MICROSOFT Computer Dictionary, Fifth Edition

Microsoft Computer Dictionary, Fifth Edition

X-Y display

n. See vector display.

x-y matrix

n. An arrangement of rows and columns with a horizontal (x) axis and a vertical (y) axis.

x-y plotter

n. See plotter.

x-y-z coordinate system

n. A three-dimensional system of Cartesian coordinates that includes a third (z) axis running perpendicular to the horizontal (x) and vertical (y) axes. The x-y-z coordinate system is used in computer graphics for creating models with length, breadth, and depth. See the illustration. See also Cartesian coordinates.

x-y-z coordinate system.

Y: Y2K - YYYY

Y2K

n. See Year 2000 problem.

Y2K BIOS patch card

n. An ISA board that ensures that system calls to the BIOS return the correct year. The BIOS patch card checks the date the BIOS gets from the real-time clock and sends the correct date to whichever application or process requested it. While a BIOS patch card proved effective for most situations once the year 2000 was reached, some applications and processes that work directly with the real-time clock (not an advisable practice) actually received the wrong date on non-Year- 2000-compliant PCs.

Y2K BIOS test n. See BIOS test.

Y2K bug

n. See Year 2000 problem.

Y2K-compliant

adj. See Year 2000 compliant.

Y2K computer bug

Microsoft Computer Dictionary, Fifth Edition

n. See Year 2000 problem.

Y2K ready

adj. See Year 2000 compliant.

Yahoo!

n. The first major online Web-based directory and search engine for Internet resources, which can be found at http://www.yahoo.com. See also search engine (definition 2).

Yahoo! Mail

n. A popular Web-based e-mail service provided for free by Yahoo! Inc. Compare Hotmail.

Yahoo! Messenger

n. A popular instant-messaging application provided for free by Yahoo! Inc. on a variety of operating systems. See also instant messaging. Compare AIM, ICQ, .NET Messenger Service.

Yanoff list

n. The informal name of the Internet services list created and maintained by Scott Yanoff. The Yanoff list was one of the earliest directories of Internet services and resources. It is located at http://www.spectracom.com/islist/.

y-axis

n. The vertical reference line on a grid, chart, or graph that has horizontal and vertical dimensions. See also Cartesian coordinates.

YB

n. See yottabyte.

Year 2000 compliant

adj. The criteria for this varied among companies and organizations; however, a general theme was that software or hardware would make the transition from 1999 to 2000 without producing errors. For a PC, the general thinking was that if the real-time clock passed a Year 2000 BIOS test, it was Year 2000 compliant. However, testing the computing environment from end to end, considering the readiness of the operating systems, applications, custom code, data, and system interfaces, was also strongly recommended.

Year 2000 Information and Readiness Disclosure Act

n. A U.S. statute enacted in October 1998 that required U.S. companies to publicly disclose how they were attempting to make their systems or products ready for the year 2000. Many companies made this information available on the World Wide Web.

Year 2000 problem

n. Prior to January 1, 2000, a potential software problem stemming from the use of two digits (99) rather than four (1999) as year indicators in computer programs. Such programs assumed that 19 preceded every year value, and so could potentially fail or produce incorrect calculations by interpreting the year 2000 (00) as an earlier date than 19xx when the year rolled over into a new century. The use of two-digit year indicators was prevalent in, though not limited to, older programs that had been written when a saving of two bytes (digits) per year value was significant in terms of computer memory. Because the use of two-digit year indicators was widespread, companies, governments, and other organizations took measures on a large scale to prevent the Year 2000 problem from affecting their computing systems. In the end, however, the problem— luckily—proved largely uneventful.

Year 2000 ready

adj. See Year 2000 compliant.

Microsoft Computer Dictionary, Fifth Edition

Year 2000 rollover

n. The moment when the year in a computer system changed from 1999 to 2000. Also called: date rollover, millennium transition, rollover, Year 2000 transition.

Year 2000 time problem n. See Year 2000 problem.

Year 2000 transition

n. See Year 2000 rollover.

Yellow Pages

n. 1. The former name of a UNIX utility, provided by SunSoft (Sun Microsystems system software), that maintains a central database of names and locations of the resources on a network. The Yellow Pages enables processes on any node to locate resources by name. This utility is now known formally as NIS (Network Information Service). 2. InterNIC Registration Services’ database of domain names and their IP addresses. See also domain name, IP address. 3. Any of several Internet business directory services. Some are print publications, some are strictly electronic, and some are both.

Yes/No data type

n. A data type used to define database fields that will contain only one of two values, such as Yes or No and True or False. Null values are not allowed. See also boolean.

