EIA (Electronic Industries Alliance) an American organization that promotes industrial standards. On older computer equipment, “EIA” often marks an RS-232 or EIA-232D serial port. The EIA web site is at www.eia.org. EIA-232D the new official designation for the RS-232 standard for data communication. See RS-232. EICC (Electronic Industry Citizenship Coalition) a coalition of companies promoting socially responsible practices (web address: www.eicc.info). EIDE (Extended Integrated Device Electronics) a newer type of IDE disk drive and controller that allows a larger number of sectors per track and thereby overcomes the original limit of 528 megabytes per drive. EISA (Enhanced Industry-Standard Architecture) a standard 32-bit bus for IBM PC-compatible computers using the 386, 486, or Pentium micro- processor. EISA was developed by a group of competitors as an alterna- tive to IBM’s Micro Channel, retaining more compatibility with the original (ISA) bus. It has been largely superseded by PCI. In general, EISA computers can use ISA as well as EISA cards. The extra contacts on the EISA card edge connector are in a second row above the contacts that correspond to those on ISA cards. See ISA; BUS; PCI. eject 1. to remove a diskette or similar storage device from a computer. 2. to tell a computer that a diskette, CompactFlash card, or other storage device is about to be removed. The Eject operation tells the computer to finish writing data to the device immediately. The drive may or may not physically eject the storage device. electronic circuit diagram symbols graphical symbols used in schematic diagrams of electronic circuits. Examples are shown in Figure 92 on page 164. See also AND GATE; LOGIC CIRCUITS; NAND GATE; NOT GATE; OHM’S LAW; OR GATE; PARALLEL; SERIAL; TRANSISTOR. electronic commerce (EC) the carrying out of business transactions by computers. For example, computers at a store can monitor inventory lev- els and automatically order more merchandise when it is needed. Electronic commerce also includes transactions where there is a human participant, but the process is highly computerized, such as making pur- chases over the Internet. See also ELECTRONIC DATAINTERCHANGE; E-TAIL. Electronic Communications Privacy Act see ECPA. electronic data interchange (EDI) the transfer of information between organizations in machine-readable form in order to carry out business transactions. Electronic data interchange is becoming popular because it minimizes the errors that can occur if the same information has to be typed into computers several times. See OASIS. 163 electronic data interchange 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 163 FIGURE 92. Electronic circuit diagram symbols electronic document a document intended to be read as it is displayed on a monitor. An electronic document can use HYPERTEXT to create an inter- active environment for the reader. It can also use special effects such as animation, sounds, and music. Unlike with traditional printed docu- ments, there is no extra cost for full color. WEB PAGEs are a type of elec- tronic document; so are catalogs, documentation, and MULTIMEDIA presentations distributed on CD-ROM. electronic document 164 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 164 electronic mail (e-mail) the transmission of messages by computer from one person to another. Messages are saved until the recipient chooses to read them. E-mail is much more convenient than ordinary mail or tele- phone calls because it arrives immediately but does not require the recip- ient to be present, nor does it interrupt anything else the recipient may be doing. Messages are easily printed out, saved on disk, or forwarded to other people. All users of e-mail should be aware that backup copies of the messages can be saved and forwarded to others and that perfect privacy cannot be guaranteed. Contrast CHAT ROOM; INSTANT MESSAGING; NEWSGROUP. See also SPAM. For abbreviations commonly used in electronic mail, see AFAIK; BTW; FWIW; IANAL; IMHO; IRL; RYFM; TIA; YMMV. See also ELECTRONIC DATA INTERCHANGE; EMOTICON; FLAME; LOCAL- AREA NETWORK; WIDE-AREA NETWORK. electronic paper a display screen that has similar characteristics to ordi- nary paper. electronic publishing 1. the creation, manufacturing, and distribution of paperless documents. Examples of electronic documents are CD-ROM encyclopedias and web pages. Each of these new formats brings new challenges and technical problems, but all need the skill of someone who knows how to work