Barrons Publishing Dictionary of Computer and Internet Terms 10th

workgroup

1.a group of people who work together on a single project via a computer network.

2.a group of computers that are treated as a small unit of a larger network.

workstation a powerful microcomputer typically used for scientific and engineering calculations. Examples are the Sun Sparcstation and IBM RS/6000. Some newer PCs and Macintoshes fall into the category of workstations. See IBM PC; MACINTOSH; SUN WORKSTATIONS.

World Wide Web (WWW) a loosely organized set of computer sites that publish information that anyone can read via the Internet, mainly using HTTP (Hypertext Transfer Protocol). Each screenful (page) of information includes menu choices and highlighted words through which the user can call up further information, either from the same computer or by linking automatically to another computer anywhere in the world. Thus, the information is arranged in a web of tremendous size, and the links are created by the author of each page. See

HTML; INTERNET; INTERNET EXPLORER; MOSAIC; PROTOCOL.

World Wide Web Consortium (abbreviated W3C) a group of member organizations founded in 1994 that works to develop standards and otherwise enhance the World Wide Web. See web address www.w3.org.

WORM (write once, read many times) any storage medium that allows a computer to save information once, and then read that information, but not change it, such as a CD-R.

worm, worm virus a destructive computer program that spreads through the Internet or a LAN by transmitting itself to other computers from the infected one. For example, some worm viruses spread by e-mailing themselves to everyone in the victim’s ADDRESS BOOK.

WPA (Wi-Fi Protected Access), system for encrypting data on a wireless network that provides improvements over WEP because the encryption keys are changed regularly.

wrap

1.to manipulate the margins of text so that they follow the outline of a graphic. See Figure 303.

2.See WORD WRAP.

write to record digital information onto a disk or tape.

write-protect to set a disk or tape so that the computer will not write or erase the data on it.

To write-protect a 31⁄2-inch diskette, slide the movable tab so that the hole is uncovered.

WRT with respect to, with regard to.

.ws suffix indicating that an e-mail or web address is registered in Samoa (formerly known as Western Samoa), which has resold most of its domain addresses for use elsewhere, using the name “WorldSite.” See TLD.

FIGURE 303. Wrapping text around a graphic

WSDL (Web Services Description Language) an extension of XML describing how computers can work with WEB SERVICES.

WSVGA (Widescreen Super VGA) a monitor resolution of 1024 × 600 pixels.

WSXGA (Widescreen Super XGA) a monitor resolution of 1440 × 900 pixels.

WTB online abbreviation for “want to buy.”

WUXGA (Widescreen UXGA) a monitor resolution of 1900 × 1200 pixels.

WWW WORLD WIDE WEB.

WXGA (widescreen XGA) a monitor resolution of 1280 × 720 pixels or slightly more.

WYSIWYG acronym for “what you see is what you get.” With a word processing program, this means that the appearance of the screen is supposedly an exact picture of how the document will look when printed. A disadvantage is that subtle alignment errors may be hard to see, whereas in an editor with explicit codes, they would be obvious. See TEX; TYPESETTING MISTAKES.

X

x-axis the horizontal axis in an x-y coordinate system.

FIGURE 304. x-axis

x-height the height of the body of the lowercase letterforms (such as the small x of a typeface). Some typefaces make x half as high as X; some make it 40% as high; and some make it 60% as high.

A typeface with a large x-height looks larger than a typeface of the same point size with a small x-height. See also FONT; TYPEFACE.

FIGURE 305. x-height

X-OFF, X-ON codes that, respectively, turn off and on the transmission of data from a computer to a terminal. Many computers accessible by Telnet are programmed so that if the person at the terminal presses Ctrl-S (X-OFF), the computer will stop transmitting until the person presses Ctrl-Q (X-ON).

X server the process that manages the screen, keyboard, and mouse in the X Window System. See X WINDOW SYSTEM.

X terminal a terminal that is actually a small computer capable of running the X Window System. The terminal functions as an X server, managing the screen, keyboard, and mouse, while all other computation is done on the remote computer. See X WINDOW SYSTEM.

X Window System (“X Windows” for short) a software package for UNIX systems that allows programs to display text and graphics in windows and respond to a mouse (see WINDOW). X Windows software was developed at MlT and is distributed free. It is built into all major Linux distributions. Commercial extensions of it have been developed; an example is Open Windows, from Sun Microsystems.

X Windows relies on multitasking. A process called an X server manages the screen, keyboard, and mouse; other processes call on the X server when they want to use these devices.

X.25 an ITU-T (formerly CCITT) standard protocol that defines a standard way of arranging data in packets. Each packet contains information indicating which computer sent it and which computer should receive it. See

PACKET. X.25 has been adapted for amateur packet radio, and the adapted version is called AX.25. See also PROTOCOL.