Yettie

n. Short for Young, Entrepreneurial Tech-based Twenty-something or Young, Entrepreneurial Technocrat. A person who works in a technology or Internet-related field and who embraces technological change and opportunity. Yettie is intended to be a successor to the older term “yuppie.”

YHBT

n. Acronym for you have been trolled. An expression used in e-mail and newsgroups to indicate that the receiver has taken a deliberately set bait. See also troll.

YHL

n. Acronym for you have lost. An expression used in e-mail and newsgroups, often following YHBT. See also YHBT.

Ymodem

n. A variation of the Xmodem file transfer protocol that includes the following enhancements: the ability to transfer information in 1-kilobyte (1024-byte) blocks, the ability to send multiple files (batch file transmission), cyclical redundancy checking (CRC), and the ability to abort transfer by transmitting two CAN (cancel) characters in a row. See also CRC, Xmodem.

yocto-

prefix A metric prefix meaning 10–24 (one septillionth in the U.S. system).

yoke

n. The part of a CRT (cathode-ray tube) that deflects the electron beam, causing it to strike a specific area on the screen. Also called: deflection coils. See also CRT.

yotta-

prefix A metric prefix meaning 1024 (one septillion in the U.S. system).

yottabyte

n. A unit of measure equal to 280 bytes, or approximately 1 septillion (1024) bytes. When calculated as a multiple of 1000 zettabytes (the next highest unit of measure), a yottabyte is

Microsoft Computer Dictionary, Fifth Edition

1,000,000,000,000,000,000,000,000 bytes; when calculated as 1024 zettabytes, a yottabyte is 1,208,925,819,614,629,174,706,176 bytes. The prefix yottais meant to sound like the Greek letter iota. Abbreviation: YB.

YY

n. The form in which the year part of a date is stored in some, mostly older, computer systems. Before 2000, the possibility existed that computers that used a 2-digit date would incorrectly interpret the year 2000 (year 00) as the year 1900 and disrupt the computer’s operation.

YYYY

n. Symbolic of providing fully distinguished dates, including 4-digit years. Using 4-digit years was an important step in many Year 2000 remediation programs—especially those focused on data.

Z: .z - ZV port

.z

n. The file extension identifying a UNIX file compressed using the gzip or compact utility. See also gzip.

.Z

n. The file extension for UNIX files that have been compressed using the compress utility. See also compress1.

Z39.50 standard

n. A specification for a query language based on SQL (structured query language). It is used by WAIS, among other Internet services, to search for files through the use of keywords and is widely used for remote access to library catalogs. See also structured query language, WAIS.

Z80

n. An 8-bit microprocessor from Zilog, a company founded by former Intel engineers. The Z80 has a 16-bit address bus, yielding a 64-kilobyte addressable memory space, and an 8-bit data bus. A descendant of the Intel 8080, it was the favored processor in the days of the CP/M operating system. One of the most popular computers of the early 1980s, the Radio Shack TRS80, was based on this chip. See also CP/M.

zap

vb. 1. To erase permanently. For example, to zap a file means to remove it without hope of retrieval. 2. To damage a device, usually by discharging static electricity through it.

z-axis

n. The third axis in a three-dimensional coordinate system, used in computer graphics to represent depth. See also Cartesian coordinates, x-y-z coordinate system.

ZB

n. See zettabyte.

zepto-

prefix A metric prefix meaning 10–21 (one sextillionth in the American system).

zero1

n. The arithmetic symbol (0) representing no magnitude.

zero2

vb. To fill or replace with zeros (for example, to zero a specified portion of memory, a field, or some other limited structure).

Microsoft Computer Dictionary, Fifth Edition

zero divide

n. A division operation in which the divisor is zero. Division by zero is mathematically undefined, is not allowed in a program, and is considered a bug.

zero flag

n. A flag (bit) in a microprocessor that is set (turned on), typically in a flag register, when the result of an operation is zero. See also flag (definition 1).

zero-insertion-force socket n. See ZIF socket.

zero-length string

n. A string that contains no characters. You can use a zero-length string to indicate that you know there’s no value for a field. You enter a zero-length string by typing two double quotation marks with no space between them ("").

zero out

vb. To set a variable value or a series of bits to zero.

zero suppression

n. The elimination of leading (nonsignificant) zeros in a number. For example, zero suppression would truncate 000123.456 to 123.456. See also significant digits.

zero wait state

n. The condition of random access memory (RAM) that is fast enough to respond to the processor without requiring wait states. See also wait state.

zetta-

prefix A metric prefix meaning 1021 (one sextillion in the American system).

zettabyte

n. A unit of measure equal to 270 bytes, or one sextillion (1021) bytes. When calculated as a multiple of 1000 exabytes (the next highest unit of measure), a zettabyte is 1,000,000,000,000,000,000,000 bytes; when calculated as 1024 exabytes, a zettabyte is 1,180,591,620,717,411,303,424 bytes. The prefix (zetta-) is meant to sound like the Greek letter zeta. Abbreviation: ZB.

z-fold paper

n. See fanfold paper.