with type and how to produce a pleasing combination of graphics and text. 2. the use of specialized computer-controlled equipment in the publish- ing and printing industries. Desktop publishing may be considered part of this trend, but electronic publishing encompasses the use of equip- ment not readily available to the mass market (powerful workstation class computers and digital presses, for example). Electronic publishing is superseding traditional methods of PREPRESS production. electrostatic printer a printer that operates by using an electric charge to deposit toner on paper. Laser printers are electrostatic printers. element one of the items in an ARRAY or LIST. elephant’s ear (slang) the symbol @; see AT SIGN. ELIZA a computer program developed by Joseph Weizenbaum of M.I.T. in 1966 to demonstrate that it is easy to make computers seem intelligent. ELIZA carries on a conversation with the user in the style of a psy- chotherapist, but it actually responds only to certain patterns of words in the input, ignoring the rest. For example, if the user mentions “mother,” ELIZA might reply, “Tell me more about your mother.” A version of ELIZA is built into the Emacs editor (Figure 93). To run it, press Esc X and type doctor and then press Enter. See EMACS. ELIZA passes the TURING TEST in a crude way, thereby demonstrating that human-like intelligence is easily faked. See also ARTIFICIAL INTELLIGENCE. 165 ELIZA 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 165 FIGURE 93. Eliza in action ellipsis typographic convention of using three dots (. . . ) to indicate the trailing off of a thought. In Windows, the ellipsis is typed by holding down Alt while keying 133 on the numeric keypad. Macintosh users can type an ellipsis by holding down Option and typing : (colon). Note that the three dots are actually one character. The spacing is different than simply typing three consecutive periods (Ellipsis . . . ; Three periods ). The ellipsis also has an important function in the menu system of Microsoft Windows. The appearance of ‘. . . ’ after a menu item means that a dialog box will appear when that command is selected. em dash a long dash (—). See DASH. EM64T see X64. Emacs (originally for “editor macros”) a TEXT EDITOR that originated as a set of MACROs written for another text editor by Richard M. Stallman in the 1970s. Today, Emacs is one of the most successful products of the GNU project (see GNU). It is distributed free of charge from www.gnu.org/ software/emacs in versions for numerous operating systems. Emacs is somewhat complex to use, but very powerful. It can edit files of any size, and they need not be text files, since non-text charac- ters are represented as octal codes. Emacs features an elaborate system of context-sensitive help. A Lisp-like programming language is built in so that users can define new editing operations. See also ELIZA. embedded font a FONT that is included within a file to ensure faithful repro- duction of the formatted document. embedded Linux any version of Linux that is used in an embedded system. embedded object an object included in your file that was created in another software package and that still maintains a LINK to the other soft- ware. If the object is changed in the original software, it will be updated in the second file. See OLE for more details. ellipsis 166 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 166 embedded system a computer that forms part of a larger machine of some other kind. The microprocessor that controls an automobile engine is an example. Embedded systems must usually be extremely reliable. They must also respond to events in real time (i.e., as they happen) without undue delay. See MICROCONTROLLER; REAL-TIME PROGRAMMING. EMC electromagnetic compatibility, the protection of equipment from electromagnetic interference. See RFI PROTECTION. emitter one of the three layers of a bipolar transistor. See TRANSISTOR. emoticon a typewritten symbol for a facial expression, often used in elec- tronic mail. For example, :) denotes a grin (look at it sideways), ;-) means “winking,” and =:-O means scared or surprised. Some emoticons are written so that they are viewed upright rather than sideways. ˆ-ˆ smile 0.0 surprise ˆ.