X3D a graphics system for describing objects in space; intended as a successor to VRML. See www.web3d.org/x3d/specifications.

x64 a 64-bit extension of the Pentium (32-bit) CPU architecture originally developed by AMD for the Athlon 64 processor, and then adopted by Intel; the two companies’ versions, which are compatible but may differ slightly, are known as AMD64 and EM64T respectively. Unlike IA-64 (Itanium), x64 is completely compatible with unmodified Pentium software; programmers can take advantage of the additional 64-bit instructions if they wish. Thus, x64 extends the Pentium the same way the Pentium extended the earlier 80286.

x86 abbreviation for 8086/286/386/486, the series of microprocessors used in all PC-compatible computers, including the Pentium but not the PowerPC. See MICROPROCESSOR.

x86-64 earlier name for X64.

XA see CD-ROM XA.

Xanga a web site (www.xanga.com) with a web log service (see BLOG) that is especially popular with teenagers. “Xanga” is pronounced “zang-uh.”

Compare BLOGGER; LIVEJOURNAL; WORDPRESS.

XBRL (Extensible Business Reporting Language) a language for business financial data using XML-style tags. For more information, see www.xbrl.org.

xcopy a command in Windows and other operating systems for copying groups of files. It works just like copy except that as many files as possible are read into memory before any are written to disk. This is usually faster than using copy. Also, with the /s option, xcopy will copy a directory with all its subdirectories.

xDSL generic term for different types of DSL. See ADSL; DSL; HDSL; SDSL;

VDSL.

XGA (Extended Graphics Array) a super VGA card marketed by IBM for the PS/2. The original XGA, introduced in 1991, offered 1024 × 768pixel images. Today XGA denotes any monitor or projector that can display 1024 × 768-pixel images. See SVGA.

XHTML a newer formulation of HTML as an extension of XML. Documents written in XHTML can be processed as XML documents and can be viewed by XHTML-compliant browsers. See HTML; XML. See also www.w3.org/TR/xhtml1.

XMCL (Extensible Media Commerce Language) an XML-based language designed to support the business of delivering digital content (music,

etc.) over the Internet. Although much content on the Internet is free, other content will only be available if there is a mechanism allowing the content creators to receive reasonable payment for their work. XMCL provides a standard way to transmit data needed for this process. For more information, see www.xmcl.org.

XML (Extensible Markup Language) a language similar to HTML, but designed for transmitting complex data structures of any type, not just web pages. XML is a subset of SGML adopted as a standard by the W3C in 1998. XML is designed to be easier to use than SGML while providing richer features and better implementation of than HTML.

In an XML document, the beginning and end of elements of the document are marked with tags, such as <from> and </from> to mark the beginning and end of the part of a memo that indicates who the memo is from. Note that the notation for tags follows the same format as HTML. However, XML does not define a set of tags as does HTML. Instead, it is extensible because different users can extend the language definition with their own set of tags.

When an XML document uses these tags, a document type definition (DTD) is needed to define the elements. The DTD may be included in the XML document itself, or it may be in a separate document that can be used by all documents in the same document class.

Below is an example of an XML document that we could use to store data about people we might want to recruit for computer jobs in our company. In this example, the document type definition (DTD) is included at the front of the document.

This example creates a document type called RECRUITLIST, which consists of elements called RECRUITS. Because the DTD contains a plus sign after the declaration of RECRUIT, a document can have one or more recruits. Each RECRUIT can consist of four elements: NAME, ADDRESS, DEGREE, and ACCOMPLISHMENT. Each recruit must have exactly one NAME and one ADDRESS. The asterisk after DEGREE means that a recruit can have zero, one, or more degrees. The element NAME consists of three elements: FIRSTNAME, LASTNAME, and NICKNAME. The question mark after the definition of NICKNAME means that a name may contain zero or one nickname. Following the document type definition, this sample shows two particular recruits.

<?xml version=”1.0” encoding=”UTF-8”?>

If we run this document through an XML-validating parser, we can verify that it is a valid XML document. A valid XML document must contain a closing tag for each opening tag, the elements must be correctly nested inside each other, and all of the elements specified in the DTD must be present in the specified sequence. However, the XML parser will not process the data; that must be done with an application designed to work with this type of document. XML is intended for a broad array of applications, including presentation of web documents and storage and transfer of database information. For more information, see www.w3.org/XML.

XOR gate (exclusive-OR gate) a logic gate whose output is 1 when one but not both of its inputs is 1, as shown in this table.

The XOR function is interesting because if you XOR one bit pattern with another, you get an obscure pattern; but if you then XOR that pattern with one of the original patterns, you get the other original pattern. See

Figure 306. See also COMPUTER ARCHITECTURE; LOGIC CIRCUITS.

FIGURE 306. XOR gate (logic symbol)

XP

1.version 5.1 of Microsoft Windows. See WINDOWS, MICROSOFT.

