creating programs
that are made up of self-sufficient modules that contain all of the
information needed to manipulate a given data structure.

The modules are created in class hierarchies so that the code or
methods of a class can be passed to other modules. New object
modules can be easily created by inheriting the characteristics of
existing classes.

The first object-oriented programming language was Smalltalk from
Xerox's Palo Alto Research Center in California.

%The operating system is the master control program that interacts
with other system and application programs within a computer.

The central core or kernel of the operating system must reside in
memory at all times. Computer programs are written to run under a
particular operating system, such as DOS, or OS/2, or UNIX.

Operating systems are also called the executive or supervisor.

ÎDOrphan and widow are word processing terms used to describe two
undesirable formatting conditions of a printed page.

The last line of a paragraph sitting alone at the top of a page of
text is called an orphan.

When the first line of a paragraph sits alone at the bottom of a
page of text, it is called a widow.

The best word processing programs have built-in features to prevent
orphan and widow lines from appearing on the printed document.

ÈFDeveloped through a joint effort by IBM and Microsoft Corp., OS/2
is an Operating System for microcomputers using either the
Intel 80286 or 80386 microprocessor chips. It is the hopeful
successor to DOS, also developed by Microsoft for IBM. OS/2 uses
the "protected mode" operation of the CPU to expand memory from
1 to 16 megabytes and for fast, efficient multitasking.

Three major components make up OS/2. At the center of the operating
system is the OS/2 "kernel". It is responsible for maintaining
files, managing several programs that may be running simultaneously,
and allowing these programs to communicate. As the second major
component of OS/2, the Presentation Manager extends the multitasking
capabilities of the kernel in order to run simultaneously on the same
screen, each program occupying its own window. The Graphics
Programming Interface (GPI), as the third major component, provides
OS/2 with a powerful graphics system.

!The OSI (Open System Interconnection) model is a reference model
defined by the International Standards Organization (ISO).

It is a communications protocol consisting of seven layers intended
as a standard for the development of communications systems

The seven layers of the OSI Model are as follows:

1. - Physical Layer wires, plugs, and electrical signals
2. - Data Link Layer packaging of data for transmission
3. - Network Layer connections between two separate systems
4. - Transport Layer conversion for transmission over network
5. - Session Layer establishes and terminates the session
6. - Presentation Layer data format conversion
7. - Application Layer messages between application programs

 An overlay is a section of a program that is temporarily stored
on a direct access storage device, such as a disk drive, while
another section of the same program is executing.

The overlay is then loaded into main memory in the same locations
occupied by the last section of the program.

Overlays are used when the program requires more memory space
than is available in main memory.

MA packet is a group of data elements transmitted together that
generally form part of a larger transmission made up of a number
of packets. A packet also contains additional information such
as packet number and error detecting codes.

Packet switching is just a method of communication that involves
splitting a transmission up into packets. Successive packets
along a given channel can belong to different transmissions.

A device used to create and unpack packets is called a PAD for
Packet Assembler/Disassembler.

ÖA value added network offering long distance computer communications
allowing the user to access a remote computer, by dialing a local
node, or access point, is called a packet switching network.

The packet switching networks use high speed digital links, which
can be land lines or satellite communications. They use synchronous
communications, usually with the X.25 protocol. The routes are con-
tinually optimized, and successive packets of the same message need
not necessarily follow the same path.

Three of the major packet switching networks are:

ARPANET, by U.S. Gov't, the first major packet switching network
Telenet, operated by General Telephone Co.
TYMNET, operated by McDonnell-Douglas

^xIn desktop publishing, and in type-setting, composition refers
to how the characters fit on the page, as well as their vertical
and horizontal spacing in relation to each other. The type font
and style determine the spacing between letters and words.

Each character has a specific width, with built-in spacing
between characters, set by the font designer. Certain pairs of
characters, such as AW and Yo, look too far apart when printed
with the built-in spacing.

Pair-kerning is a software feature that allows for the spacing
between certain characters to be adjusted before printing.

p'The terms PAL and SECAM both refer to systems of TV broadcasting
used in Europe. The NTSC system is used in North America. None
are compatible with the others.

PAL, Phase Alternating Line system, was invented in 1961 and
is used in England and many other European countries. With its
625-line scan picture delivered at 25 frames/second, it provides
a better image and an improved color transmission over NTSC.

SECAM, Sequential and Memory, is used in France and in a modified
form in the USSR. SECAM uses an 819-line scan picture which
provides a better resolution than PAL's 625-line and NTSC's 525.

FA parallel port is a channel to which a peripheral device, such as
a dot matrix printer, can be connected. With parallel transmission,
the eight bits of data representing characters are transmitted over
several lines.

The parallel port (LPT1) on the back of IBM-compatible PCs provides
a DB-25 female connector. Almost without exception, a parallel
interface in a microcomputer printer will be a Centronics interface.

Typically, a parallel transmission of data is faster than a serial
(RS-232) transmission.
[FA parity bit is a check bit appended to a unit of data to make the
sum of the total bits even or odd. If the sum of all the bits that
make-up a unit of data, including the parity bit, is even, then
that unit of data is said to have even parity. It is considered to
have odd parity if the sum of the bits is odd. A computer system is
designed to assign one type of parity throughout.

A parity check can be performed on a unit of data for either even or
odd parity to determine whether an error has occurred in the reading,
writing, or transmission of data.
A parity error occurs when the sum of the bits of a unit of data is
expected to be even but reports odd parity.

Two types of parity checks:
VRC - Vertical Redundancy Check, a parity check in transmitted data.
LRC - Longitudinal Redundancy Check, a bit positional parity check.

ßTTo parse is to separate a sentence or phase into its parts, explaining
the grammatical form, function, and interrelation of each part.

For example, a person's complete name could be parsed into its first,
middle, and last name parts.

Another example: a computer program consists of statements that must
conform to the syntax rules of the programming language. When the
program is sent to the compiler, each statement is parsed during the
syntax validation process.
Pascal is a high-level programming language, named for the French
mathematician (1623-1662) Blaise Pascal, designed to support the
concepts of structured programming, with each program following a
precise form. Pascal was developed in the early 1970's by Niklaus
Wirth for teaching programming.

Pascal is easy to learn and is often the first language taught
in schools.

Pascal is available in both interpreter and compiler form and
has more type-checking and other safety features than does the
C-Language but is generally acknowledged to be less powerful
than C.

’PA pathname is a route through the file system that leads to a file.

There are two kinds of pathnames: relative and absolute.

Relative pathnames start in the current directory and lead to a
file either residing in the current directory or in a subdirectory.

Absolute pathnames start in the root directory and always refer to
the same file, no matter where you are in the file system.

ë#PC Forth is a programming environment written specifically for the
IBM-compatible microcomputers. It is actually a superset of the
Forth-83 Standard which runs on mini and mainframe computers.

Like other Forth programming environments, it consists of more than
just a programming language. It includes an operating system, an
editor, an assembler, an interpreter, a compiler, a high-level
language, and a set of development tools or utilities.

Forth was designed and written principally by Charles H. Moore in
the 1960's. In 1976, Forth was made the standard language for the
International Astronomical Union.

For additional information on the Forth programming environments,
contact the San Diego Forth Interest Group.

ÐyPC, Personal Computer. The IBM PC microcomputer, introduced in 1981,
featured an Intel 8088 microprocessor chip, and two 360K floppy disks.

PC-XT, Personal Computer - Extended Technology

The IBM PC-XT microcomputer, introduced in 1983, featured an Intel
8088 microprocessor chip, and a 10 MByte hard disk.

PC-AT, Personal Computer - Advanced Technology

The IBM PC-AT microcomputer, introduced in 1984, featured an Intel
80286 microprocessor chip.
±UA Personal Computer is a type of microcomputer, moderately priced
and intended for an individual user at home or at the office. It is
used for a variety of tasks such as home management, accounting,
education, record keeping, programming, telecommunications, and

Adding a modem and the use of a telephone line, a personal computer
becomes a link to the outside world, capable of retrieving
information from any of the many public and private host computers.

The term Personal Computer or PC was selected by IBM as a name for
its first microcomputer product, the IBM-PC. Today, 'PC' is a
general term which applies to a wide variety of small computers.

0=PCB is an abbreviation for Printed Circuit Board.

A printed circuit board consists of a thin layer of copper bonded
to an insulating board made of phenolic or fiberglass. When
immersed in a chemical etching bath, the copper is dissolved away,
except on those areas of the board that have been coated with a
material that resists the action of the etchant. The copper left
on the board forms the wiring of the circuit.

A printed circuit is an electronic circuit that is etched, vacuum
deposited, or electroplated on a flat insulating sheet.

`The Personal Computer Memory Card International Association and the
Japanese Electronic Industry Development Association developed a
standard for integrated circuit cards called PCMCIA 2.0.

PCMCIA 2.0 establishes a standard for input/output cards and creates
a new I/O bus for portable computers. The cards are about the size of
a credit card, 85.6 by 54 mm, and are plugged into portable and
pen-based microcomputers. Cards from different manufacturers, if they
conform to the standard, can be interchanged between computers.

The cards are lightweight, small and rugged, and are used for a variety
of functions. Intel has a 2MB flash memory card. There are modem and
network interface cards. Other card peripherals for portable computers
will soon appear.
²From the Latin term, perforatus, to bore through.

Perfory refers to the rows of holes along the edges of continuous
fan-fold computer forms to allow the paper to be advanced or fed
into a printer with a tractor feed or pin feed mechanism. After
the output from the computer is printed, the perforated edges can
be removed.

Pin feed is a paper movement method that operates with a set of
pins on a platen or tractor. The pins engage the paper through
holes along the perforated edges on the left and right borders.

Printers and plotters often are equipped with a pin feed mechanism
for pulling paper into use from a roll or a continuous fan-folded
stack of paper.

+Any external hardware device used for input/output operations with
a computer system is referred to as a peripheral device.

Printers, tape drives, external modems, keyboards, plotters,
scanners, and digitizing tablets are all examples of peripheral

When a peripheral device is connected and powered is applied, it
is said to be enabled.

When a peripheral device is enabled and recognized by the operating
system, it is said to be on-line. In other words a device could be
connected and enabled but not necessarily on-line.

­}Introduced by IBM in 1984, the Professional Graphics Adapter was
designed for unusually demanding circumstances, such as Computer
Aided Design applications. It had its own microprocessor built
into it, more powerful than the computer it was installed in.

At the time the PGA provided the highest resolution with the most
number of colors (256), but was so expensive and specialized that
it never gained popularity.

wA picosecond is one trillionth of a second, abbreviated PSEC.

A picosecond is one thousandth of a nanosecond.

Pronounced 'pee-koh', the combining form 'pico' is probably
derived from the Italian word piccolo for small and is used
to designate ten to the minus twelfth power.
sPIF is an abbreviation for a Program Information File.

A PIF is a special file containing settings that tell Microsoft
Windows how to execute a non-Windows application. If a PIF is not
found for a particular application, Windows starts the application
using the standard settings. In fact, many programs never need a PIF.

PIFs can be created using the PIF Editor in the Accessories Group
within the Windows environment.

Each PIF contains two sets of options. The Standard options are for
running the application with Windows in real or standard mode. The
386 Enhanced options are for the 386 enhanced mode.
4cA pipe is a conduit or mechanism that allows the output of one process
to be used as the input to another process.

With operating systems, a pipe is a portion of memory that can be used
by one process to pass information to another.

With DOS and OS/2, pipes are symbolized by the | character embedded in
a command. For example, the command DIR | SORT | MORE calls for a
directory listing, pipes the output to the sort command, and pipes the
result of the sort command to the more command, which displays its
output on the screen, one page at a time.
íA pit is a microscopic depression in the reflective surface of
a CD-ROM disc. The pattern of pits on the disc represents the
data that is stored. The un-pitted area between pits is called
a land.

The tiny laser beam used to read the data from a CD-ROM disc is
reflected from the lands, but scattered by the pits. A typical
pit is about the size of a bacterium, 0.5 by 2.0 microns.