ˆ; distress (with drops of sweat) emulation the process of achieving the same results as if you had a differ- ent machine than the one you’re actually using. For example, VT-100 emulation means making a computer act exactly like a VT-100 terminal. Emulation is different from simulation, which involves imitating the internal processes, not just the results, of the thing being simulated. emulsion the coated surface of photographic film. Normally, a photo- graphic negative looks right (not flipped) if the emulsion of the negative faces away from the person viewing it. Some graphics software offers output choices of “emulsion up” and “emulsion down” to produce flipped images for systems in which a photographic negative is going to be used backward. en dash a short dash (–). See DASH. Encapsulated PostScript (EPS) a file format that is widely supported by different computers, printers, and software. Most desktop publishing soft- ware supports the importation of Encapsulated PostScript files, thus pro- viding a common denominator for exchanging files. See also POSTSCRIPT. encoding a way of interpreting binary data as representing characters. The term is used particularly in the Microsoft .NET Framework, which sup- ports several formats of UNICODE and many national variations on ASCII. encryption the act of converting information into a code or cipher so that peo- ple will be unable to read it. A secret key or password is required to decrypt (decode) the information. More and more confidential data is being sent along computer networks, so it is becoming increasingly important to develop ways to send information over computer networks securely. For example, suppose we wish to send this message: HELLOGOODBYE 167 encryption 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 167 One way to encrypt it is to replace each letter with the letter that comes 10 places later in the alphabet, so that letter 1 (A) becomes letter 11 (K), letter 2 (B) becomes letter 12 (L), and so forth, starting over at A when we go past Z, like this: Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ Encrypted: KLMNOPQRSTUVWXYZABCDEFGHIJ Mathematically speaking, we change letter n to (n + 10) mod 26. Here mod stands for modulo and refers to the remainder after division by 26. For example, letter 20 (T) is shifted to 30, which becomes 30 mod 26 = 4, which is the letter D. Using this method, our message becomes: ROVVYQYYNLIO The recipients can easily decrypt the message as long as they know the algorithm (each letter is shifted by a certain number of places) and the key (in this case, 10). Unfortunately, this algorithm is so simple that it would be easy for a spy to crack the code. There are only 25 possible keys (a key of 26 would have no effect, and a key of 27 or higher would have the same effect as a lower one). It is easy to check all 25 possibilities: Trying key: 1 Message decodes as: QNUUXPXXMKHN Trying key: 2 Message decodes as: PMTTWOWWLJGM Trying key: 3 Message decodes as: OLSSVNVVKIFL Trying key: 4 Message decodes as: NKRRUMUUJHEK Trying key: 5 Message decodes as: MJQQTLTTIGDJ Trying key: 6 Message decodes as: LIPPSKSSHFCI Trying key: 7 Message decodes as: KHOORJRRGEBH Trying key: 8 Message decodes as: JGNNQIQQFDAG Trying key: 9 Message decodes as: IFMMPHPPECZF Trying key: 10 Message decodes as: HELLOGOODBYE In this case the spy can stop after the tenth try. To make the code harder to crack, we can use a longer key. For exam- ple, say that the first letter of the message will be shifted 10, the second will be shifted 8 letters, the third will be shifted 17, and so on. If you use a key with 8 numbers, then you can repeat the pattern after every 8 let- ters (i.e., the ninth letter will be shifted the same as the first letter, the tenth letter will be shifted the same as the second letter, and so on). The longer the key is, the harder it will be for the spy to try all possibilities. If you can design it so that the time required to check all possibilities exceeds the lifetime of the universe, you’re probably safe from this kind of attack. Even if you can design it so that the expense of cracking the code is greater than the benefit the spy would receive by cracking your code, you’re probably safe. However, there are other means of attack. Not all letters of the alpha- bet are used with equal frequency. A spy can program a computer to make a guess for the length of the key; collect all letters encrypted with a particular part of the key; and then check the frequency of encrypted encryption 168 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 168 letters, guessing that the most frequently appearing letter represents E, and so on. That guess may not be right, but guessing with this system will likely proceed much faster than guessing all the