ZIF socket

n. Short for zero-insertion-force socket. A kind of socket for integrated circuits that can be opened with a lever or screw, allowing the chip to be placed in the socket without the application of pressure. The lever or screw of the socket is then closed, causing the socket contacts to grip the chip’s pins. ZIF sockets facilitate frequent insertion and removal of chips, but they take up more space and are more expensive than conventional sockets.

zinc-air battery

n. Non rechargeable battery that is relatively inexpensive, offers extended battery life, and contains none of the harsh chemicals or metals found in conventional nickel metal cadmium (NiCad), nickel metal hydride (NiMH), or lithium ion (Li-ion) batteries.

.zip

n. A file extension that identifies a compressed archive file encoded in ZIP format, as by PKZIP. See also compressed file, PKZIP.

Microsoft Computer Dictionary, Fifth Edition

Zip drive

n. A disk drive developed by Iomega that uses 3.5-inch removable disks (Zip disks) capable of storing 100 megabytes of data. See the illustration. See also disk drive.

Zip drive.

Zmodem

n. An enhancement of the Xmodem file transfer protocol that handles larger data transfers with less error. Zmodem includes a feature called checkpoint restart, which resumes transmission at the point of interruption, rather than at the beginning, if the communications link is broken during data transfer. See also Xmodem.

zombie

n. A computer that has become the unwilling host of a DDoS (distributed denial of services) attack program and that is controlled by remote signals from the attacker. To create a zombie, a hacker utilizes security vulnerabilities to crack a Web, mail, news, or application server and plant hidden DDoS tools such as Trinoo and Tribal Flood Network. Later, at a signal from the attacker, the server becomes a zombie that will participate in a coordinated attack on other servers. See also DDoS, hacker.

zone

n. 1. On a LAN (local area network), a subgroup of users within a larger group of interconnected networks. 2. In Macintosh programming, a portion of memory that is allocated and reallocated by the memory manager facility as memory is requested and released by applications and by other parts of the operating system. See also heap (definition 1).

zone header

n. On the Apple Macintosh, a header at the beginning of a block of memory that contains information needed by the memory management facility in order to use that memory block effectively. See also header (definition 2).

zone transfer

n. The process whereby a secondary DNS server obtains information about a zone or domain from the primary server. See also zone (definition 1).

.zoo

Microsoft Computer Dictionary, Fifth Edition

n. The file extension that identifies compressed archive files created with the zoo file compression utility. See also zoo210.

zoo210

n. Version 2.1 of zoo, a program for creating compressed archive files (whose names have the extension .zoo). The algorithm for zoo210 is based on that of LHARC. Implementations of zoo210 are available for UNIX and Intel systems. See also archive file, LHARC.

zoom

vb. To enlarge a selected portion of a graphical image or document to fill a window or the screen. Zooming is a feature of many programs, including drawing, word processing, and spreadsheet programs, that allows the user to select a small part of the screen, zoom it, and make changes to the enlarged portion at a finer level of detail. See also window.

zoom box

n. A control in the upper right corner of the frame of a window on the Macintosh screen. When the user clicks on the zoom box, the window toggles between the maximum size and the size the user has set for it by dragging. See also window. Compare Maximize button.

zoomed video port n. See ZV port.

zoo virus

n. A virus that is kept in an isolated environment for the benefit of anti-virus research and training. Zoo viruses are not found outside the labs of anti-virus companies.

Zope

n. An open source application server for publishing objects on the Internet. Zope provides tools to integrate data and content from multiple sources into complete Web applications and can be used in conjunction with XML-RPC to form a system for remotely scriptable Web objects. Zope runs on UNIX, Windows NT and later, and most other major operating systems. See also XML-RPC.

z-order

n. 1. The order in which objects are drawn on top of one another onscreen to simulate depth (the third dimension) in conjunction with the x and y (height and width) coordinates. 2. The visual layering of windows or controls on a form along the z-axis (depth). The z-order determines which controls are in front of other controls. Each window or control has a unique position in the z-order.

Zulu time

n. Slang for Greenwich Mean Time.

ZV port

n. Short for zoomed video port. Port available on many portable computers as an inexpensive multimedia alternative to traditional video input. The ZV port allows data to flow uninterrupted from source to destination without need for buffering. Zoomed video was adopted by the Personal Computer Memory Card International Association (PCMCIA) to enable high transfer rates for portable computers, connected video cameras, and other multimedia devices.

Appendix A: Common Character Sets

Microsoft Computer Dictionary, Fifth Edition