The term pit is broadly used to refer to any type of data-
carrying mark in optical media.

bA contraction of PICtureS ELement, a pixel is any of the tiny
rectangular elements that form a digitized picture on a video
display screen. Each pixel represents the degree of brightness
assigned to that point in the picture.

A pixel is also called a pel.

Pixel doubling is a method of changing the aspect ratio of a display
by duplicating rows or columns of pixels.

Pixel thinning is a technique for reducing the bandwidth or changing
the aspect ratio of an image by systematically discarding pixels.

( The term platform refers to the hardware architecture, the foundation
technology of a particular computer family. It is also somewhat of a
standard to which software applications are written.

For example, this program was designed and written to run on the IBM-PC
microcomputer platform.
nA plotter is an output peripheral device attached to a computer for
making drawings. There are basically two kinds of plotters, flatbed
and drum.

A flatbed plotter makes a drawing on a piece of paper placed on the
bed so that the drawing device (an ink pen or pens) must be moved
along the horizontal and vertical axes. The size of the drawing is
limited to the size of the flat bed.

A drum plotter makes the drawing from a long roll of paper of a
fixed width. The roll of paper is fed forward and backward with a
tractor feed mechanism as the pen moves left and right across the
paper in one axis.

¹-A pocket modem is a portable hardware device that plugs into a
computer's serial port to provide data communications over the
telephone lines. These units typically have a DB-25 connector
on one end and a standard RJ-11 telephone jack on the other.

Pocket modems are often smaller than a pack of cigarettes, weigh
less than half a pound, and can transmit data at speeds up to
2400 bps.

An important consideration in selecting a pocket modem is its
source of power. Some draw their power from the computer's
battery or AC while others are equipped with their own power
adapter that plugs into a wall socket. There are even some that
get their power from the telephone line.

wIn the new world of desktop publishing many of the terms are
inherited from the typesetters.

Inches are widely used in setting up page sizes and margins, but
the technical units of measure are points and picas.

The point system of type measurement was invented in 1737 by a
French typographer named Pierre Simon Fournier, and it became an
international standard. Each point is precisely .013837 inch,
which means there are 72 points to the inch. Measurements of type
height and the space between lines of type are expressed in points.

Larger measurements, such as the width of a column or page, are
expressed in picas. One pica equals 12 points. Since there
are 72 points to the inch, and 72 divided by 12 equals 6, there
are 6 picas to the inch.

ÎKA portable computer is a type of microcomputer that is designed to
be easily transported from one location to another.

The first portable computer was the Osborne I, a CP/M-based 8-bit
machine, that was soon followed by many others, such as the Kaypro,
Hyperion, and Attache. In 1982, Compaq Computer introduced the
first IBM-compatible portable computer. Even at thirty pounds, it
was very successful. Today, portable computers use flat-panel
display screens and weigh from six to twenty pounds.

Generally, portable computers are not solely battery operated,
although some may have that option. Portable computers having self-
contained rechargeable batteries are called laptops or notebook PCs.
|The terms portrait and landscape refer to the orientation of the
output on the printed page. Word processing programs often will
offer the option of printing in one of these two modes. The
portrait mode prints the regular way, so that the longest edge of
the form corresponds to the vertical axis.

³ ³ ³ ³
³ ³ ³ ³
³ PORTRAIT ³ ³ ³
³ ³ ³ ³
³ ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ The landscape mode prints sideways.

Ø}"Point of Sale" refers to the process of capturing product
information at the time and place of the sales transaction.

The two best advantages of Point of Sale systems are the
reduction of data entry errors and immediate inventory updating.

A Point of Sale system often includes an optical scanning device for
reading OCR characters or bar codes printed on the product package.
Magnetic card readers are also used to read the magnetic strip on
the back of credit cards.

The information that is collected by the Point of Sale system can
be transmitted to a central computer immediately or at the end of
some accounting period, often daily. These systems are rapidly
becoming more and more sophisticated.

ÜBoth the IBM Micro Channel and the Apple NuBus define high-level
mechanisms to integrate cards or devices into their bus systems.
This eliminates the need for jumpers or DIP switches to set either
a card's interrupt level or its address space, which is the cause
of a lot of bus problems on typical microcomputer systems.

The Micro Channel's Programmable Option Select eliminates DIP
switches from the system board and adapters by replacing them with
programmable registers.

Automatic configuration routines store the POS data into a battery-
powered CMOS memory for system configuration and operations. The
configuration utilities rely on adapter description files that
contain the set-up data for each card.

‹^Every time your microcomputer system is powered-on, it undergoes
a series of hardware checks to insure that it is working properly.
This set of diagnostic routines is called the Power-On Self-Test,
and generally, is completed within 30 seconds.

During system start-up, the POST tests the primary system board
components such as the CPU, the DMA controllers, and the interrupt
controllers. Adapters with on-board ROM modules are initialized.
The video controller card is tested and initialized. The cursor is
positioned at the top left corner of the screen. All memory chips
(RAM chips) are tested with read, write, and verify checks. The
keyboard is reset and tested. Disk interrupts are enabled.

Finally, the POST ends with a beep from the speaker and passes
control to the bootstrap loader which loads the operating system
from a floppy disk drive or from the hard disk drive.

“PostScript is a page description language developed mainly by
John Warnock for converting and moving data to the laser-printed page.

Instead of the antiquated method of transmitting simple information
to a 'dumb' printer, telling it where to place dots one-by-one on a
page, PostScript provides a way for the laser printer to
mathematically interpret and enhance a full page of shapes and
curves. There are many advantages of using a page description
language instead of bit-mapped graphics, such as smoother lines and
curves, full use of printer resolution, and the capability to
process complex fonts.
Several languages have been developed, but only PostScript really
caught on in the market and became the standard in page description.
Invisible to the user, PostScript kicks in at print time and
processes a document so that it takes full advantage of 300-dpi
(and higher) laser printers.

8In mathematics, logic, and with programming languages it is necessary
to define a set of rules governing which operations are to be
performed first. In an algebraic equation, if an expression is
enclosed in parentheses, that expression is evaluated first according
to the rules. For example, 4 x (2 + 6) = 32, but 4 x 2 + 6 = 14,
where the multiplication operator (x) is performed before the addition
operator (+).

Precedence then is a priority or hierarchy scheme for operators.

Operators used in programming languages have an inherent precedence;
that is, in the absence of explicit grouping (through parentheses),
the order of evaluation of an expression depends upon the precedence
of the elements involved. Operators of higher precedence are evaluated
before operators of a lower precedence.

^`Prodigy is an on-line service founded in 1988 as a joint venture
between Sears Roebuck and IBM. It provides a graphical interface
with CGA resolution. Commercial advertising appears on most screens.

Services include: interactive multi-player games, on-line shopping,
news, weather maps, research capabilities, and many family-oriented
features. All messages submitted to the bulletin boards by users are
edited by Prodigy to conform to its standards of good taste.

For current fees and more information,

Prodigy Services Co. 914-962-0310
445 Hamilton Avenue
White Plains, NY 10601
ætAn acronym for PROgramming in LOGic, PROLOG is a high-level
logic-based programming language used in the development of
artificial intelligence applications, such as natural language,
expert systems, and abstract problem solving.

PROLOG is designed to manipulate knowledge instead of numbers. It
is composed mainly of common English words and uses these words to
describe facts, relationships, and patterns in a logical, concise

What distinguishes PROLOG from the traditional procedure-oriented
programming languages is that each line of PROLOG includes both
instructions to and data to be managed by the computer.

PROLOG was developed in France in 1973 by Alain Colmerauer at the
University of Marseilles.

šPROM is an acronym for Programmable Read Only Memory, it is a type
of memory chip that can be programmed to a customer's needs. The
programming is done by blowing selected fuses in order to obtain
a desired bit pattern, a process called blasting. A PROM chip can
be programmed only once and is non-volatile memory.

An EPROM is an Erasable PROM, erased under high-intensity
ultraviolet light, then reprogrammed.

An EEPROM is an Electrically Erasable Programmable ROM. It is a
non-volatile storage chip. Since its contents can be erased and
then re-written under software control, it functions like a RAM chip
but is slower and more expensive.

ÃProtected memory is a property of the 80286, 80386, and 80486
Intel microprocessors that allows it to safely and reliably expand
the number of programs the CPU can be working on at one time.
That is, the protected mode allows for multitasking.

Protected memory is dynamically defined by the operating system to
erect barriers to prevent a program from interfering with the
operation of other programs or with the operating system itself.

ëAExcluding the Intel 8088, the family of 8086 microprocessors have
two modes of executing programs, real and protected mode.

In the real mode of operation, the 80286, 80386, and 80486 CPUs act
like the 8086 CPUs and execute programs one at a time in 640 K of
conventional memory. In real mode, a misbehaved program could
interfere with some other program causing the CPU to halt.

In protected mode, the CPU can safely and reliably execute more than
one program at a time. This is accomplished by the operating system
through four main facilities; protection, extended memory, virtual
memory, and multitasking.

In protected mode, DOS erects barriers to prevent a program from
interfering with the operation of any other program.
‹4A protocol is a set of rules governing the communication and the
transfer of data between two or more devices. The rules define
the handling of certain communication problems, such as framing,
error control, sequence control, transparency, line control, and
start-up control.

There are three basic types of protocol:

character oriented, byte-count oriented, and bit oriented.

/This chart shows the PS/2 line of personal computers designed by IBM
and introduced in 1987. Models 50 and above feature the MCA bus.

³ Models ³ CPU ³ Speed MHz ³ RAM ³ Hard Disk, MB ³ Slots ³
³ 25 & 30 ³ 8086 ³ 8 ³ 512/640K ³ None & 20 ³ 2 & 3 ³
³ 50 ³ 80286 ³ 10 ³ 1 MB ³ 20 ³ 3 ³
³ 60 ³ 80286 ³ 10 ³ 1 MB ³ 44,70,115 ³ 7 ³
³ 70 386 ³ 80386 ³ 16,20,25 ³ 1 or 2MB ³ 60 or 120 ³ 3 ³
³ 80 386 ³ 80386 ³ 16 or 20 ³ 1 or 2MB ³ 44 to 314 ³ 7 ³
¸>In reference to software, public domain refers to one of the types
of freely-distributed programs.

When the author or programmer of a piece of software retains no
legal rights, and has not attached a copyright notice, it is then
referred to as "public domain". Some public domain programs have
been copyrighted but do not request a fee for continued use. Anyone
may use public domain software and freely pass it on to others.

$#A pull-down menu is a window menu on the display screen that
appears to be pulled downward or expanded when an item is selected
from a line-bar menu. Menu items can be selected either with a
mouse or with the enter key.

This PC-GLOSSARY program does not make use of pull-down menus.
âInformation stored in a database file can be retrieved in a number
of different ways. In most cases, the database application program
that was used to create the database also provides a means to
selectively retrieve the information, by describing a procedure for
finding the information.

When the operator is able to define the qualifications for selected
records by specifying an example, the interactive process is called
Query By Example.

Originally, QBE as a 4th generation language was defined by M. Zloof
of IBM in the late 1970's in his paper, "Query-by-Example: A Database
Language." Today, the term is used generically to describe similar
interfaces. dBASE IV and Paradox provide interfaces in the QBE style.
üZQIC is the most common width of magnetic tape used in personal
computer tape backup systems. The width of the tape is a quarter
of an inch.

The QIC cartridges come in several physical sizes. The size of the
cartridge depends on the length, capacity, and thickness of the tape
stored inside it. Capacities vary from 40 megabyte to 1.35 gigabyte.

QIC is typically used as a prefix for a number of standards
used to promote interchangeability among tape drives from different

+Quartz is a mineral, silicon dioxide, occurring in abundance.
It is a brilliant, hexagonally shaped crystalline mineral.

For use in electronics, a quartz crystal is created by accurately
grinding and finishing a thin plate or rod of quartz. When an
electrical current is applied, the quartz crystal vibrates at a
particular frequency.

