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`Petitioners' EX1030 Page 1
`
`

`

`Dictionary of
`
`Computer and
`
`Internet Terms
`
`Sixth Edition
`
`§@
`
`BARRO ’S
`
`Petitioners‘ EX1030 Page 2
`
`Petitioners' EX1030 Page 2
`
`

`

`
`
`© Copyright 1998 by Barron’s Educational Series, Inc.
`Prior editions © copyright 1996, 1995, 1992, 1989, and 1986
`by Barron ’s Educational Series, Inc.
`
`All rights reserved.
`No part of this book may be reproduced in any form, by photostat, microfilm,
`xerography, or any other means, or incorporated into any information
`retrieval system, electronic or mechanical, without the written permission
`of the copyright owner.
`
`All inquiries should be addressed to:
`Barron’s Educational Series, Inc.
`250 Wireless Boulevard
`Hauppauge, New York 11788
`http://www.barronseduc.com
`
`Library ofC0ngres.v Catalog Card No. 98-6984
`International Standard Book No. 0-7641-0094-7
`
`Library of Congress Cataloging-in-Publication Data
`
`Downing, Douglas.
`Dictionary of computer and Internet terms / Douglas A. Downing,
`Michael A. Covington, Melody Mauldin Covington-—6th ed.
`p.
`cm.
`First-4th eds. published under title: Dictionary of computer
`ICITIIS.
`ISBN 0-7641-0094-7
`2. Internet (Computer network)—
`1. Computers—Dictionaries.
`Dictionaries.
`I. Covington, Michael A., 1957-
`.
`II. Covirigton,
`Melody Mauldin.
`111. Downing, Douglas. Dictionary of computer
`terms.
`IV. Title.
`QA76.15.D667
`1998
`0O4’.03—dc21
`
`PRINTED IN THE UNITED STATES OF AMERICA
`
`987654
`
`Petitioners‘ EX103O Page 3
`
`Petitioners' EX1030 Page 3
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`

`

`1
`
`
`
`CONTENTS
`
`About the Authors
`
`To the Reader
`
`Dictionary
`
`Characters and Symbols
`
`Petitioners‘ EX103O Page 4
`h
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`Petitioners' EX1030 Page 4
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`

`

`__:_
`
` FIGURE 14. “ARRANGE ICONS”
`
`arctan see ARC TANGENT.
`arc tangent the inverse of the trigonometric tangent function. If x =
`tany, then y = arctanx. In BASIC, the arc tangent function is called
`ATN. See TRIGONOMETRIC FUNCTIONS.
`arguments (actual parameters) values passed to a function or proce-
`dure by the calling program. See ACTUAL PARAMETER.
`ARPANET a computer network originally developed for the U.S.
`Defense Advanced Research Projects Agency (ARPA, now known
`as DARPA) to link research institutions. ARPANET introduced the
`TCP/IP protocols and eventually developed into the Internet. See
`INTERNET; WIDE AREA NETWORK‘, TCP/IP.
`arrange
`to place the icons on the screen in neat rows and columns,
`1.
`retrieving any that have been moved off the edge of the screen
`(Fig. 14).
`In Windows 95 and 98, “Arrange Icons” is on the menu that pops
`up when you right—click on an empty area of the desktop; it is also on
`the “View” menu of individual windows. In Windows 3.1, it is usually
`on a menu titled “Windows” or “View.”
`If you want the computer to keep the icons arranged automati-
`cally, tum on the “Auto arrange” feature; a check mark shows that it is
`selected. See also CASCADE; TILE.
`2.
`to place an item in relation to other items. In drawing pro-
`grams, there is usually an Arrange menu that contains commands
`(ALIGN, SEND TO FRONT, BACK ONE, etc.) relating to the placement
`of selected objects. Objects are layered as if they were opaque pieces
`of paper.
`array a collection of data items that are given a single name and
`distinguished by numbers (subscripts). For example, in BASIC, the
`declaration
`DIM X ( 5)
`creates an array of five elements that can be referred to as x(1), X(2),
`‘“F’é"ti‘tld?1‘éF§' EX103O Page 5
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`

`

`array
`
`I!
`
`X(1)
`X(2)
`X(3)
`X(4)
`X(5)
`FIGURE 15. ARRAY (ONE-DIMENSIONAL)
`
`You can store numbers in these elements with statements such as:
`
`x(1) = 10
`x(2) = 43
`X(3) = 8
`x(4) = 91
`X(5) = -5
`
`just as if each element were a separate variable. You can also use
`INPUT and READ statements on array elements just as if they were
`ordinary variables.
`Arrays are useful because they let you use arithmetic to decide
`which element to use at any particular moment. For example, you can
`find the total of the numbers in the five—element array It by executing
`the statements:
`TOTAL = 0
`FOR I = 1 T0 5
`TOTAL = TOTAL + X(I)
`NEXT I
`PRINT TOTAL
`
`Here TOTAL starts out as O and then gets each element of X added to it.
`Arrays can have more than one dimension. For example, the dec-
`laration DIM Y(3,5) creates a 3 X 5 array whose elements are:
`Y(1,1)
`Y(1,2)
`Y(1,3)
`Y(1,4)
`Y(1,5)
`Y(2,1)
`Y(2,2)
`Y(2,3)
`Y(2,4)
`Y(2,5)
`Y(3,1)
`Y(3,2)
`Y(3,3)
`Y(3,4)
`Y(3,5)
`
`
`
`
`
`E!
`fl
`
`
`
`FIGURE 16. ARRAY (TWO~D|MENS|ONAL, 3><5)
`
`
`
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`