possibilities. This kind of attack is easier if the message is longer, but it won’t work for numerical data where the digits are equally likely to appear. Another likely means of attack would be to attack the key itself. If the spy gets hold of the key, it will be easy to decrypt all the messages. If a lot of people are sending messages to lots of other people, it is hard for them to deliver the keys to the recipients of the messages without letting them fall into the wrong hands. One way to solve this problem is with public key encryption. In this approach, each person has both a public key (which everyone knows) and a private key (which is kept secret). If Alice is sending a message to Bob, then the message will be encrypted using an algorithm that is based on Bob’s public key. Anyone can use this key to encrypt a message to Bob, but it can only be decrypted using Bob’s private key. Here is one example of how this can work, using the algorithm devel- oped by Whitfield Diffie and Martin Hellman in 1976. Alice and Bob agree on two numbers: n = 37 and g = 7. (In reality, n and g would be much larger than this.) Each of them has a private key, which we’ll call a and b, respectively. Alice and Bob generate their public keys A and B using the formula: Public key = g (private key) mod n Thus: Alice’s private key a = 8 Alice’s public key A = 7 8 mod 37 = 5,764,801 mod 37 = 16 Bob’s private key b = 6 Bob’s public key B = 7 6 mod 37 = 117,649 mod 37 = 26 Alice now generates another key K to use for the actual message using this formula: K = B a mod n = 26 8 mod 37 = 208,827,064,576 mod 37 = 10 This key is known as the session key. Now she can encrypt the message. For example, if she is sending the message HELLOGOODBYE, it will be encrypted as shown at the beginning of this entry. When Bob receives the message, he will calculate the session key using a very similar formula: 169 encryption 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 169 K = A b mod n = 16 6 mod 37 = 16, 777, 216 mod 37 = 10 Notice that this is the same value even though it is calculated from different numbers using a different formula. This works because of the following mathematical identities: (a × b) mod n = [(a mod n) × (b mod n)] mod n a c mod n = (a mod n) c mod n a bc = (a b ) c = (a c ) b a bc mod n = (a mod n) bc mod n = [(a mod n) b ] c mod n = [(a mod n) c ] b mod n a bc mod n = (a mod n) bc mod n = (a c mod n) b mod n a bc mod n = (a mod n) bc mod n = (a b mod n) c mod n To calculate the private key (equivalent to c), given the public key and the session key, you need to solve an equation of this general form: k = j x mod n If n happens to be a large prime number, it is very difficult to discover the value of x even if you know the values of k, j, and n. Thus, large prime numbers play a crucial role in public-key encryption. In practice, when computers are used for encryption, the calculations are usually car- ried out directly on the binary digits of the data, using a key given as a binary number. A longer key provides greater security, but the calcula- tion process becomes more complicated. All this presumes that you can get people’s public keys reliably so that you can be sure you’re really using Bob’s public key when you send messages to Bob. Since public keys are not secret, all you need is a trust- worthy database in which you can look up people’s public keys. Until 2000, the U.S. government regulated the export of strong encryption software in the same way that it regulates the export of weapons. This regulation dated from the 1940s, before general-purpose digital computers existed; encryption machines at that time were con- sidered to be military devices. See also AES; DES; DIGITAL SIGNATURE; HASH FUNCTION; ONE-WAY FUNC- TION; PGP; RSA ENCRYPTION; SSL. end 1. keyword that marks the end of a particular program structure in sev- eral programming languages. In BASIC, the END keyword tells the com- puter to stop executing the program. In Pascal, END marks the end of blocks of statements that start with BEGIN. end 170 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 170 2. the key on your keyboard that takes your cursor to the end of the cur- rent line. Some word processors use Ctrl-End as a keyboard shortcut to take you to the end of the document. end-of-file mark a symbol that indicates the end of a file. For example, in CP/M, all text files ended with ASCII character 26 (Ctrl-Z) because the computer did not otherwise keep track of the exact length of the file, only the number