Every computer system utilizes a quartz crystal to regulate the
system clock. When the machine is turned on, electric current
causes the precisely cut sliver of quartz crystal to deform or
vibrate, at a constant rate, millions of times per second. A
voltage pulse is emitted with each vibration which, along with
other signals, controls the pace of action and ensures that the
circuits do not get out of phase.

y?Pronounced "Q", a queue is a list or temporary holding place for
data. It allows for insertions at one end and deletions at the
opposite end. Items in a queue are usually processed on the
first-in, first-out principle.

A print queue is a buffer or holding area for temporarily storing
output data directed for the printer until the printer is ready to
print it.

Z The standard typewriter or computer keyboard, with the characters
"Q, W, E, R, T, and Y" on the top row of letters as shown below.
³ ³³ Q ³³ W ³³ E ³³ R ³³ T ³³ Y ³³ U ³³ I ³³ O ³³ P ³³ ³³ ³³ ³
³ ³³ A ³³ S ³³ D ³³ F ³³ G ³³ H ³³ J ³³ K ³³ L ³³ ³³ ³³ ³
³ ³³ Z ³³ X ³³ C ³³ V ³³ B ³³ N ³³ M ³³ ³³ ³³ ³³ ³
³ ³³ SPACE BAR ³³ ³
The QWERTY keyboard was developed in the 1800's to slow-down swift
typists and to prevent jamming of the old mechanical typewriters.

§mRandom Access Memory is the type of semiconductor-based memory on a
chip in which any location can be accessed directly without having
to follow a sequence of storage locations. RAM is volatile, that is,
when the power is turned-off, the data is lost.

'Random access' refers to the ability to call up any location in
memory in the same access time, regardless of which memory location
was last accessed. Although the data stored in ROM memory chips can
also be retrieved in a random fashion, ROM chips retain their data
even after the power is off.

The term RAM is generally understood to refer to volatile memory,
in which data can be written as well as read.
9AA RAM disk is an area of memory that has been defined for temporary
storage of programs and/or data. A device driver is used to set-up
and access the data in this area in a manner similar to a hard disk
but much faster.

If your computer has extended memory (above 1 megabyte), or if it
has an extended memory board that meets EMS, you can use this area
for one or more RAM disks. Otherwise, a RAM disk can be built in
conventional memory.

When the system is re-booted, or when the power is turned off, the
information stored in RAM disks is lost.

LThe process of obtaining data from or placing data into a storage
location independent of the order of storage is called "random

For example, disk files can be created with pointers or indexes
such that data can be directly read from any location in the file
without having to start at the beginning of the file.

With memory chips (RAM), random access refers to the ability to
call up any location in memory in the same access time, regardless
of which memory location was last accessed.

ëExcluding the Intel 8088, the family of 8086 microprocessors have
two modes of executing programs, real and protected mode.

In the real mode of operation, the 80286, 80386, and 80486 CPUs act
like the 8086 CPUs and execute programs one at a time in 640 K of
conventional memory. In real mode, a misbehaved program could
interfere with some other program causing the CPU to halt.

In protected mode, the CPU can safely and reliably execute more than
one program at a time. This is accomplished by the operating system
through four main facilities; protection, extended memory, virtual
memory, and multitasking.

In protected mode, DOS erects barriers to prevent a program from
interfering with the operation of any other program.
YvA record is a group of data fields used to store information about
a particular subject. A collection of records makes up a database
file. The example shown here contains four records.

³ Record No. ³ Name field ³ City field ³ State ³ ZIPCODE ³
³ 1128 ³ Zeek Branlon ³ St.Petersburg ³ FL ³ 33710 ³
³ 1946 ³ Jim Hoff ³ Greenhills ³ OH ³ 45218 ³
³ 1948 ³ Dale Elrod ³ Medora ³ IN ³ 47260 ³
³ 191 ³ Roy K. Ahuna ³ APO San Fran ³ CA ³ 96370 ³

The record number is not necessarily part of the record but serves
as a reference and is often transparent to the user.

Record locking is a data protection scheme used by database
management systems (DBMS) to preserve data integrity in a multi-user
operating environment such as a local area network (LAN).

With record locking, it is not necessary to lock the entire database
for exclusive use by a single user, only the record being updated is
locked. This allows other users to make changes to other records in
the database simultaneously.

Early data protection schemes used file locking to prevent two or
more simultaneous update operations on a single file.

Even better than record locking, field locking schemes restrict
access only to the particular field being used. But field locking
is extremely difficult to implement and imposes a tremendous load
on the operating system.

)Referential integrity is a desirable feature of a Database Management
System. It ensures that cross-references between tables are always
valid. This is done by enforcing that foreign key values match
existing values in primary keys.

A primary key uniquely identifies a single row within a table and
can consist of one or more columns, none of which can be null.
Foreign keys point to or reference primary keys and must match those
of the primary key one for one.

An example would be a check to ensure that a customer in the database
cannot be deleted if orders exist for the customer. The advantage of
defining a check like this within the database is that the database
can enforce the check for every different kind of transaction. Thus,
it needs only to be written once.
vMemory registers are high-speed memory circuits that are integral
parts of the Central Processing Unit (CPU) chip. They are system
addresses for storing program instructions, data or addresses to
data during the execution of a program.

Assembly language programs make frequent use of the memory registers
during execution to keep track of program flow and data.

When a program halts or crashes, the contents of the registers at
the instant of the failure will provide the programmer with clues
to the cause of the problem.

¼\Resolution refers to the capability of an optical system, such as
a video screen, or of a scanning device such as an OCR, or of a
printer, of making clear and distinguishable the separate parts or
components of an object.

In video graphics, the resolution refers to the number of pixels
in which the display area can be divided, determined by the number
of horizontal and vertical pixels.

For example, a resolution of 640 by 200 pixels indicates a display
area with 640 pixels across the screen and 200 pixels vertically.
The greater the resolution, the more display memory is needed
to produce the screen image.

With high resolution printers, the output is "Letter quality".

PKA rewritable optical disk drive is a computer peripheral device for
storing large amounts of data, up to 650 megabytes on a removable

Of the three rewritable optical technologies employed today,
magneto-optical is the most developed and successful. It differs
from the traditional magnetic media in that the read/write heads
are replaced with an optical system. Information is actually
stored onto a thin magnetic film as ones and zeros similar to the
traditional hard disks, but during the read operation, the data is
read with optical lasers.

Although rewritable optical disk drives are much slower and more
costly than the traditional hard disks, they have other benefits.
The cartridges can be easily removed for safe keeping. Rewritable
optical disks are virtually free from self-erasure and head crashes.

]]REXX is a structured, procedural computer language that offers
multiple benefits not typically found in a single language. It is
used for batch, executive, and command programming. It is an
interpreted language that is readable and easy to learn.

REXX was created by M. F. Cowlishaw in 1979, at the IBM-U.K.
research laboratory near Winchester, England. It now works across a
worldwide network of IBM mainframes, minicomputers, and PCs. It
has been blessed by IBM as the command procedures language of SAA,
System Application Architecture.

As a commercial language, REXX was introduced as a system command
interpreter for the Conversational Monitor System (VMS) on IBM
mainframes in 1983. REXX migrated to the IBM PC as Personal REXX
in 1985, published by Mansfield Software Group. V2.0 supports
both DOS and OS/2 in the same package.
4,Microcomputers emit radiation that can interfere with television
reception, emergency communications, air traffic control, and
other services using electronic devices.

The Federal Communications Commission (FCC) is trying to regulate
the computer industry and protect the electromagnetic spectrum.

The most potent source of Radio Frequency Interference from a
microcomputer is the crystal that controls the microprocessor's
clock speed. But other components of a computer can cause RFI,
such as, the monitor, the keyboard, and the power supply.

A color monitor that accepts input in the form of discrete signals
for the Red, Green, and Blue guns is called an RGB monitor.

On a television or color monitor, colors are displayed as varying
intensities of red, green and blue dots. With all those colors
turned-on high, white is produced. As the intensities are equally
lowered, shades of grey are produced.

Late model RGB monitors are available in both analog and digital
varieties and can function as a computer monitor or as a television

KRISC is a acronym for Reduced Instruction Set Computer as
differentiated from CISC, Complex Instruction Set Computer.

Reduced instruction set does not mean fewer instructions, but
rather a return to simple instructions requiring only one or a
few execution cycles that are utilized more effectively under
innovative architectural and compiler changes.

As computing technology evolved, instruction sets expanded to
include newer instructions which are complex in nature and
require several to many execution cycles and, therefore, more
time to complete. Computers that operate with system software
based on these instruction sets have been referred to as complex
instruction set computers (CISC).
Systems utilizing RISC technology are able to achieve processing
speeds of up to nearly 5 million instructions per second.

ÀRJ-11 and RJ-45 are designations for commonly used modular telephone
line connectors. RJ is an abbreviation for Registered Jack.

Both of these connectors serve as an interface between the telephone
line and the receiving device such as the telephone or a modem. They
consist of a plastic plug on the end of a wire and a jack on the phone,
modem, or wall plate.

The RJ-11 consists of six wires and is used for the standard telephone
voice line connection.

The RJ-45 consists of eight wires and is typically used for data
transmission over twisted-pair telephone wire.

There are also connectors such as the RJ-16, RJ-21, RJ-27, RJ-36,
and RJ-41 for other telephone line applications.
¶JA variety of techniques or schemes exist for writing or encoding
data to a hard disk drive.
The term Run Length Limited derives from the fact that the
techniques limit the distance (run length) between magnetic flux
reversals on the disk platter.

There are several types of RLL encoding techniques:

(1,7)RLL encoding increases storage capacity 25% over MFM encoding.
(2,7)RLL or Enhanced RLL (ERLL) encoding increases storage capacity
by 50% over MFM encoding.
(3,9)RLL or Advanced RLL (ARLL) encoding roughly doubles that of MFM.

An RLL certified hard drive can use an MFM controller card but the
storage capacity and the data transfer rate will be reduced.

hRobotics is the area of artificial intelligence dealing with the
creation and use of stand-alone hybrid computer systems, called
robots, that perform physical and computational activities.

Robots are equipped with sensing devices for detecting changes in
its operational environment, a calculating mechanism for making
decisions, and with a guidance mechanism for directing its physical

Robots are used extensively in manufacturing, performing such
repetitive tasks such as welding, painting, and riveting.

ÎbRead Only Memory is the type of memory chip that can be read
but cannot be written on or altered. ROM provides permanent storage
for program instructions and is most often used in microprocessors
that always execute the same program such as an electronic game.

ROM's are prepared by the manufacturer and cannot be altered once
the chips are made.

ROM is non-volatile, that is, the data stored in ROM remains
even after the power is turned-off.

O/The root directory is the base level of the directory structure.

Branching from the root are various subdirectories, each of which can
contain one or more files and subdirectories of its own. Individual
files can also reside at the root directory level.

With DOS, the root directory of every disk drive is identified with the
backslash character (\) and is the main directory on that drive.

For example, C:\ represents the root directory of drive C:

At the DOS prompt, to change your current directory to the root
directory of drive C:, enter the following command.

çA router is an interconnection device that links complex networks
together at the network layer of the OSI model.

Routers are similar to bridges between networks but generally are
more active. They are capable of reading the network addressing
information and selecting an appropriate travel path.

Modern routers can handle multiple protocol stacks simultaneously
and move packets or frames onto the right links to their proper

A brouter is a bridge-router operating at the data link layer of
the OSI model. It performs the functions of a bridge between
similar networks but remains independent of higher protocols.
Like a router, a brouter can manage multiple lines and transmits
messages accordingly.

ÔIntroduced in August of 1969 by the Electronic Industries Assoc.,
the RS-232 interface standard provides an electrical description
for connecting peripheral devices to computers.

Although the standard specifies a 25-pin connector, not all
RS-232 devices use them. For example, the IBM PC/AT uses a 9-pin

The RS-232 standard defines two types of interfaces, Data Terminal
Equipment (DTE), and Data Communication Equipment (DCE).
Personal computers are almost always configured as DTE devices
while a device like a modem or mouse is typically configured as
a DCE device.

When connecting two like devices, DTE to DTE or DCE to DCE, you
must use a null modem cable or modem-eliminator adapter.
ÆdRTF is an abbreviation for Rich Text Format, it is a file format
defined by Microsoft as an adaption of the Document Content
Architecture (DCA) format.