2.abbreviation for EXTREME PROGRAMMING.

XrML (Extensible Rights Markup Language) an XML-based language for specifying rights and conditions associated with digital content or services. For more information, see www.xrml.org. See also COPYRIGHT.

XT the second model of IBM PC, introduced in 1983. The PC XT had eight expansion slots instead of the original five and it included a 10megabyte hard disk. The microprocessor was a 4.77-MHz 8088 with an 8-bit bus, just as in the original PC.

XUL (pronounced “zool”) Extensible User-interface Language, an XMLbased language for defining graphical user interface elements such as buttons and dialog boxes. For more information, see the web site at developer.mozilla.org/en/docs/XUL.

Y

Y online abbreviation for “why?”

y-axis the vertical axis in an x-y coordinate system (Figure 307).

FIGURE 307. y-axis

Y2K abbreviation for “year 2000.” (K stands for “thousand.”) See YEAR

2000 PROBLEM.

Y2K compliant unaffected by the YEAR 2000 PROBLEM. Technically, to be Y2K compliant, a piece of software must never print the year as two digits. In practice, however, no problem is caused by printing 2000 as 00 so long as calculations involving the date come out correctly.

Yahoo a popular SEARCH ENGINE for the WORLD WIDE WEB, accessible at www.yahoo.com. Yahoo also offers other Internet services. Compare

GOOGLE.

Year 2000 Problem (Y2K Problem) the problem caused by software that represents the year date as two digits (such as 99 for 1999) and thus does not recognize that 2000 comes after 1999. Instead, the software interprets 00 as 1900. This causes mistakes in calculations that involve the date.

Dates were originally represented as two digits for two reasons. First, in the 1960s, computer memories were very expensive, and even the largest computers’ total memory was far smaller than that of a modern PC. Second, data was stored on punched cards, each of which could hold only 80 characters; the two characters saved by omitting “19” could be used for something else.

Some banks dealt with the Year 2000 Problem as early as 1970 when issuing 30-year loans. In 1998 and 1999, computer users were urged to update all software, and there was widespread panic as news media reported that all types of machinery, even microprocessor-controlled car engines and coffee makers, would fail on January 1, 2000. These predictions proved false; problems occurred in only out-of-date accounting software and the like. Nonetheless, much of the updating was necessary or beneficial for other reasons.

Yellow Book the book that originally defined the Philips/Sony standard for recording data on CD-ROMs.

YKYBHTLW abbreviation for “you know you’ve been hacking too long when,” as in “YKYBHTLW you start to dream in C++.” In this expression, hacking means “programming,” not “attempting computer crime.”

See HACKER.

YMMV online abbreviation for “your mileage may vary” (i.e., your results may be different).

yotta- metric prefix meaning ×1,000,000,000,000,000,000,000,000 (1024). Yotta is apparently a nonsense word. See METRIC PREFIXES.

YouTube a popular video sharing site where users can upload and watch video clips of all types. Since 2006, YouTube has been owned and maintained by Google. Although many videos are homemade, be aware of copyright issues before posting television or movie clips or music videos. See COPYRIGHT.

“You’ve Got Mail” the familiar audio announcement used by AMERICA ONLINE software to announce the arrival of e-mail. It is derived from “you have mail,” a text message often displayed to users logging into UNIX.

Z

z-axis the direction toward and away from the viewer in a three-dimen- sional coordinate system. Compare X-AXIS; Y -AXIS.

FIGURE 308. z-axis

In computer graphics, the x-axis is always horizontal and the y-axis is always vertical; the z-axis points toward the viewer. In mathematics books, however, the axes are often drawn as if the paper were lying on a flat desk with the z-axis pointing toward the ceiling; thus, in printed diagrams the z-axis often points straight up.

z-buffer (3D program) an editing buffer that allows the program to keep track of objects that are hidden from view by other objects.

z-order the arrangement of elements of an image from front to back. Z-order determines which items are in front of others.

Z80 an 8-bit microprocessor produced by Zilog, Inc., and used in microcomputers that ran the CP/M operating system in the early 1980s. See

MICROPROCESSOR.

zero day flaw a software vulnerability that has been exploited by malicious hackers on or before the day the software creators become aware of the problem.

zetta- metric prefix meaning ×1,000,000,000,000,000,000,000 (1021). Zetta is apparently a nonsense word. See METRIC PREFIXES.

ZIF socket (zero insertion force socket) a socket into which an integrated circuit can be inserted without pressure. It has a lever to open up the holes for easy insertion. The lever is then moved to tighten the connectors once the IC is in place.

Zip drive a 100, 250, or 750-megabyte removable-cartridge disk drive made by Iomega Corporation of Roy, Utah.

ZIP file a file containing files and/or directories compressed with WinZip (web address: www.winzip.com), an earlier program called PKZIP, or the