of disk sectors. In Windows, Ctrl-Z is often used the same way even though the computer knows exactly where the file ends whether or not an end-of-file mark is present. The UNIX end-of-file mark is Ctrl-D (ASCII 4). end user the person ultimately intended to use a product, as opposed to people involved in developing or marketing it. Energy Star a set of guidelines proposed by the U.S. Environmental Protection Agency in 1992 to reduce the amount of electricity consumed by personal computers. An Energy Star-compliant computer consumes less than 30 watts of power when idling (i.e., when turned on but not in use) and switches automatically into low-power mode if several minutes elapse without any keyboard activity. See GREEN PC. engine 1. the part of a computer program that implements a special technique; see INFERENCE ENGINE, MONTE CARLO ENGINE, SEARCH ENGINE. 2. the printing mechanism of a laser printer, not including the computer control circuitry. Many laser printers use an engine made by Canon in Japan. ENIAC (Electronic Numerical Integrator And Calculator) one of the first electronic computers, built at the University of Pennsylvania in the mid- 1940s. It contained about 18,000 vacuum tubes. Initially, the ENIAC was programmed by plugging cables into circuit boards. Today, one of the Internet nodes at the University of Pennsylvania is named eniac but is, of course, not the same machine. Enter key the key on a computer keyboard that you press at the end of each line in order to send the contents of that line into the computer. On most keyboards, the Enter key is the same as the Return key. However, IBM 3270-series terminals make a distinction: the Return key starts a new line, but the Enter key sends the contents of the whole screen to the computer. Under windowed operating systems, pressing the Enter key is usually equivalent to clicking on the currently selected icon or other highlighted item. enumerator a device driver or operating system component that identifies all hardware devices of a particular type. See BIOS ENUMERATOR. envelope 1. (in a draw program) the imaginary outline enclosing an object. You can edit the envelope, turning it from a rectangle into a curved shape, and thereby distorting everything inside it. 171 envelope 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 171 2. (in engineering) the limits imposed by physical or technical con- straints (called an “envelope” because they can be envisioned as sur- rounding an area on a graph). “Pushing the envelope” means working close to, or at, the limits. FIGURE 94. Envelope manipulation environment 1. the display and human interface provided by software. On a com- puter, an environment defines what you can do with the computer. For instance, the operating system, a word processor, and a spreadsheet pro- vide (at least) three different environments that respond to different com- mands. For example, if you type a word processing command while you are in the operating system environment, or vice versa, the command will not be understood. 2. (in Windows and UNIX) a data area in which you can store informa- tion for use by programs. To put information there, use the set com- mand; for example, under Windows, set prompt=$p$g tells the computer to display the current disk and directory (e.g., C:\MYDIR>) when it is ready for a command. To see the contents of the environment area, type set by itself. EPIC see IA-64. EPROM (Erasable Programmable Read-Only Memory) a type of memory chip that can be programmed electrically and erased by exposure to ultraviolet light. See also ROM; PROM; EEPROM. EPS see ENCAPSULATED POSTSCRIPT. Epson a prominent Japanese manufacturer of printers and other computer peripherals, distributed in the United States by Epson America, Inc., of Torrance, California. More information about Epson can be found at www.epson.com. The Epson MX-80 dot-matrix printer received wide acceptance dur- ing the early 1980s and set many standards to which other manufactur- ers subsequently adhered. Today, Epson makes high-quality color inkjet printers and other computer peripherals. equalize a paint program filter that adjusts the brightness range of a picture so that all levels of brightness become equally common. If some bright- environment 172 7_4105_DO_CompInternetTerms_E 12/29/08 10:23 AM Page 172 [...]... 