RTF and DCA formats are used for transferring text documents between
applications, even those applications running on different platforms.

For example, a word processing document created with Microsoft Word
could be converted to the RTF format and transferred to an Apple
Macintosh system.
kFSAA is an abbreviation for Systems Application Architecture. It is
the formats and protocols defined by IBM for common programming
interfaces for multiple processors, enabling ease of development and

SAA defines the look and feel of software programs. It defines
specifications for programmers so that software applications will have
similar screen layouts and menus.

True SAA-compliant applications are compatible at the source level,
before being compiled, with any SAA-compliant operating system
provided the system is capable of providing all the services required
by the application.
ÿ'A scanner is a peripheral device connected to a computer to capture
graphic images from a page and convert the data into a binary code.
Once captured, the image can be edited with a painting program,
pasted into a desktop publishing document, or sent over the
telephone lines with a facsimile device.

There are four basic types of scanners; sheet-fed, flatbed,
overhead, and handheld scanners.

With the sheet-fed variety the original is fed through the scanner
by a set of rubber rollers.

More advanced flatbed scanners require that the original be placed
on a glass stage while the scanner optics take a picture of the
stationary page. Flatbed scanners can accept originals of just
about any thickness and can scan from books and magazines.

c;To advance (or go back) a specified number of lines in a file
or to reposition a graphics image that is being presented on a
display screen.

Scroll arrow

A scroll arrow is an icon that appears on the video display screen
indicating the directional movement available to the operator with
either a mouse or the cursor control keys.

Scroll bar

A scroll bar is a horizontal or vertical indicator on the screen
showing the relative position of the current screen with respect to
the overall picture. Some scroll bars contain a box that can be
used with a mouse for scrolling the screen.

Á=Small Computer System Interface is a standard developed by
Shugart Associates and approved by ANSI in 1986. The parallel SCSI
(pronounced scuzzy) permits faster data transfer than is possible
under the common serial ST506 interface used for most PC-compatible
hard disks. SCSI uses a 50-pin connector and permits multiple
devices (up to seven disk drives and/or tape drives) to be connected
in daisy chain fashion.

With a SCSI port, parallel data transfer occurs at speeds averaging
up to 4 megabytes per second.

A former name for SCSI was SASI (Shugart Associates System Interface)

The SCSI-2 bus became available in the early 1990's.

See the Table "Disk Data Transfer Rates".
îPAn SDF type file is simply a fixed-length ASCII text file commonly
used to transfer data from one computer application to another.

For example, in the dBase programming environment data files can
be input and output using this format. Each record in the file or
database is of the same length, regardless of the amount of data in
the fields that make-up each record.

The following generic dBase command will create an SDF type file:


·The SDLP specification allows software application developers
to easily interface all of the popular operating systems to
multiple peripherals that have similar but different SCSI
interfaces, such as CD-ROM devices.
³ Unix ³ ³ DOS ³ ³ Novell ³ ³ OS/2 ³ Protocol Level
³ SDLP Interface ³ Level Protocol
³ SCSI ³ ³ ESDI ³ Protocol Level
³ disks, optical devices ³ ÚÄÄÄÄÁÄÄÄÄÄ¿ Controller
³ host adapters, tape units ³ ³ disk ³ Protocol Level
ª'A computer of the second generation is classified as beginning
from the late 1950's and early 1960's. It is characterized by
physically smaller units that produced less heat and required
less power because they used solid state transistor circuitry,
and that used disks as well as tape for auxiliary storage.

From the early 1960's, the IBM 1401 and the Honeywell 400 are
examples of second generation computers.

‡7A sector is an equally spaced division of data within each track
of a disk and is the smallest unit of storage read or written by
the disk drive.

Each track consists of the same number of sequentially labelled
sectors. Thus, sector three follows sector two on each track,
and so on.

Sectors may be referred to as either physical sectors or logical
sectors. Physical sectors are the actual, sequentially numbered
divisions of the disk. Logical sectors are those that the
operating system reads and writes in sequence, a scheme that is
determined by the disk's interleave.

Floppy and hard disk sectors are 512 bytes long.

÷MGenerally, a segment is any of the parts into which a body is
separated. It refers to any partial component of a larger structure.

A segment is a portion of a computer program that may be executed
as an entity without the entire program being loaded.

In computer graphics, a display segment is a collection of elements,
such as dots, arcs, or lines, that can be manipulated as a group.

With LCD and LED displays, a segment refers to one of the bars that
make up a single character.

PA self-extracting program is one that has been created so that when
it is executed, it creates from itself one or more smaller programs
and/or data files which have been compressed inside the program.

Software developers often store and distribute programs in this
manner, thereby saving valuable hard disk space and reducing the
amount of time needed to transfer program files to other computers.

Self-unARCing is a another term that also refers to the process of
extracting data from a file created with the archive program called
ARC from System Enhancement Associates.

o#A semaphore is a programming or software term.

A semaphore is often a flag variable used to indicate whether a
shared resource can be accessed.

Semaphores are also useful in providing synchronization between
two or more threads or processes that are being executed at the
same time. Multitasking operating systems, like OS/2, make use
of semaphores.

ÉA semiconductor is a substance, such as germanium or silicon,
whose conductivity is poor at low temperatures, but is improved by
minute additions of certain substances or by the application of
heat, light, or voltage. Depending on the temperature and pressure,
a semiconductor can control a flow of electricity. It is the
material from which integrated circuits are made.

Semiconductors are the basis of modern electronic circuit technology.

cdWhen a file must be read serially from the beginning to the end,
it is described as being a sequential access file.

For example, magnetic tape files must be searched serially from
the beginning to find the desired record.

Data from disk files can be read in a sequential or random manner
depending on how the file was designed and written.

ì1A serial port is an asynchronous communication channel or address to
which a peripheral device such as a modem, a character printer, or a
mouse, can be connected.

Serial ports are also referred to as COM ports, (COM1, COM2, etc.)

With serial communications, bits of data are transmitted one
at a time over a single line as opposed to parallel communications
where multiple wires in the cable allow data to be sent in multiple

Serial interfaces are also called RS-232.
YrWith random access memory (RAM), stored information can be accessed
directly and quickly without having to follow a sequence of storage
locations, regardless of which memory location was last accessed.

The system BIOS (Basic Input/Output System) is responsible for
handling the details of the input and output operations, including
the task of relating a program's logical records to a peripheral
device's physical records.

Shadow RAM is a technology that loads the system BIOS and/or video
BIOS into RAM during the boot procedure, thereby allowing the BIOS
to operate much faster.

ÃHShareware is a distribution method for software programs developed
by independent programmers or authors. It is a marketing technique
rather than a type of software. It allows the author to market the
program with minimal start-up expenses while encouraging feedback
from the users.

Programs acquired through the Shareware method may be freely copied
and passed on to others, but each user is expected to register with
the author and pay a usage fee. The fee may include some or all of
the following: printed documentation, the latest version of the
program on disk, telephone support, free updates, and commissions,
but most importantly a legal license to continue using the software.

O*A sheet feeder is a mechanical device that feeds individual sheets
of paper into a printing device, one at a time.

Sheet feeders are available for standard and legal size forms and
are commonly found on copy machines and computer printers.

Envelopes can even be used with sheet feeders for printing names
and addresses.

S:In reference to software, the term 'shell' refers to the specialized
program that allows the operator to enter commands and access the
system resources. Known as the command processor, or shell, it is
simply a user interface to the operating system, not the operating
system itself.

For example, the familiar default command processor for DOS is
COMMAND.COM. You can change the default shell for DOS with the
following statement in the CONFIG.SYS file. SHELL=C:\DEBUG.COM,
and you will be presented with the DEBUG dash prompt instead of
COMMAND.COM's familiar prompt. But since DEBUG wasn't written as
a shell, when you quit, your system will be hung-up.

Another example: The OS/2 shell program that loads when you boot
is called the Program Selector. You start OS/2 sessions or run
the DOS box from the Program Selector.

9fA Special Interest Group consists of a number of people within a
larger organization who share the same interest in a particular
topic or subject.

Special interest groups often hold their own meetings, sponsor
exhibits, publish documents, and/or administer forums related to
their special topic.

Computer clubs and Bulletin Board Systems most often will have
SIG'S for members interested in applications such as spreadsheet,
database, programming languages, genealogy, communications, desktop
publishing, accounting, CAD/CAM, networking, and others.

Ë.Memory chips are available in a variety of styles:

The Single In-line Package (SIP) is a single package array of
computer chip logic assembled so that all the connecting legs
are in a straight line, like the teeth on a comb.

The Dual In-line Package (DIP) is the traditional computer chip
with 8, 14, 24 or even 40 or more metal legs or prongs, evenly
distributed on the left and right sides.

The Single In-line Memory Module (SIMM) is a type of memory chip
design whereby individual logic devices are installed on a printed
circuit board, creating a component module that can be plugged into
a larger device. A SIMM holds nine DRAM chips, eight for data and
one for parity or error checking.
1All the programs, languages, and/or routines that control the
operations of a computer are referred to as the software.

The software for a computer system is most often loaded into the
computer from a disk or magnetic tape but it can also be built into
a computer ROM (Read-Only Memory) chip.

%KMaking un-authorized copies of computer programs for distribution
to others is called software piracy.

This illegal practice is very common in the microcomputer world
and has caused software developers to devise all sorts of preventive
methods. But over the years, as each new copy protection scheme was
introduced, a counter method was devised.

By the late 1980's, copy-protected software was mostly a thing of
the past. But that doesn't make it legal to freely copy software.

Large software-producing corporations are very serious about trying
to minimize software piracy. In fact, there is an association in
Washington D.C. called the Software Publishers Association. They
maintain a toll-free telephone number (800-388-7478) for the
purposes of reporting software piracy.

PAlong with the growth and popularity of microcomputers, especially
in the mid to late 1980's, a nasty side effect also came into
existence, the software virus. It is any program written expressly
for the purpose of reproducing itself after or during the process
of committing some act of malice on the infected system.

Some virus programs immediately erase all files on a hard disk
while others will lay dormant sometimes for months before causing
any damage. There are, of course, programs available for detecting
the presence of viral software or preventing them from infecting a
system. These anti-viral programs often require continual RAM
residency and can sometimes erroneously alert their owner to
questionable but benign behavior of non-viral software.

For more info, contact the National BBS Society, (408) 727-4559.
B+When a programmer writes a computer program, the statements that
make up the program are saved in a disk file. The disk file is then
referred to as the source code (or source file).

The term source code refers to any computer program written in any
programming language. In fact, in the spoken word, programmers often
refer to the source code as the source; as in "Let's take a look at
the source."

If the program contained in the disk file is printed to a hard copy,
the output is called the source code listing, which is just another
name for program listing.
¡DIn a networking environment, some token ring bridges, notably
those from IBM, use an intelligent data transmission scheme called
source routing for sending packets of information from a workstation
on one Local Area Network to another.

The packet contains routing information specifying the LANs and
the bridges through which it will travel to its destination. The
sending machine is responsible for putting this information in the

Source routing diminishes network performance slightly but this is
offset by the fact that the sending machine can choose the optimal
path at the time of transmission. This is not possible with
transparent routing.
xgThe acronym "spool", for simultaneous peripheral operation on-line,
was first used by IBM for its 7070 mainframe computer in the early

With microcomputers, spooling refers to a printing operation taking
place in a background mode while allowing the operator to perform
another task.

Spooling originated with mainframe computer operations in which data
on low-speed input and output devices was transferred to disk first
and then fed to the central processor at high speed.

Spooling programs monitor the activity of shared peripheral devices
and schedule their tasks based on the priority of the data.

ë+A spreadsheet is a computer program that allows the user to set-up
a matrix of cells and to define the relationships between all the
elements. Changing a value in one cell will then alter automatically
the values of all other cells that are mathematically linked to it.

This degree of flexibility allows the user to play 'what-if'
speculation, with the results of the experimentation visible on
the screen immediately. The original spreadsheet program is called
VisiCalc, conceived by Dan Bricklin, and introduced in 1978 for the
Apple II computer.