`

`arrow keys
`_—?j—j
`
`Multidimensional arrays are useful for storing tables of data, such
`as three test grades for each of five students. See also DATA STRUC-
`TURES; SORT.
`
`arrow keys keys that move the cursor up, down, or to the left or right.
`The effect of these keys depends on the software being used. In a GUI
`environment, the arrow keys are basically an alternative to a mouse.
`Some drawing environments let you NUDGE the selected object with
`the arrow keys, giving you greater precision. Touch typists sometimes
`prefer the arrow keys to a mouse because it allows them to keep their
`hands on the keyboard. See NUDGE; KEYBOARD (diagram); MOUSE.
`Arrow keys do not have ASCII codes. Instead, each of them is read
`in a way that depends on the particular computer and software. Be
`cautious about using arrow keys when communicating with another
`computer; even if your cursor moves in the intended way, the other
`computer may not understand what you are doing, unless you are emu-
`lating a standard type of terminal (such as VT- 100) and have identified
`your terminal type to it.
`
`artificial intelligence (AI) the use of computers to simulate human
`thinking. Artificial intelligence is concerned with building computer
`programs that can solve problems creatively, rather than simply work-
`ing through the steps of a solution designed by the programmer.
`For example, consider computer game playing. Some games, such
`as tic—tac-toe, are so simple that the programmer can specify in
`advance a procedure that guarantees that the computer will play a per-
`fect game. With a game such as chess, however, no such procedure is
`known; the computer must instead use a heuristic, that is, a procedure
`for discovering and evaluating good moves.
`One possible heuristic for chess would be for the computer to iden-
`tify every possible move from a given position and then evaluate the
`moves by calculating, for each one, all the possible ways the game
`could proceed. Chess is so complicated that this would take an impos-
`sibly long time (millions of years with present—day computers).
`A better strategy would be to take shortcuts. Calculating only five
`or six moves into the future is sufficient to eliminate most of the possi-
`ble moves as not worth pursuing. The rest can be evaluated on the basis
`of general principles about board positions. In fact, an ideal heuristic
`chess—playing machine would be able to modify its own strategy on
`the basis of experience. Like a human chess player, it would realize
`that its opponent is also following a heuristic and would try to predict
`her behavior.
`One of the main problems of AI is how to represent knowledge in
`the computer in a form that can be used rather than merely reproduced.
`In fact, some workers define AI as the construction of computer pro-
`grams that utilize a knowledge base. A computer that gives the call
`number of a library book is not displaying artificial intelligence; it is
`merely echoing back what was put into it. Artificial intelligence would
`
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`27 ASCII
`
`come into play if the computer used its knowledge base to make gen-
`eralizations about the library’s holdings or construct bibliographies on
`selected subjects. (See EXPERT SYSTEM.)
`Computer vision and robotics are important areas of AI. Although
`it is easy to take the image from a TV camera and store it m a com-
`puter’s memory, it is hard to devise ways to make the computer recog-
`nize the objects it “sees.” Likewise, there are many unsolved problems
`associated with getting robots to move about in three—dimensional
`space—to walk, for instance, and to find and grasp objects—even
`though human beings do these things naturally.
`Another unsolved problem is natural
`language processing—
`getting computers to understand speech, or at least typewritten input,
`in a language such as English. In the late 1950s it was expected that
`computers would soon be programmed to accept natural—language
`input, translate Russian into English, and the like. But human lan-
`guages have proved to be more complex than was expected, and
`progress has been slow. The English speaking computers of Star Wars
`and 200] are still some years away. See NATURAL LANGUAGE PRO-
`CESSING.
`
`The important philosophical question remains: Do computers
`really think? Artificial intelligence theorist Alan Turing proposed a
`criterion that has since become known as the Turing test: A com-
`puter is manifesting human—like intelligence if a person communicat-
`ing with it by teletype, cannot distinguish it from a human being. Crit-
`ics have pointed out that it makes little sense to build a machine whose
`purpose is to deceive its makers. Increasing numbers of AI workers are
`taking the position that computers are not artificial minds, but merely
`tools to assist the human mind, and that this is true no matter how
`closely they can be made to imitate human behavior. See also ELIZA.
`
`ASC the function, in BASIC, that finds the ASCII code number asso-
`ciated with a given character. (See ASCII.) For example, ASC("A")
`is 65 because the ASCII code of the character A is 65 (expressed in
`decimal).
`
`
`1 S
`
`1
`
`1
`
`FIGURE 17. ASCENDERS
`
`ascender the part of a printed character that rises above the body of the
`letter. For instance, the letter d has an ascender and the letter 0 does
`not. See DESCENDER; TYPEFACE; X-HEIGHT.
`
`ASCII (American Standard Code for Information Interchange) a stan-
`dard code for representing characters as numbers that is used on
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`