2008, version 3 of Firefox set a world record for most number of downloads of a piece of software 7 _41 05_DO_CompInternetTerms_F 12/29/08 10: 24 AM firewall in a 24- hour period, and it continues to gain popularity See Page 192 192 BROWSER, MOZILLA firewall a link in a network that relays only data packets clearly intended and authorized to reach the other side Firewalls are helpful in keeping computers safe... to multiply n number of a’s together For example: 32 = 3 × 3 = 9 45 = 4 × 4 × 4 × 4 × 4 = 1,0 24 106 = 10 × 10 × 10 × 10 × 10 × 10 = 1,000,000 2 = a × a is called a to the second power, or a squared The numAlso, a ber that when multiplied by itself gives a is called the square root of a (written as a ) That means a × a = a For example, 9 = 3, since 3 × 3 = 9 7 _41 05_DO_CompInternetTerms_E 12/29/08 exponential... a way of breaching the security of a system or using features that should be inaccessible Often written and pronounced sploit 2 A piece of software designed to make it easy for a large number of would-be hackers to take advantage of such a software flaw Explorer the part of Windows that is used for exploring directories, files, and desktop menus To access it, right-click on the START BUTTON and choose... superseded by IDE and SCSI See IDE; SCSI ESRB Entertainment Software Rating Board (www.esrb.org) a non-profit, independent organization established in 19 94 that reviews entertainment software and web sites and assigns standardized ratings based on suitability for children, as well as descriptions indicating the amount of violent and/ or sexual content ERSB labels can be found on most commercial software titles... = 2 × 1 3! = 3 × 2 × 1 4! = 4 × 3 × 2 × 1 5! = 5 × 4 × 3 × 2 × 1 =2 =6 = 24 = 120 fade see TRANSITION EFFECT fair use in copyright law, a limited kind of use of copyrighted material that does not require the copyright holder’s permission For example, quoting a few sentences from a book and acknowledging the source is fair use 7 _41 05_DO_CompInternetTerms_F fanfic 12/29/08 10: 24 AM Page 186 186 The essential... as well as computerto -computer connections 7 _41 05_DO_CompInternetTerms_F 12/29/08 187 10: 24 AM Page 187 fiber optics FCC 1 (Federal Communications Commission) the agency of the U.S government that regulates all equipment that produces radio-frequency signals, including computers The FCC issues two levels of approval for computers: Class A (suitable for use in industrial or business areas) and Class... beginning and end of a command, so if you want them to appear on the screen, you have to type them as the escape codes < and >, respectively Escape key a key on a computer keyboard that has a special meaning depending on what software is being used In many programs and under Microsoft Windows, the Escape key means “get out of where you are now and get back to where you were before” (e.g., back out of. .. Sony trademark FireWire is most often used to interface video cameras to computers, but it has many other uses The original version (IEEE 13 94 and, with an improved software interface, 1394a) had a maximum speed of 40 0 megabits per second The newer version, IEEE 1394b, achieves 800 megabits per second or more See also BILINGUAL (definition 2) firmware software (i.e., computer programs) that is stored... released in 1985 by Microsoft for the Macintosh, and later adapted for Microsoft Windows exception a situation that prevents a computer program from running as specified, such as unexpectedly reaching the end of a file or trying to divide by zero See also TRY; UNHANDLED EXCEPTION Exchange Server popular Microsoft software for electronic mail and other collaboration Users run client software such as Outlook... sheet of paper and start a new one Compare LF (line feed) fiber optics cables that carry light rather than electrical energy Fiber-optic cables are made of thin fibers of glass Large amounts of data can be 7 _41 05_DO_CompInternetTerms_F 12/29/08 field 10: 24 AM Page 188 188 carried by a single fiber-optic cable Unlike wire cables, fiber-optic cables are not subject to crosstalk or electromagnetic noise, and . the exponent n in the expression a n means to multiply n number of a’s together. For example: 3 2 = 3 × 3 = 9 4 5 = 4 × 4 × 4 × 4 × 4 = 1,0 24 10 6 = 10 × 10 × 10 × 10 × 10 × 10 = 1,000,000 Also,. skill of someone who knows how to work with type and how to produce a pleasing combination of graphics and text. 2. the use of specialized computer- controlled equipment in the publish- ing and. of breaching the security of a system or using features that should be inaccessible. Often written and pronounced sploit. 2. A piece of software designed to make it easy for a large number of would-be