Other popular spreadsheet programs:

LOTUS 1-2-3 Framework SuperCalc Lucid 3-D ProQube

QUATTRO PlanPerfect Excel VP-Planner Plus SmartWare

É`A battery operated device that supplies a computer system with
electricity in the event of a power failure or an unacceptable
voltage level, is called an Stand-by Power Supply.

A stand-by power supply switches to battery backup power for a
limited time so that the computer can be powered down in an orderly
fashion. One of the key factors to consider before purchasing a
stand-by power supply system is the amount of time required to
switch to the battery backup power.

Better than a SPS is a true Uninterrupible Power Supply, which
always supplies power through a battery even when commercial power
is available. There is no switching back and forth between battery
and commercial power.

+SQL is a standard database language supporting query processing
transactions, data management security, data integrity, and recovery.

In the early 1970's IBM mathematician E.F.Codd described a relational
database model consisting of one foundation principle and 12 related
rules specifying explicit characteristics that a relational system
must have. The foundation rule states that any system claiming to be
relational must be able to manage data entirely through relational

Most microcomputer database products on the market today do not meet
half the rules and are therefore not considered fully relational.
SQL however, is used extensively on mid-range and mainframe computers
and is rapidly becoming commonplace in the micro world.
_SRAM is an acronym for Static RAM and is pronounced 'ess-RAM'.

SRAMs are semiconductor memory chips based on the logic circuit
known as a flip-flop instead of capacitors like DRAM chips. Although
the static RAM chips require power to hold their information, they do
not need to be continuously refreshed like DRAM chips.

SRAMs are faster than DRAMs but can only store about one-quarter
the amount of data as DRAMs of the same complexity. They are more
expensive than DRAM chips.

Static RAM memory chips have access times between 10 and 30
nanoseconds and are often used for memory caches.
&sThese abbreviations are found on the diskette packages and often
on the diskettes. They refer to the number and type of magnetic
recording surfaces.

SS/DD - Single-Sided, Double Density, 5.25" disks, 160 Kilobytes
rarely used, not sold in stores anymore.

DS/DD - Double-Sided, Double Density, 5.25" disks, 360 Kilobytes
3.5" disks, 720 Kilobytes
DS/HD - Double-Sided, High Density, 5.25" disks, 1.2 Megabytes
3.5" disks, 1.44 Megabytes

The double density recording technique is now standard. The high
density diskettes require high density drives, which can read at
both the standard and the high density. For example, the high
density 3.5" drives can read and write double density diskettes.
H/The ST506 was pioneered by Seagate Technology with the 5-megabyte
hard disk drive. It was derived from two other interfaces: the
SA1000 for 8-inch drives and the SA450 for 5.25" floppy disk drives.

The ST506 interface requires that the read-write head be stepped or
moved across the disk one track at a time by carefully timed pulses.
Since these pulses actually cause the read-write head's stepper
motor to advance a notch, they cannot proceed faster than the disk
drive can move the head.

The ST412 interface introduced an enhancement that eliminated this
problem, the buffered seek. Instead of requiring the controller to
slow the pulse rate to whatever the mechanism could handle, the
ST412 simply counts the pulses as they come in. It then decides
how fast to step the head to move the required number of tracks.
xQA stack is a set of hardware registers or a reserved amount of main
memory that is used for arithmetic calculations or for keeping track
of internal operations. Stacks are used to keep track of the sequence
of routines that are called in a program.

The operating system and a program can maintain one or more separate
stacks. Stacks normally work on a Last-In-First-Out (LIFO) basis.
The last item, or address, placed or pushed onto the stack is the first
item removed or popped from the stack.

A stack pointer is a register or address that identifies the location
of the most recent item placed on the stack.
¾QA stationary form of electricity, static electricity is produced
whenever positive and negative charges are separated by friction,
pressure, heat, or induction. The separation produces a voltage,
and when the voltage exceeds the insulating potential of the medium
separating the oppositely charged particles, a discharge occurs as
the particles rapidly come together.

Static electricity can be easily built up on your body as you walk
across a carpeted room. When you touch the metal case of your
microcomputer, the charged particles are attracted to the charge
"sink" provided by the grounded metal case. Fortunately, no damage
is likely to occur to the sensitive components.
However, if you are working with unprotected components such as
memory boards, memory chips, math co-processors, or any printed
circuit boards, the static electricity that may build up on your
body could definitely damage or zap these sensitive components.

µZAlso called page-mode RAM, static-column RAM is a memory design
whereby system RAM is divided into equally sized areas, called
pages, using column addresses.

Static-column RAM requires a special static RAM chip (SRAM) which
is more expensive and harder to find than ordinary DRAM.

On 386-based computers that use memory paging, each bank of RAM
(usually 1MB or 4MB in length) is logically divided into rows
and columns.

YStopbits is a data communications term used to distinguish where one
character stops and another starts in the process of a serial data
transfer. Data communication programs normally add one, or sometimes
two stopbits on the end of each character.

The term databits refers to the number of bits used to define a
character during serial data transmissions, usually 7 or 8.

When connecting two computers together via the communications ports,
it is necessary to set the same number of stopbits and databits at each

For example, during the setup process for a communications program the
number of stopbits and databits need to be specified for each different
BBS or On-Line Service. For most BBSs, the stopbits parameter is set to
one and the databits parameter is set to 8.
ƒyStreaming tape is magnetic tape that is sometimes used to backup
data stored on hard disks.

The name streaming tape derives from the fact that such systems
often operate in a continuously running, or streaming mode, with
data stored or retrieved while the tape is running.

Quarter inch tape cartridges are often used with personal computer
streaming tape backup systems.

UCStructured programming is a discipline in which each sequence of
program instructions performing a specified logical procedure is
viewed as a separate unit with one entry and exit point, so that
the program can be followed as a series of processing steps and be
easier to understand.

Good structured programming practices lead to reduced cost in
program modification and maintenance as well as in the original

Technical conferences or reviews intended to analyze program
design, detect errors, and exchange knowledge and ideas are
called structured walk-throughs.

Á/A subdirectory is an area on a disk for storing files. Subdirectories
consist of files and/or other subdirectories.

A directory listing will show the names of files and subdirectories
subordinate to that subdirectory along with file sizes, creation dates
and times.

Each formatted disk contains a main directory also called the root
directory. With DOS, the most common hard disk root directory is
referred to as "C:\" or just "C:".
Q<A subroutine is a group of program instructions that stand-alone and
perform a specific processing function.

Subroutines are called from main programs or from other subroutines.
The major reason for using subroutines is that they are coded and
debugged once but may be called and executed from many different
points in a program.

Subprograms, functions, macros, procedures, and program modules are
all subroutines.

A good example of a subroutine is a group of program instructions to
calculate the square root of a number and return the answer to the
calling program.

[$As a standard introduced by IBM in 1987, the VGA, Video Graphics
Array provides for a screen resolution of 640 x 480 pixels.

Super VGA, introduced a year later offers a resolution of 800 x 600.

And then, along came super-extended VGA, or 1K-resolution VGA, at
1024 x 768 pixel resolution.

See the Table "Video Display Standards"

xA surge protector or surge suppressor is an electrical device that
is placed between sensitive electronic equipment and the source of
the electrical energy, usually a wall socket. This inexpensive
device protects the electronic equipment from an over-supply of
voltage on the incoming lines of the power company. Lightning is
a common source of power surges or spikes.

What happens when a voltage spike comes down the line ?
If the spike is strong enough, the protective circuitry in the surge
protector blows and prevents any further electrical power from
reaching the sensitive equipment. For continued protection, another
surge protector must be installed.

A surge protector is not designed to protect from decreased voltages
caused by brownouts. Protection from both high and low levels of
voltages can be provided by a power line filter or voltage regulator.
ÚwThe term synchronous is used to designate events occurring at
timed intervals regulated by pulses from the computer clock.

A synchronous transmission is a communications mode in which a
clock signal is transmitted with the data at precisely defined
time intervals, to maintain the receiver and transmitter in

In synchronous transmissions, since events take place at fixed
times, the completion of preceding events need not be acknowledged.

=Every computer programming language has rules about how its
commands and instructions should be written and in what order.
These rules make-up its syntax.

The syntax of a programming language is checked by that language's
compiler at compilation time.

±1The term SysOp stands for System Operator and, in the world of
microcomputing, refers to the person responsible for maintaining
a Bulletin Board System (BBS).

The job responsibilities of a SysOp can be quite involved. On
some BBS's, the SysOp acts not only as an administrator, file
manager, and librarian, but also as a mediator for the various
electronic meetings or conferences that may be taking place on
the BBS.

)-T-1 is an AT&T term that describes a communications circuit or a
data-carrier facility which consists of a cable and its hardware.
T-1 is a service provided by long distance communications carriers
for the transmission of digital signals whether voice, video, or
data. A T-1 carrier can transmit large volumes of information across
great distances at high speeds and at a lower cost than traditional
analog leased-line services.

A full T-1 line is a 4-wire circuit (two pairs of normal twisted
wires) providing 24 separate 64 Kbps logical channels. The total
capacity of a single T-1 line is the sum of its 24 subchannels, plus
8 Kbps overhead, for a total of 1.544 megabits per second.

T-1 is a standard for digital transmissions in North America and is
not compatible with T-1 in Europe.
ïkCopies of data and program files are called backups. Most backup
systems fit into one of two categories; tape or disk.

With microcomputers, tape backups can be performed on systems with
hard disk drives and an internal or external tape backup drive.
Most tape drives for microcomputers use a magnetic tape cassette or

There are generally two types of tape backups, image and file-by-file.
An image backup operation creates one dataset on the magnetic tape,
containing all the information that was on the disk drive.

A file-by-file backup allows the operator to select certain files
and/or subdirectories from the disk to be backed-up. Not all backup
programs allow individual files to be restored from image backups.
Ú7TCP/IP is short for Transmission Control Protocol/Internet Protocol.

It defines certain network rules developed by the U.S. Department of
Defense. Actually, both TCP and IP are protocols contained within
the larger set of Defense Data Network protocols. It is an
implementation of two layers of the OSI Model.

TCP breaks data transmissions up into packets, reassembles them at
the other end in the correct order, and re-sends portions that do not
transmit correctly. IP, the internet protocol, is responsible for
the actual routing and transmission of the data.

TCP/IP provides networked users with the following services:
File transfer, remote login, E-Mail, remote job execution, and
server functions.

k!One TB equals 1MB times 1MB. (2 to the 40th power)

or 1,099,511,627,776 bytes.

'Tera' is a binary analog to the decimal 'trillion'.

The 80386 microprocessor can access 64 TB of virtual memory.

Terabytes are used to measure the storage capacities of optical
disks, mass data storage devices.

See the Conversion Table "Bytes to Terabytes"

6A terminal is a device used by a person to send data to and
receive data from a computer system. It consists of a keyboard
and a CRT and/or printer and can be located at great distances
from the computer, connected by any of various communication

A terminal differs from that of a personal computer's monitor
or video display.

A personal computer together with its video components, however,
has the potential to serve as a terminal for another computer.
This process is called terminal emulation.

In addition to computers, mainframe and minicomputer manufacturers
also produce a wide variety of peripheral devices. The terminal is
one such device. It is used for data input and output and normally
has a keyboard for input and a video screen for output. Oftentimes
these computer systems or certain programs will only communicate
through a particular type of terminal design.

The data sent to and from the computer must conform to a defined
format specification. Terminals are designed and built to satisfy
that requirement.

Software programs for microcomputers have been written to satisfy
that requirement such that the host computer system communicates
with the microcomputer as if it were a dumb terminal.

This process is called terminal emulation.

 "Generally speaking, microcomputers operate in one of two modes,
either text mode or graphics mode.

In text mode, also referred to as alphanumeric or character mode,
no graphical images can be displayed. The characters are taken
from the ASCII character set.

The IBM PC and compatible computers, can operate in either one
mode or the other. In the early to mid 1980's, most PCs were
operated in text mode. By the late 1980's, the hardware and
software had improved to the point that operating in a graphics
mode was acceptable.