`
`data compression 118
`
`3. Network layer. How does one machine establish a connection
`with the other? This covers such things as telephone dialing and
`the routing of packets. For examples, see HAYES COMPATIBIL-
`ITY (command chart); PACKET; x.25.
`
`4. Transport layer. How can the sender be sure the message has
`been received correctly? For examples, see XMODEM and KER-
`MIT.
`
`5. Session layer. How do theiinachines identify each other? How
`do users sign on and identify themselves?
`
`6. Presentation layer. What does the inforrnationiloolclike when
`received on the user’s machine?
`
`7. Application layer. How does the information fit into the system
`of software that will be used to process it?
`
`The OSI standard does not specify what any of these layers should
`look like; it merely defines a framework in terms of which future stan-
`dards can be expressed. In a simple system, some of the layers are
`handled manually or are trivially simple.
`data compression the storage of data in a way that makes it occupy
`less space than if it were stored in its original form. For example, long
`sequences of repeated characters can be replaced with short codes that
`mean “The following character is repeated 35 times,” or the like. A
`more thorough form of data compression involves using codes of dif-
`ferent lengths for different character sequences so that the most com-
`mon sequences take up less space.
`Most text files can be compressed to about half their normal size.
`Digitized images can often be compressed to 10 percent of their orig-
`inal size (or even more if some loss of fine detail can be tolerated),
`but machine—language programs sometimes cannot be compressed at
`all because they contain no recurrent patterns. See also ZIP FILE;
`STUFFIT; PCX; JPEG; MPEG.
`
`datagram a PACKET of information transmitted by NETWORK.
`data rate see BAUD.
`data set
`
`(in older telephone company nomenclature) a MODEM.
`1.
`(in OS/360 and related IBM operating systems) a file, referred
`2.
`to under the name by which it is known to the operating system. (The
`file is known to any particular program by another name, the “file-
`name,” specified by the JCL DD statement, TSO allocate command,
`or CMS filedef command.)
`data structures ways of arranging information in the memory of a
`computer. In computer programming, it is often necessary to store
`Petitioners‘ EX1030 Page 9
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`
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`119
`
`large numbers of items in such a manner as to reflect a relationshi
`between them. The three basic ways of doing this are the following:
`
`1. An array consists of many items of the same type, identified by
`number. The examination scores of a college class might be rep-
`resented as an array of numbers. A picture can be represented
`as a large array of brightness readings, one for each of the thou-
`sands of cells into which the picture is divided.
`
`2. A record consists of items of different types, stored together.
`For example, the teacher’s record of an individual student might
`consist of a name (character data), number of absences (an inte-
`ger), and a grade average (a floating—point number). Records
`and arrays can be combined. The teacher’s records of the entire
`class form an array of individual records; each record might
`contain, among other things, an array of test scores.
`
`3. A linked list is like an array except that the physical memory
`locations in which the items are stored are not necessarily con-
`secutive; instead, the location of the next item is stored along-
`side each item. This makes it possible to insert items in the mid-
`dle of the list without moving other items to make room. More
`complex linked structures, such as trees, can be constructed by
`storing more than one address with each item.
`
`See ARRAY; RECORD; LINKED LIST.
`
`data types ranges of possible values that a data item might have. Some
`possible data types include integers, real numbers, Boolean values,
`and character strings. Some languages, such as Pascal and Java, are
`very strict about requiring that the type of each variable be declared
`before it can be used, and an error message occurs if a program
`attempts to assign an inappropriate value to a variable. Other lan-
`guages make default assumptions about the types for variables if they
`are not declared (see FORTRAN.)
`The advantage of requiring data types to be declared is that it
`forces programmers to be more disciplined with their use of variables,
`and the computer can detect certain types of errors. There also can
`be disadvantages with a language requiring strict declaration of data
`types. For example, some operations (such as swapping the values of
`two variables) are essentially the same for any data type, so it should
`not be necessary to include separate subroutines for each type.
`Individual data items can be arranged into various types of struc-
`tures. See DATA STRUCTURES.
`
`daughterboard, daughtercard a small circuit board that plugs
`into a larger one. Contrast MOTHERBOARD.
`dB abbreviation for DECIBEL.
`
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`X
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`,_ ...- AAMAD $1415
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`/I/HI/II/III/I 0,
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`‘
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`1030»?-age 1 1
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`Petitioners' EX1030 Page 11
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