As more and more applications are developed to operate in the
graphics mode, the text mode will become a thing of the past.
‹A computer of the third generation is classified as beginning in
the mid 1960's and continuing into the early 1970's, characterized
by physically smaller computers using integrated circuits on chips
for most of its circuitry, while utilizing disk storage and on-line

The third generation of computers started roughly in 1964 with the
advent of the IBM System/360 series.

P^TIFF is an acronym for Tagged Image File Format.

TIFF provides a way of storing and exchanging digital image data.
Aldus Corp., Microsoft Corp., and major scanner vendors developed
TIFF to help link scanned images with the popular desktop publishing

It is now used for many different types of software applications
ranging from medical imagery to fax modem data transfers, CAD
programs, and 3D graphic packages.

The current TIFF specification supports three main types of image
data: black and white data, halftones or dithered data, and
grayscale data.

ø?Time slicing is a scheduling method whereby a particular task is
given control of the microprocessor in a multitasking environment.

A program executes during its given time slice and is then swapped
out to await its turn to resume execution.
$XThe term token-passing is used to define an access scheme, which is
contention free, in a network of computers.

A token, or the right to broadcast signal, is passed through every
workstation on the network, whether it needs to transmit data or not.
This gives each station an equivalent share of the network time.

A workstation can only transmit a message when it has the token,
but the cable is always clear when the messages are ready to be

Token-ring and ARCnet technologies use a token-passing access

}Introduced by IBM in October of 1985, Token-ring refers to the wire
and the access protocol scheme whereby the workstations of a network
relay packets of data called a token around in a logical ring
configuration. When a station wants to transmit, it takes
possession of the token, transmits its data, then frees the token
after the data has made a complete circuit of the electrical ring.

This architecture is described completely in the IEEE 802.5 set of
standards, which defines the cabling, electrical and physical
topology, and access scheme of network products.

IBM's Token-ring system continues to support an increasing number of
mainframe computer Token-ring interfaces so that microcomputers can
share data on the mainframe networks. It connects microcomputers
via a special cable containing twisted wire pairs and transmits data
at four megabits per second.

ý>The term topology can refer to either the physical or the logical
configuration of a local area network (LAN).

Physical topologies, such as ring, star, and bus, are always
associated with the layout of the workstations and the cabling
that connects them.

The logical topology describes the way in which the flow of data
is regulated to and from the workstations on the network.

ARCnet, Ethernet, and Token-ring are the most common logical
topologies offered for today's local area networks.
YfThe components that make-up a microcomputer, such as the disk
drives, the power supply, the motherboard, and the various other
controller cards are most often housed in a cabinet that is
designed to rest in a horizontal position on a desktop or table

In order to conserve valuable desktop space, some microcomputers
are housed in a tower case that is designed to stand upright on
the floor.

Although the tower case is more practical, and often provides
more space for half-height drives, they are not as popular as
the conventional cases, and are consequently more expensive.

hA track is a storage channel on a disk, tape, or CD-ROM.

With magnetic devices, data bits are recorded in tracks as reversals
of polarity on the magnetic surface.

On floppy disks and hard disks, tracks are concentric circles of data.
Each track is a magnetic ring slightly wider than the read/write head
in the disk drive. A 360 K floppy disk has 40 tracks. Each track has
a number of sectors. Tracks are defined and recorded on a disk by the
operating system during a disk format operation.

With magnetic tapes, tracks are parallel lines. The track format is
determined by the specific tape drive, either 7-track or 9-track.

With CD-ROMs, data bits are recorded in tracks, not magnetically but as
physical pits underneath a clear, protective layer.
þA trackball is an input device for moving the cursor around on
a video display screen.

It consists of a mounting, usually a small desktop box, with a
ball inset. As the operator spins the ball with his fingers,
or the palm of his hand, the cursor on the screen moves at the
speed and in the direction of the ball's motion.

Trackballs are used in various graphics applications as well as
arcade games.

Unlike a mouse, a trackball doesn't run out of desk space or
need to be repositioned.

ïkThere are basically three methods for feeding paper into a printer.

A single sheet of paper can be fed into the printer in a manner
similar to a typewriter whereby the paper is pinched between the
platen and a roller.

Some printers, like the new laser printers, use sheet feeders, trays
filled with single sheets of paper which are fed into the printer as

Other printers use tractor feed mechanisms with a pair of pin-studded
belts or wheels that rotate in unison and pull the paper, which is
punched with holes along the margins, into the printer. Tractor feed
printers are fed boxes of continuous paper, fan-folded at the
perforations so that individual sheets can be separated after the
printing task is complete.

The TRON project is a standardization effort that aims to establish
a set of common data-interchange standards that will make it easy
for all computers to communicate in real time. TRON encompasses
all computers, including those found in household appliances, cars,
calculators, marine navigation, stereo systems, etc.

TRON is an acronym for The Real-Time Operating System Nucleus.

The name TRON applies to the development of a whole concept, not to
a specific product. TRON encompasses the development of an open
architecture, a family of VLSI chips, and system software. All
TRON specifications are available for adoption by anyone, free of
charge. This standardization is coordinated by the non-profit TRON
Association, in cooperation with the University of Tokyo.
2TSR is an acronym for Terminate and Stay Resident.

With microcomputers operating under DOS, only one program can be
executing at a time. Normally, when a program is terminated, the
memory is freed for the next program. But computer programs can be
designed and written to remain in memory until explicitly removed
or until the power is shut-off. These TSR programs, because they
remain in memory, can be re-activated by a pre-defined keystroke
sequence while another program is active.
Unfortunately, the use of TSRs often results in conflicts between
the programs. Some programs will not even load properly if a TSR
is resident in memory.

An example of a useful TSR is a program that provides an on-screen
calculator that can be activated while using a word processor or
a spreadsheet program.
ÍcTTL is an acronym for Transistor to Transistor Logic.

A TTL display is a monitor that accepts digital input at
standardized signal voltage levels.

Digital signals are also called TTL signals.

XTwinaxial cable, often abbreviated twinax, is similar to coaxial cable
but with two inner conductors instead of one. It is actually two
coaxial cables in a single insulated jacket.

Twinaxial cables are used with the IBM System 34/36/38 and AS400
communications environments.
7When two small insulated copper wires are wrapped or twisted around
each other to minimize interference from other wires in the cable,
the result is referred to as twisted pair wiring.

There are two types of twisted pair cables: unshielded and shielded.

Unshielded twisted pair wiring is commonly used in telephone cables
and provides little or no protection against interference.

Shielded twisted pair wiring is used in some networks for connecting
workstations but the signals must be boosted periodically.

Although it has limited bandwidths compared to coaxial cable or
optical fiber, inexpensive shielded twisted pair cabling is used by
AT&T in its StarLAN network and it can be used as an alternative to
coaxial cable for Ethernet networks.

ÑThe term two's complement refers to a number in the binary system
(base-2 system) that is the true complement of another number,
commonly used to represent negative numbers in computing.

The two's complement is a method for representing integers and is
defined in the IEEE-754-1985 specification.

A two's complement of an integer can be derived by reversing the
digits in a binary number (change 1's to 0's and 0's to 1's) and
adding one to the result.
6oA typeface is the design of a particular set of letters, symbols,
numbers, and punctuation marks.

For example, Helvetica, Times, Palatino, and Optima are typeface
families. Each family can have a number of different typefaces
such as Times Roman, Times Bold, Times Italic, which share the
same underlying characteristics, but require a separate design for
each weight or slant.

A font is a complete assortment of print characters for a single
typeface in a single size. For example, 12-point Helvetica is a
different font than 10-point Helvetica.


UART, Universal Asynchronous Receiver/Transmitter

USRT, Universal Synchronous Receiver/Transmitter

USART, Universal Synchronous Asynchronous Receiver/Transmitter

These are integrated circuits (chips) with serial/parallel conversion,
parallel/serial conversion, and other facilities designed for use
in synchronous and asynchronous serial communications.

These devices can take data directly from, or place it directly on
the data bus.

ÅnBoth of these terms refer to areas in random access memory above 640K
and below 1 MB on microcomputers using Intel 80386 CPUs and later.

The UMA, Upper Memory Area, refers to the expanse of memory between
640K and 1 MB and is normally reserved for hardware use. The ROM BIOS
is located in the UMA as well as the ROMs of various adapters in the
system such as the video card and the hard disk controller. Expanded
memory boards locate their page frames in the UMA.

The UMBs, Upper Memory Blocks, are pockets of usable RAM created in
unused areas of the UMA. The primary use for UMBs is to store TSRs
and device drivers above 640K therefore making more RAM available for
application programs.
|In 1987 work began on a new computer code called Unicode which
assigns a number to every printed character in use today. Joe
Becker of the Xerox Palo Alto Research Center coined the name
Unicode for "unique, universal, and uniform character encoding."

Unicode's fixed 16-bit (2-byte) code allows 65,536 characters
to accommodate all major living languages, including ideographs
used in Japan, China, Taiwan, and Korea; Cyrillic; Hebrew;
Arabic; Greek; Sanskrit; and many others. It also has math
and technical symbols, subscripts and superscripts, accent marks,
control codes, and code that mark the direction of the text.

ASCII, the code in use today, has always lacked the characters
to express the written words of most of the world's peoples.
Before the turn of the century, major computer companies will
actually implement Unicode in their systems and software.
0gUNIX is an operating system developed by AT&T at Bell Laboratories
by a team of programmers lead by Ken Thompson and Dennis M. Ritchie.

Since the UNIX operating system is easy to use, its design concept
had a great influence on other operating systems for microcomputers.
UNIX is widely used on a variety of computers, from mainframes to

micros. It is a powerful multitasking, multiuser system with many
high-level utility programs. Because of its superior capabilities
as a program development system, UNIX is expected to grow in

The Universal Product Code is a ten-digit computer readable bar
code used in labeling retail products. The code in the form of
vertical bars includes a 5-digit manufacturer identification
number and a 5-digit product code number.

Related information, such as pricing and inventory control, is then
stored in the computer so that when the product code is passed over
a scanner and read into the computer, product prices can be easily
transferred and inventory data accurately updated.

A sample of a Bar code:

+7A battery operated device that supplies a computer system with
electricity in the event of a power failure or an unacceptable
voltage level, is called an Uninterruptible Power Supply.

A true UPS system always supplies power through a battery even
when commercial power is available. There is no switching back
and forth between battery and commercial power. Sophisticated
UPS systems are tied to electrical generators that are designed
to provide electrical power for days.

Small UPS systems or stand-by power supplies switch to battery
backup power for a limited time so that the computer can be powered
down in an orderly manner. One of the key factors to consider
before purchasing a stand-by power supply system is the amount of
time required to switch to the battery backup power.

‘IWhen a new version of a computer or software system, such as a
language processor, produces identical results for a program
executed on the previous version, the new version is said to be
upward compatible.

New releases of software or upgrades to peripheral devices that
can do everything that the previous model could do, plus some
additional functions are said to be upward compatible.

"When a program is easy to understand by a wide variety of people,
the end users, not just the programmers, it is said to be user-

A user-friendly program is one that is not intimidating to those
who are unfamiliar with computers, or the program itself.

RAs a type of freely-distributed software, user-supported software
is copyrighted by the author and is thereby protected by U.S. and
international copyright law.

It may be freely copied and passed on to others, but each user is
expected to register with the author and pay a usage fee. The fee
may include some or all of the following: printed documentation,
the latest version of the program on disk, telephone support, free
updates, and commissions, but most importantly a legal license to
continue using the software.

User-supported software is distributed as Shareware.

¬|Unshielded Twisted Pair cabling is the wire that is often used
indoors to connect the telephones to outside service. It comes
with two or four wires twisted inside a flexible plastic sheath
or conduit. It utilizes modular plugs and phone jacks, which
makes it easy to relocate the phones, modems, workstations, or
other devices.

Unshielded Twisted Pair (UTP) is an excellent choice of cable for a
network installation because there are adapters for easy conversion
to all other types of cabling and because UTP is used for the
transmission of both voice and data.

ISO 8877, RJ-45 connectors are used with UTP.

UTP is also referred to as D-Inside Wire (DIW).

üSA Value Added Reseller is a company or organization whose products
result from the addition of some valuable feature to another
vendor's product, a very common practice worldwide.

VAR is also used as an abbreviation for Value Added Resource.

OThe Vertical Blanking Interval is the portion of the television
signal which carries no visual information and appears as a
horizontal black bar between the pictures when a TV set requires
vertical tuning.

The VBI is used for other applications, such as carrying close-
captioned signals for the hearing impaired. Digitized data can
also be inserted into the VBI for transmission at rates in excess
of 100,000 bits per second.
Information services such as stock market quotations and news
offerings are now available via the VBI of a cable television
signal. The data embedded in the VBI signal is retrieved from a
standard cable or satellite receiver wall outlet by a receiver set,
which connects to a RS-232 port on a microcomputer. Software
packages then allow subscribers instant access to the information,
which may be displayed in a number of user-definable formats.

âQVESA is an abbreviation for Video Electronics Standards Association.

Along with eight leading video board manufacturers, NEC Home
Electronics founded VESA in the late 1980's. The association's
main goal is to standardize the electrical, timing, and programming
issues surrounding 800 by 600 resolution video displays, commonly
known as Super VGA.

This standard provides guidelines for video board makers on how
best to achieve the resolution of 800 by 600 pixels.

&The VGA is an analog video controller. It handles color in much
the same way as a TV receiver. The VGA produces a signal that can
vary in small increments over a large spectrum of colors. The VGA
requires an analog color monitor.

Video Graphics Array refers to the display adapter built into
IBM's Personal System/2 Models 50, 60, 70, and 80. This adapter
can only be used with one of IBM's analog monitors.

The VGA provides a text mode with a 9-by-16 dot box for
characters, it emulates the EGA modes and the two new graphics
modes of MCGA, and it provides its own graphics mode with
16 colors and 640-by-480 pixel resolution.

For more information on video standards, ESCape from here, hit
Function Key F5 for Tables Menu and select Video Display Standards.

9sIn the past, many researchers and industry watchers have predicted
that one or another video display technology would finally dominate
and eliminate the competition. However this has not happened.
Video displays are used not only with computers, but with any device
that needs to display text or graphics like televisions, household
appliances, medical, and military equipment.

By far the oldest and most popular display device is the Cathode Ray
Tube (CRT), which first appeared in the early 1900's.

The other three major display technologies are the Liquid Crystal
Display (LCD), the gas-plasma display, and the electroluminescent
(EL) display.
Minor display technologies, comparatively, are the Vacuum Fluorescent
Display (VFD), electrophoretic displays, and the Light Emitting Diode
(LEDs) displays.
»gA virtual disk is an area of memory that has been defined for
temporary storage of programs and/or data. A device driver is used
to set-up and access the data in this area in a manner similar to a
hard disk but much faster.

A virtual disk is also referred to as a RAM disk or RAM drive
because it is created in Random Access Memory.

If your computer has extended memory (above 1 megabyte), or if it
has an extended memory board that meets EMS, you can use this area
for one or more virtual disks. Otherwise, a virtual disk can be
built in conventional memory.

When the system is re-booted, or when the power is turned off, the
information stored in virtual disks is lost.

¤When a program requires more space than is available in main
memory, a direct access storage device can be used to hold
program segments until needed in memory. The program utilizing
virtual storage appears to be held entirely in memory.

The virtual memory system allows a program to be broken up into
segments, called pages. Instead of bringing the entire program
into memory, it brings in as many pages that will fit and leaves
the remaining pages on disk.

When instructions are called for that are not in memory, the
appropriate disk page is read in, overlaying a page in memory.

The input and output of program pages is called paging or swapping.

/LVoice mail consists of messages spoken into a telephone, converted
to digital data, and stored in a computer system. The messages
can be stored either in RAM or on a hard disk for later retrieval.

Voice mail is a general term that includes both answering machine
and in-house voice mail systems. Sometimes referred to as phone
mail or voice processing systems, voice mail systems accept commands
from a touch-tone telephone.

In addition to the primary function of answering the telephone and
taking a message, PC-based voice mail systems can provide a variety
of other related features, such as providing dictation services,
auto-dialing for voice calls, voice synthesis, responding to alarm
signals by dialing an emergency number, and providing inbound and
outbound telemarketing services.

T9Computer memory, made up of dynamic RAM or static RAM chips, is
called volatile memory because its contents are lost when the power
is shut down.

Non-volatile memory, also called firmware, is capable of retaining
its contents without power.

Examples of non-volatile memory chips:

ROM's, PROM's, EPROM's, and EEPROM's

l3Most modern day computers, including microcomputers, minicomputers,
and mainframes are designed according to the 'Von Neuman architecture'.
The concept is named after Hungarian-born John Von Neumann (1903-1957),
an internationally renowned mathematician, who introduced the idea in
the 1940s.

The term 'Von Neuman architecture' refers to the sequential nature of
our modern day computers whereby instructions are stored and acted upon
one after the other. It refers to the conventional computer design,
composed of the five key components; a central arithmetic logic unit,
a memory connected by a bus to a central processing unit that performs
operations sequentially, and input and output devices.

Today, the operational slowdown caused by funneling information into
a single channel between the CPU and memory is referred to as the
Von Neuman bottleneck.
ØNVideo Random Access Memory chips are modified DRAM's on video
boards to allow them to transfer a large number of bits from the
memory array to a separate internal serial-shift register. After
making the transfer, the contents of the shift register are
independently shifted out to the video display.

The original VRAM was 64k-bit in size. It was followed by the
256K-bit device that combined the functionality of four 64K-bit
VRAM's on a single chip.

The latest VRAM generation is a 1-megabit device organized as
256K-by-4-bit with four 512-bit shift registers.

With the increasing resolutions of graphics displays and denser
memory devices, the VRAM is becoming indispensable to frame-buffer

€A wait state is a phase during the execution of a program in
which the processor must wait one or more clock cycles until
memory is able to respond to the processor's request.

A wait state is a pausing cycle in CPU operation that lets the
microprocessor synchronize with slower memory.

"Zero Wait State" - no waiting

If memory is slower than the processor, the system is said to
be bus bound. If the processor is slower than memory, the
system is processor bound.

The ideal memory system is one in which the rate that memory
can supply data to the processor matches the rate that the
processor can execute code.

þdWhen two or more computers are linked together for the purpose of
sharing information and/or peripheral devices, a network is created.

When the network is not confined to a geographically restricted area,
such as within the same building or perhaps on a college campus, it
is referred to as a Wide Area Network.

Typically, wide area networks serve to interconnect Local Area
Networks in different cities, states, and countries. A global
communications network of computers is referred to as a WAN.

WANs use several means of data transmission, including modems.
Dedicated digital transmission lines are popular for data that
must be transmitted quickly. Public data-transmission services,
such as packet switching networks are also widely used.
ÑjA computer's operating system is initiated with a boot procedure,
a start-up from scratch.

It is not always necessary to turn-off the power and then re-apply
it to start the boot procedure. If your IBM-compatible computer
hasn't locked-up, and the keyboard is active, the system can be warm
booted by depressing the following three keys simultaneously:


When your system is warm booted, the contents of memory are not
actually erased. The operating system is simply reloaded, and the
pointers to the beginning of available memory are reset. In fact,
a DOS program called DEBUG can be used to read from the part of
memory that was in use prior to the warm boot.
üQThe performance of a computer system is often evaluated by measuring
its operational speed in a variety of different tasks.

The Whetstone benchmark program, developed in 1976, was designed to
simulate arithmetic intensive programs used in scientific computing.
It is applicable in CAD and other engineering areas where floating-
point and trigonometric calculations are heavily used. The Whetstone
program remains completely CPU-bound and performs no I/O or system

The program was originally written in ALGOL, although the C and
Pascal versions became more popular by the late 1980's.

The speed at which a system performs floating point operations is
measured in units of Whetstones or floating point operations per
second (flops).

<With DOS and OS/2, there are two characters, * and ?, that can be
used when specifying one or more filenames in an operation. These
characters are called wildcards. A 'grep' search also uses wildcards.

For example, the DOS command DIR *.COM will cause a directory
listing of all the files that have the extension .COM to be displayed
on the screen. The asterisk (*) character can represent any valid
set of up to eight characters.

The question mark (?) can represent any single character in a
filename. For example, the DOS directory command, DIR SEPT??.DAT
would show directory information on the following filenames.

SEPT02.DAT (and any other files with names starting with SEPT,
SEPTEM.DAT followed by two characters, and a .DAT extension)
ŒjA Winchester disk is a hard disk storage device developed by IBM.

Winchester disks are characterized by their non-removable, sealed
platters; narrow tracks; and a lubricated surface on which the
read/write heads rest during start and stop operations. During
normal operation, the read/write heads float above the surface of
the platters on an air cushion.

The Winchester disk was originally designed with a dual 30 megabyte
capacity, and its 30-30 specification, the same as a Winchester
rifle, accounts for its name.

Although originally a self-contained, removable unit, the term is
often used to refer to any fixed hard disk.

s}The modern computer usage of the term "window" refers to a section,
frame, or partition of a larger entity.

With expanded memory on personal computers, windows are defined in
main memory for swapping data in and out.

When your video screen is divided into sections to display related
information or messages, each section is referred to as a window.
There are fundamentally two kinds of windowing schemes for the
display screen: "tiled windowing" and "overlapping windowing".
In a tiled windowing system, the multitasking operating system
does not allow the windows to overlap. Each active task is only
allocated a rectangular screen area in which to display messages.
In the overlapping scheme, the windows are like pieces of paper of
varying sizes laid on top of each other. The user can move the
windows about on the screen to see what was under them.

|^Microsoft Windows is a multitasking Graphical User Interface (GUI)
environment that runs on DOS-based microcomputers. It provides a
standard interface based on drop-down menus, screen windows, and a
pointing device such as a mouse.

In order for a program to be able to run in the Windows environment,
it must be specifically designed to take advantage of these features.
¨tWire wrap is a process whereby electrical connections can be
made without the need for soldering.

A specially designed tool wraps the wire tightly around a square
post. The sharp edges bite into the wire, producing a reliable

Large circuit boards containing thousands of connections can be
wire wrapped in a matter of seconds with programmable numerically-
controlled special purpose machines.

­WNIM is an acronym for Wide Area Network Interface Module. It is a
printed circuit board designed to provide up to four asynchronous
communication ports to a network of computers. The WNIM can reside
in a workstation or as an internal bridge in a file server.

Along with an asynchronous communications software package, WNIM
boards provide both incoming and outgoing telephone calls for LAN-
to-LAN data transfer.

ØA computer word is a storage unit of information, consisting of a
number of bits that comprise one storage location in main memory.

Large computers may have 32, 36, 48, or 64 bits in each word.

Often microcomputers, personal computers, will have 16-bit words.

When speaking of an IBM PC or compatible, 'word' can refer to
16 bits or 8 bits, depending on whether the point of reference is
the computer's 8-bit data bus or its 16-bit internal processing.

beOne of the most popular uses for personal computers is word
processing. It is an information processing system that relies
on automated and computerized typing, copying, filing, dictation,
and document storage and retrieval.

A word processor is a computer program designed to provide easy
manipulation of text. It can be used to write letters and/or
documents, while inserting, deleting, and/or changing words,
paragraphs, or pages.

Examples of popular word processors for microcomputers:

WordPerfect WordStar MultiMate PC-Write

Microsoft Word IBM DisplayWrite

ÚWWord wrap is a word processor feature.

While typing, if there isn't enough space for a word at the end
of a line, as the operator continues to type, the whole word is
moved to the beginning of the next line.

)$A worksheet is a data file created and processed by a spreadsheet

The popular spreadsheet program 1-2-3 from Lotus Development Corp.
uses the term worksheet to refer to the data file that is created,
edited, and saved during a session of data processing.

Many variations of the filename extension are in use today to help
identify these files. Some of the most popular are .WK1, .WK2,

For example, if you are using the spreadsheet program QUATTRO to
create a data file, the output filename may be MYDATA.WKQ.

²6A workstation is a terminal or a microcomputer from which an
operator can gain access to a network.

The nodes of a local area network are called workstations and
can be the diskless type or the high-performance stand-alone

Shortly after the introduction of microcomputers, the term
workstation mostly referred to the more powerful engineering
systems capable of state-of-the-art graphics for CAD/CAM.

µ$A worm is a nasty type of computer program designed to reproduce
itself over and over. Each new copy of the program creates another
copy. The purpose of a worm program is to cause a computer system
to crash by reducing the available disk storage space to zero.

A worm program is most often targeted for local area networks or
large multiprocessing systems. This type of destructive program
is not considered a software virus because it has no damaging effect
on other programs or data files.

Probably the most well-known worm program was activated on the large
Internet network on November 2, 1988. In two days, an estimated
6200 UNIX based computer systems were infected.
D&WORM is an acronym for Write Once Read Many, or Mostly.

It is an optical mass storage device capable of storing many
megabytes of information, but can be written to only once on any
given area of the disk.

A WORM disk typically holds more than 100 Megabytes of data.

Because a WORM drive cannot write over an old version of a file,
new copies of files are made and stored on other parts of the
disk whenever a file is revised. WORM disks are used to store
information that does not change often, such as system files,
compilers, and many application programs.
nHard disk drives for microcomputers are manufactured by numerous
companies resulting in a wide variety of designs, data access rates,
and storage capacities. But, generally speaking, hard disk drives
consist of at least three read/write heads for transferring data to
and from the magnetic surfaces, called platters.

Cylinders are imaginary vertical columns of tracks on the disk
platters. The tracks on the inside of the circular platters are
shorter in length than those closer to the edge.

The write precompensation number of a particular hard disk drive is
specified by the manufacturer. It is the cylinder number at which
the read/write heads increase the level of electrical current to
compensate for losses in the inner tracks of the platter. Flux
transitions are more widely spaced on the longer tracks at the
outside of the circular platter and need no additional compensation.
§'A write-protect feature prevents a disk or tape from being
written to thereby protecting any existing data.

With floppy diskettes, there is a write-protect notch in the
jacket that prevents writing to the diskette when the notch is
covered with a gummed tab or label.

On the 3.5" microdiskettes, the write-protect notch is a square
hole punched through the shell with a slug of plastic built into
the shell that can be slid over or away from the hole.

When the notch or hole is closed, new data can be written to the

With magnetic tapes, a plastic write-protect ring is inserted in
the back of the tape reel to prevent writing data to the tape.
:PAn acronym for What You See Is What You Get.

The term WYSIWYG, pronounced "wizzy-wig", is used as an adjective
to refer to computer programs such as word processors that generate
screen images that are identical in position and type appearance to
the final document, as opposed to those that show the formatting or
special type requested only when the document is printed.

The advantages are twofold: the planning of a visually pleasing
final document is easier and errors in the printed document can
be found quicker when the document is on the screen.
à;X.25 is a CCITT standard communications protocol used internationally
in packet switching networks, originally defined in 1976. It has been
revised and updated every four years since.
Rather than sending a stream of bits like a modem, an X.25 router
sends packets of data. There are varying packet sizes and types.
Each packet contains data to be transmitted as well as information
about the packet's origin, destination, size, and its place in the
order of the packets sent. There are clear packets which perform
the equivalent of hanging-up the phone. There are reset, restart,
and diagnostic packets. On the receiving end, the packet assembler/
disassembler (PAD) in the router translates the packets back into a
readable format.
Your credit is often verified at the check-out counter by a credit
card reader that dials an X.25 network port to send your credit
card number, store ID, and the purchase amount, assembled into
packets to the proper bank for verification.
X.400 is a term that refers to a series of OSI and CCITT standards
that describe the details of encoding electronic mail messages, both
textual and graphic, for transmission between unlike computers and

X.400 is actually a subset of the CCITT X.25 standard which governs
data communication on the packet switching networks.

Both of these important standards are maintained so that information
can be transmitted between all types of computers and a wide variety
of specialized terminal equipment from many manufacturers.
jsxBase is a generic term used to represent the various database products
on the market that are compatible with Ashton-Tate's dBase.

xBase is a product category.

The prime elements of xBase are the data model, the data file formats,
and the applications development language.

As Ashton-Tate's dBase, a data management system from the early 1980s,
became an industry standard and grew in popularity, competitors such
as Fox Software with FoxBASE and Nantucket with Clipper developed their
products to be similar. The file formats are the same. The languages
are referred to as being dBase compatible.
jXENIX is an operating system.

It is a variation of UNIX written by Microsoft Corp. for use on
IBM-compatible microcomputers. XENIX conforms to AT&T's System V
Interface Definition (SVID) with additional enhancements such as
file and record locking, graphics, and networking.
X)Introduced by IBM in September of 1990, the EXtended Graphics
Adapter is a 16-bit color video adapter with the capability of
operating at a resolution of 1024 by 768 in a non-interlaced mode.

The adapter offers support for 256 colors which results in 65,500
palettes at its 640 by 480 resolution. A 32,000 color display is
interpreted by the human eye as true color.

IBM hopes to establish XGA as an industry standard and has released
the technical details to third-party developers thereby guaranteeing
lower prices and wide availability.

See the Table "Video Display Standards"
OnXmodem is a file transfer protocol. It was the first file transfer
protocol to come into widespread use in the microcomputer world.

It was developed by veteran computer hacker Ward Christensen in the
mid-1970's to transfer files between machines running the CP/M
operating system. Until the late 1980's, because of its simplicity
and public domain status, Xmodem remained the most widely used
microcomputer file transfer protocol.

The file to be transmitted is divided into 128-byte blocks. Each
block is sent in sequence, together with a special starting character,
an identifying number, and a checksum. The checksum is a number
created by adding all of the bytes in the block together.

1K-Xmodem is an extension to Xmodem which increases the block size
from 128 to 1,024 bytes, thereby increasing transmission speeds.
=XMS, an abbreviation for Extended Memory Specification, is a software
interface developed by Lotus, Intel, Microsoft, and AST Research. It
defines a means of allowing real-mode applications to use extended
memory and certain areas of conventional memory not managed by DOS.

In order for the additional memory (RAM) to be utilized, an installable
memory manager or device driver must be loaded and the application
software must be designed to take advantage of it. A memory manager is
part of the operating system or can be purchased separately. The most
common are listed here.

EMM386.SYS by Digital Research, with DR DOS
HIMEM.SYS by Microsoft, with MS DOS
QEMM386.SYS by Quarterdeck Office Systems, purchased separately
386MAX.SYS by Qualitas, purchased separately
/Acronyms for transmission on/transmission off, these terms are used
to designate when the flow of data is stopped or started by a
computer or computer device. XON and XOFF characters are used to
control the flow of data between devices that operate at different

The XON and XOFF characters are part of the ASCII code where XON is
hex 11 and XOFF is hex 13. XON / XOFF is also known as DC1 / DC3.

Consider a parallel printer. It can send special flow control
characters to the computer as notification of status conditions.
When the printer is able to accept data it will send an XON character.
When it is unable to accept data, an XOFF character is sent. Other
special characters can also be sent to notify the CPU of conditions
such as paper-out or device off-line.
ÒpXOR is an abbreviation for the exclusive OR Boolean operator. It is
also sometimes abbreviated EOR.

The XOR Boolean operation yields true if and only if one of its
operands is true and the other is false. The XOR truth table is
shown below where 0 represents a false condition and 1 represents
a true condition.
³ a ³ b ³ a XOR b ³
³ 0 ³ 0 ³ 0 ³
³ 0 ³ 1 ³ 1 ³
³ 1 ³ 0 ³ 1 ³
³ 1 ³ 1 ³ 0 ³
JhAs a file transfer protocol, the Ymodem protocol was first released
as part of Chuck Forsberg's program YAM ("Yet Another Modem").
Ymodem is actually an extension to Xmodem, to overcome some of the
limitations of Xmodem.

Ymodem allows information pertaining to the transmitted file to be
sent along with the data, such as filename and length. Ymodem also
increases the size of the Xmodem block from 128 to 1,024 bytes and
adds the capability to transmit "batches" of files. In fact, Ymodem
is sometimes referred to as Xmodem-1K, and vice versa.

YmodemG is a streaming protocol built around the philosophy that no
news is good news. It sends the entire file before waiting for an
acknowledgment. If the receiving end detects an error in mid-stream,
it aborts the transfer. YmodemG is not an error correcting protocol.
õ*ZAP is a programming command that operates on a database file.

When the ZAP command is issued, all the records in the currently
opened database files are permanently deleted, erased. The structure
of the current file remains intact, only the records are removed. If
there are index files or an associated memo file, all records in
these files are also removed.

In a network environment, the current database file must be opened
in an exclusive mode before the ZAP command is issued.

Outside of a database programming environment, the term zap is often
used in place of the word delete. "The files were zapped yesterday."

A hardware device, such as a memory chip, can be damaged or zapped
by discharging static electricity through it.
úZero suppression is the replacement of leading zeros in a number
with blanks so that when the number appears, the leading zeros
are gone.

The data becomes more readable, for example, 000099 would be
displayed on the monitor or printed as 99.
OSA Local Area Network utilizing the communication ports of the
workstations (COM1, COM2, etc.) and RS-232 cabling is referred to
as a zero-slot or RS-232 LAN.

The term zero-slot derives from the fact that the LAN set-up does not
depend on network interface cards, which take up an expansion slot in
the PC workstation.

These type of LANs allow for the transfer of files several hundred
feet and to share expensive peripherals but will always perform
slower than LANs with network interface cards.

Examples of RS-232 LANs:

EasyLAN, LANlink, IDEAshare, ManyLink
b@A ZIP file is a type of compressed file created with a popular
program called PKZIP.EXE written by PKware, Inc.

In the microcomputer world, a ZIP file is one that has been
compressed, squashed, squeezed, crunched, and/or packed with a file
compression program in order to use less disk space and to reduce the
transfer time when sending files between computers.

Data Libraries store program and data files in compressed format and
rename the files using the ".ZIP" filename extension.

For further information write to:

PKware, Inc., 9025 N. Deerwood Drive, Brown Deer, WI 53223 USA

As a file transfer protocol, the Zmodem protocol was commissioned
by Telenet and placed in the public domain. Like Ymodem, it was
also designed by Chuck Forsberg and was developed as an extension
to Xmodem, to overcome some of the limitations of Xmodem.

Zmodem implements many of the features of the Kermit protocol, as
well as the capability to "step down" to the Xmodem or Ymodem
protocols on demand.

Among the key features of Zmodem are a 32-bit CRC offering a degree
of error detection 100,000 times greater than Xmodem CRC, a server
facility, batch transfers, and fast error recovery.

Zmodem was also specifically engineered to avoid sending certain
sequences, such as ESCape-carriage return-ESCape, that the Telenet
network uses to control the connection.
$$Zone recording is a technique for increasing the storage capacity
of magnetic disk drives.

Conventional disk drives record the same amount of data on each
track of the disk platter. However, the amount of surface area
close to the center of the circular platter may be many times
smaller than the areas at the outer edge of the platter. Thus
the density of the data at the center is the highest on the drive.

In theory, the same data density could be used on the entire
platter. Zone recording accomplishes that by placing more data
on each track as the heads move away from the center. The motor
speed remains constant while the speed of reading and writing data
is varied depending on the position of the heads. Near the edges
data is transferred at considerably greater rates.
¿QZulu time is a nickname for Greenwich Mean Time. Zulu time has
nothing to do with the Zulu people living in Natal, South Africa.

GMT, Greenwich Mean Time is the mean solar time of the meridian at a
metropolitan borough of London called Greenwich, England.

Greenwich Mean Time is used as the basis for standard time throughout
most of the world.

On the east coast of the United States, Eastern Standard Time is
GMT minus five hours.

  3 Responses to “Category : Tutorials + Patches
Archive   : PCGLOSRY.ZIP
Filename : GLOSRY.DBV

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: