i486DX

n. An Intel microprocessor introduced in 1989. In addition to the features of the 80386 (32-bit registers, 32-bit data bus, and 32-bit addressing), the i486DX has a built-in cache controller, a built-in floating-point coprocessor, provisions for multiprocessing, and a pipelined execution scheme. Also called 486, 80486. See also pipelining (definition 1).

i486DX2

n. An Intel microprocessor introduced in 1992 as an upgrade to certain i486DX processors. The i486DX2 processes data and instructions at twice the system clock frequency. The increased operating speed leads to the generation of much more heat than in an i486DX, so a heat sink is often installed on the chip. Also called 486DX, 80486. See also heat sink, i486DX, microprocessor. Compare OverDrive.

i486SL

n. A low-power-consumption version of Intel's i486DX microprocessor designed primarily for laptop computers. The i486SL operates at a voltage of 3.3 volts rather than 5 volts, can shadow memory, and has a System Management Mode (SMM) in which the microprocessor can slow or halt some system components when the system is not performing CPU-intensive tasks, thus prolonging battery life. See also i486DX, shadow memory.

i486SX

n. An Intel microprocessor introduced in 1991 as a lower-cost alternative to the i486DX. It runs at slower clock speeds and has no floating-point processor. Also called 486, 80486. See also 80386DX, 80386SX. Compare i486DX.

IAB

See Internet Architecture Board.

I-beam

n. A mouse cursor used by many applications, such as word processors, when in text-editing mode. The I-beam cursor indicates sections of the document where text can be inserted, deleted, changed, or moved. The cursor is named for its I shape. Also called I-beam pointer. See also cursor (definition 3), mouse.

IBM AT

n. A class of personal computers introduced in 1984 and conforming to IBM's PC/AT (Advanced Technology) specification. The first AT was based on the Intel 80286 processor and dramatically outperformed its predecessor, the XT, in speed. See also 80286.

IBM PC

n. Short for IBM Personal Computer. A class of personal computers introduced in 1981 and conforming to IBM's PC specification. The first PC was based on the Intel 8088 processor. For a number of years, the IBM PC was the de facto standard in the computing industry for PCs, and clones, or PCs that conformed to the IBM specification, have been called PC-compatible. See also PC-compatible.

ICMP

n. Acronym for Internet Control Message Protocol. A network-layer (ISO/OSI level 3) Internet protocol that provides error correction and other information relevant to IP packet processing. For example, it can let the IP software on one machine inform another machine about an unreachable destination. See also communications protocol, IP, ISO/OSI model, packet (definition 1).

icon

n. A small image displayed on the screen to represent an object that can be manipulated by the user. By serving as visual mnemonics and allowing the user to control certain computer actions without having to remember commands or type them at the keyboard, icons are a significant factor in the user-friendliness of graphical user interfaces. See also graphical user interface.

iconic interface

n. A user interface that is based on icons rather than on typed commands. See also graphical user interface, icon.

IDE

n. Acronym for Integrated Device Electronics. A type of disk-drive interface in which the controller electronics reside on the drive itself, eliminating the need for a separate adapter card. The IDE interface is compatible with the controller used by IBM in the PC/AT computer but offers advantages such as look-ahead caching. See integrated development environment.

idle

adj. 1. Operational but not in use. 2. Waiting for a command.

IE

n. Acronym for information engineering. A methodology for developing and maintaining information-processing systems, including computer systems and networks, within an organization. See Internet Explorer.

IEEE

n. Acronym for Institute of Electrical and Electronics Engineers. An organization of engineering and electronics professionals notable for developing standards for hardware and software.

IEEE 488

n. The electrical definition of the General-Purpose Interface Bus (GPIB), specifying the data and control lines and the voltage and current levels for the bus. See also General-Purpose Interface Bus.

IEEE 696/S-100

n. The electrical definition of the S-100 bus, used in early personal computer systems that used microprocessors such as the 8080, Z-80, and 6800. The S-100 bus, based on the architecture of the Altair 8800, was extremely popular with early computer enthusiasts because it permitted a wide range of expansion boards. See also Altair 8800, S-100 bus.

IEEE 802 standards

n. A set of standards developed by the IEEE to define methods of access and control on local area networks. The IEEE 802 standards correspond to the physical and data-link layers of the ISO Open Systems Interconnection model, but they divide the data-link layer into two sublayers. The logical link control (LLC) sublayer applies to all IEEE 802 standards and covers station-to-station connections, generation of message frames, and error control. The media access control (MAC) sublayer, dealing with network access and collision detection, differs from one IEEE 802 standard to another: IEEE 802.3 is used for bus networks that use CSMA/CD, both broadband and baseband, and the baseband version is based on the Ethernet standard. IEEE 802.4 is used for bus networks that use token passing, and IEEE 802.5 is used for ring networks that use token passing (token ring networks). In addition, IEEE 802.6 is an emerging standard for metropolitan area networks, which transmit data, voice, and video over distances of more than five kilometers. See also bus network, ISO/OSI model, ring network, token passing, token ring network.

IETF

n. Acronym for Internet Engineering Task Force. The organization that is charged with studying technical problems facing the Internet and proposing solutions to the IAB. The IETF is managed by the IESG. See also Internet Engineering Steering Group.

IFF

n. Acronym for Interchange File Format. See .iff.

IGES

n. See Initial Graphics Exchange Specification.

IIS

See Internet Information Server.

illegal

adj. Not allowed, or leading to invalid results. For example, an illegal character in a word processing program would be one that the program cannot recognize; an illegal operation might be impossible for a program or system because of built-in constraints. Compare invalid.

image

n. 1. A stored description of a graphic picture, either as a set of brightness and color values of pixels or as a set of instructions for reproducing the picture. See also bit map, pixel map. 2. A duplicate, copy, or representation of all or part of a hard or floppy disk, a section of memory or hard drive, a file, a program, or data. For example, a RAM disk can hold an image of all or part of a disk in main memory; a virtual RAM program can create an image of some portion of the computer's main memory on disk. See also RAM disk.

image color matching

n. The process of image output correction to match the same colors as were scanned or input.

image editor

n. An application program that allows users to modify the appearance of a bitmapped image, such as scanned photos, by using filters and other functions. Creation of new images is generally accomplished in a paint or drawing program. See also bitmapped graphics, filter (definition 4), paint program.

image map

n. An image that contains more than one hyperlink on a Web page. Clicking on different parts of the image links the user to other resources on another part of the Web page, a different Web page, or a file. Often an image map, which can be a photograph, drawing, or a composite of several different drawings or photographs, is used as a map to the resources found on a particular Web site. Image maps are created with CGI scripts. Also called clickable maps. See also CGI script, hyperlink, Web page.

imaging

n. The processes involved in the capture, storage, display, and printing of graphical images.

IMAP4

n. Acronym for Internet Message Access Protocol 4. The latest version of IMAP, a method for an e-mail program to gain access to e-mail and bulletin-board messages stored on a mail server. Unlike POP, IMAP allows a user to retrieve messages efficiently from more than one computer. See also POP3, Post Office Protocol.

IMHO

Acronym for in my humble opinion. IMHO, used in e-mail and in online forums, flags a statement that the writer wants to present as a personal opinion rather than as a statement of fact.

IMO

Acronym for in my opinion. A shorthand phrase used often in e-mail and Internet news and discussion groups to indicate an author's admission that a statement he or she has just made is not strictly a fact.

inactive window

n. In an environment capable of displaying multiple on-screen windows, any window other than the one currently being used for work. An inactive window can be partially or entirely hidden behind another window, and it remains inactive until the user selects it. Compare active window.

in-band signaling

n. Transmission within the voice or data-handling frequencies of a communication channel.

Inbox

n. In many e-mail applications, the default mailbox where the program stores incoming messages. See also e-mail, mailbox. Compare Outbox.

indent¹

n. 1. Displacement of the left or right edge of a block of text in relation to the margin or to other blocks of text. 2. Displacement of the beginning of the first line of a paragraph relative to the other lines in the paragraph. Compare hanging indent.

indent²

vb. To displace the left or right edge of a text item, such as a block or a line, relative to the margin or to another text item.

index¹

n. 1. A listing of keywords and associated data that point to the location of more comprehensive information, such as files and records on a disk or record keys in a database. 2. In programming, a scalar value that allows direct access into a multi-element data structure such as an array without the need for a sequential search through the collection of elements. See also array, element (definition 1), hash, list.

index²

vb. 1. In data storage and retrieval, to create and use a list or table that contains reference information pointing to stored data. 2. In a database, to find data by using keys such as words or field names to locate records. 3. In indexed file storage, to find files stored on disk by using an index of file locations (addresses). 4. In programming and information processing, to locate information stored in a table by adding an offset amount, called the index, to the base address of the table.

indexed search

n. A search for an item of data that uses an index to reduce the amount of time required.

INET

n. 1. Short for Internet. 2. An annual conference held by the Internet Society.

infobahn

n. The Internet. Infobahn is a mixture of the terms information and Autobahn, a German highway known for the high speeds at which drivers can legally travel. Also called Information Highway, Information Superhighway, Net.

information

n. The meaning of data as it is intended to be interpreted by people. Data consists of facts, which become information when they are seen in context and convey meaning to people. Computers process data without any understanding of what the data represents.

information explosion

n. 1. The current period in human history, in which the possession and dissemination of information has supplanted mechanization or industrialization as a driving force in society. 2. The rapid growth in the amount of information available today. Also called information revolution.

Information Highway

or information highway n. See Information Superhighway (definition 1).

information processing

n. The acquisition, storage, manipulation, and presentation of data, particularly by electronic means.

information retrieval

n. The process of finding, organizing, and displaying information, particularly by electronic means.

information science

n. The study of how information is collected, organized, handled, and communicated. See also information theory.

Information Superhighway

n. The existing Internet and its general infrastructure, including private networks, online services, and so on. See National Information Infrastructure.

information warehouse

n. The total of an organization's data resources on all computers.

infrared

adj. Having a frequency in the electromagnetic spectrum in the range just below that of red light. Objects radiate infrared in proportion to their temperature. Infrared radiation is traditionally divided into four somewhat arbitrary categories based on its wavelength. k:\compdict\database\2261.doc Acronym: IR.

Infrared Data Association

n. The industry organization of computer, component, and telecommunications vendors who have established the standards for infrared communication between computers and peripheral devices such as printers. Acronym: IrDA.

infrared port

n. An optical port on a computer for interfacing with an infrared-capable device. Communication is achieved without physical connection through cables. Currently, the devices must be only a few feet apart, and the ports aligned with one another for communication to occur. Infrared ports can be found on some laptops, notebooks, and printers. See also cable, infrared, input/output port.

inherit

vb. To acquire the characteristics of another class, in object-oriented programming. The inherited characteristics may be enhanced, restricted, or modified. See also class.

Initial Graphics Exchange Specification

n. A standard file format for computer graphics, supported by the American National Standards Institute (ANSI), that is particularly suitable for describing models created with computer-aided design (CAD) programs. It includes a wide variety of basic geometric forms (primitives) and, in keeping with CAD objectives, offers methods for describing and annotating drawings and engineering diagrams. See also ANSI. Acronym: IGES.

initialization

n. The process of assigning initial values to variables and data structures in a program.

initialization string

n. A sequence of commands sent to a device, especially a modem, to configure it and prepare it for use. In the case of a modem, the initialization string consists of a string of characters.

initialize

vb. 1. To prepare a storage medium, such as a disk or a tape, for use. This may involve testing the medium's surface, writing startup information, and setting up the file system's index to storage locations. 2. To assign a beginning value to a variable. 3. To start up a computer. See also cold boot, startup.

ink cartridge

n. A disposable module that contains ink and is typically used in an ink-jet printer. See also ink-jet printer.

ink-jet printer

n. A nonimpact printer in which liquid ink is vibrated or heated into a mist and sprayed through tiny holes in the print head to form characters or graphics on the paper. Ink-jet printers are competitive with some laser printers in price and print quality if not in speed. However, the ink, which must be highly soluble to avoid clogging the nozzles in the print head, produces fuzzy-looking output on some papers and smears if touched or dampened shortly after printing. See also nonimpact printer, print head.

inline image

n. An image that is embedded in a line of text rather than in its own window.

inline style

n. A method of applying cascading style sheet properties and values to an element on a page, such as a table, image, or ActiveX control. You can use this method even if the page is not linked to an external style sheet or does not contain an embedded style sheet. See also cascading style sheet, embedded style sheet, external style sheet.

inoculate

vb. To protect a program against virus infection by recording characteristic information about it. For example, checksums on the code can be recomputed and compared with the stored original checksums each time the program is run; if any have changed, the program file is corrupt and may be infected. See also checksum, virus.

input¹

n. Information entered into a computer or program for processing, as from a keyboard or from a file stored on a disk drive.

input²

vb. To enter information into a computer for processing.

input device

n. A peripheral device whose purpose is to allow the user to give input to a computer system. Examples of input devices are keyboards, mice, joysticks, and styluses. See also peripheral.

input/output

n. The complementary tasks of gathering data for a computer or a program to work with, and of making the results of the computer's activities available to the user or to other computer processes. Gathering data is usually done with input devices such as the keyboard and the mouse, as well as disk files, while the output is usually made available to the user via the display and the printer and via disk files or communications ports for the computer. Acronym: I/O.

Insert key

n. A key on the keyboard, labeled "Insert" or "Ins," whose usual function is to toggle a program's editing setting between an insert mode and an overwrite mode, although it may perform different functions in different applications. Also called Ins key.

install

vb. 1. To set in place and prepare for operation. Operating systems and application programs commonly include a disk-based installation program that does most of the work of setting up the program to work with the computer, printer, and other devices. Often such a program can check for devices attached to the system, request the user to choose from sets of options, create a place for the program on the hard disk, and modify system startup files as necessary. 2. To transfer one of a limited number of copies of a program to a disk from a copy-protected program disk; a special procedure is needed because the normal method of copying the program has been disabled.

Installable File System Manager

n. In Windows 95, the part of the file system architecture responsible for arbitrating access to the different file system components. Acronym: IFS.

Installer

n. A program, provided with the Apple Macintosh operating system, that allows the user to install system upgrades and make bootable (system) disks.

interactive

adj. Characterized by conversational exchange of input and output, as when a user enters a question or command and the system immediately responds. The interactivity of microcomputers is one of the features that makes them approachable and easy to use.

interactive session

n. A processing session in which the user can more or less continuously intervene and control the activities of the computer. Compare batch processing (definition 2).

interactive television

n. A video technology in which a viewer interacts with the television programming. Typical uses of interactive television include Internet access, video on demand, and video conferencing. See also video conferencing.

interface

n. 1. The point at which a connection is made between two elements so that they can work with each other. 2. Software that enables a program to work with the user (the user interface, which can be a command-line interface, menu-driven, or a graphical user interface), with another program such as the operating system, or with the computer's hardware. 3. A card, plug, or other device that connects pieces of hardware with the computer so that information can be moved from place to place. For example, standardized interfaces such as RS-232-C standard and SCSI enable communications between computers and printers or disks. See also RS-232-C standard, SCSI. 4. A networking or communications standard, such as the ISO/OSI model, that defines ways for different systems to connect and communicate.

interlaced GIF

n. A GIF (Graphics Interchange Format) image that is gradually displayed in a Web browser, showing increasingly detailed versions of the entire image until all of the data has finished downloading. See also GIF.

interleave

vb. To arrange the sectors on a hard disk in such a way that after one sector is read, the next sector in numeric sequence will arrive at the head when the computer is ready to accept it rather than before, which would make the computer wait a whole revolution of the platter for the sector to come back. Interleaving is set by the format utility that initializes a disk for use with a given computer.

internal modem

n. A modem constructed on an expansion card to be installed in one of the expansion slots inside a computer. Compare external modem, integral modem.

internet

n. Short for internetwork. A set of computer networks that may be dissimilar and are joined together by means of gateways that handle data transfer and conversion of messages from the sending networks' protocols to those of the receiving network.

Internet

n. The worldwide collection of networks and gateways that use the TCP/IP suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational, and other computer systems, that route data and messages. One or more Internet nodes can go off line without endangering the Internet as a whole or causing communications on the Internet to stop, because no single computer or network controls it. The genesis of the Internet was a decentralized network called ARPANET created by the Department of Defense in 1969 to facilitate communications in the event of a nuclear attack. Eventually other networks, including BITNET, Usenet, UUCP, and NSFnet, were connected to ARPANET. Currently, the Internet offers a range of services to users, such as FTP, e-mail, the World Wide Web, Usenet news, Gopher, IRC, telnet, and others. Also called Net. See also BITNET, FTP¹ (definition 1), Gopher, IRC, NSFnet, telnet¹, Usenet, UUCP, World Wide Web.

Internet access

n. 1. The capability of a user to connect to the Internet. This is generally accomplished through one of two ways. The first is through a dialing up of an Internet service provider or an online information services provider via a modem connected to the user's computer. This method is the one used by the majority of home computer users. The second way is through a dedicated line, such as a T1 carrier, that is connected to a local area network, to which, in turn, the user's computer is connected. The dedicated line solution is used by larger organizations, such as corporations, which either have their own node on the Internet or connect to an Internet service provider that is a node. A third way that is emerging is for users to use set-top boxes with their TVs. Generally, however, this will give a user access only to documents on the World-Wide Web. See also dedicated line (definition 1), ISP, LAN, modem, node (definition 2), set-top box. 2. The capability of an online information service to exchange data with the Internet, such as e-mail, or to offer Internet services to users, such as newsgroups, FTP, and/or the World Wide Web. Most online information services offer Internet access to their users. See also FTP¹ (definition 1), online information service.

Internet access device

n. A communications and signal-routing mechanism, possibly incorporating usage tracking and billing features, for use in connecting multiple remote users to the Internet.

Internet account

n. A generic term for a registered username at an Internet Service Provider (ISP). An Internet account is accessed via username and password. Services such as dial-in PPP Internet access and e-mail are provided by ISPs to Internet account owners.

Internet address

n. See domain name address, e-mail address, IP address.

Internet Architecture Board

n. The body of the Internet Society (ISOC) responsible for overall architectural considerations regarding the Internet. The IAB also serves to adjudicate disputes in the standards process. See also Internet Society. Acronym: IAB.

Internet Assigned Numbers Authority

n. A unit of the Internet Architecture Board that registers and controls the assignment of various Internet-related numerical designations, such as IP port, protocol, and enterprise numbers. Acronym: IANA.

Internet backbone

n. One of several high-speed networks connecting many local and regional networks, with at least one connection point where it exchanges packets with other Internet backbones. Historically, the NSFnet (predecessor to the modern Internet) was the backbone to the entire Internet in the United States. This backbone linked the supercomputing centers that the National Science Foundation (NSF) runs. Today, different providers have their own backbones so that the backbone for the supercomputing centers is independent of backbones for commercial Internet providers such as MCI and Sprint. See also backbone.

Internet broadcasting

n. Broadcasting of audio, or audio plus video, signals across the Internet. Internet broadcasting includes conventional over-the-air broadcast stations that transmit their signals into the Internet as well as Internet-only stations. Listeners use audio Internet software, such as RealAudio. One method of Internet broadcasting is MBONE. See also MBONE, RealAudio.

Internet Draft

n. A document produced by the IETF (Internet Engineering Task Force) for purposes of discussing a possible change in standards that govern the Internet. An Internet Draft is subject to revision or replacement at any time; if not replaced or revised, the Internet Draft is valid for no more than six months. An Internet Draft, if accepted, may be developed into an RFC. See also IETF, RFC.

Internet Engineering Steering Group

n. The group within the Internet Society (ISOC) that, along with the Internet Architecture Board (IAB), reviews the standards proposed by the Internet Engineering Task Force (IETF). Acronym: IESG.

Internet Explorer

n. Microsoft's Web browser, introduced in October 1995. Internet Explorer is now available in Windows and Macintosh versions. Later versions provide the ability to incorporate advanced design and animation features into Web pages and recognize ActiveX controls and Java applets. See also ActiveX controls, Java applet, Web browser.

Internet gateway

n. A device that provides the connection between the Internet backbone and another network, such as a LAN (local area network). Usually the device is a computer dedicated to the task or a router. The gateway generally performs protocol conversion between the Internet backbone and the network, data translation or conversion, and message handling. A gateway is considered a node on the Internet. See also gateway, Internet backbone, node (definition 2), router.

Internet Group Membership Protocol

n. A protocol used by IP hosts to report their host group memberships to any immediately neighboring multicast routers. Acronym: IGMP.

Internet Information Server

n. Microsoft's brand of Web server software, utilizing Hypertext Transfer Protocol to deliver World Wide Web documents. It incorporates various functions for security, allows for CGI programs, and also provides for Gopher and FTP servers.

Internet Research Steering Group

n. The governing body of the Internet Research Task Force (IRTF). Acronym: IRSG.

Internet Research Task Force

n. A volunteer organization that makes long-term recommendations concerning the Internet to the Internet Architecture Board. See also Internet Society. Acronym: IRTF.

Internet security

n. A broad topic dealing with all aspects of data authentication, privacy, integrity, and verification for transactions over the Internet. For example, credit card purchases made via a World Wide Web browser require attention to Internet security issues to ensure that the credit card number is not intercepted by an intruder or copied from the server where the number is stored, and to verify that the credit card number is actually sent by the person who claims to be sending it.

Internet Society

n. An international organization, comprising individuals, companies, foundations, and government agencies, that promotes the use, maintenance, and development of the Internet. The Internet Architecture Board (IAB) is a body within the Internet Society. In addition, the Internet Society publishes the Internet Society News and produces the annual INET conference. See also INET (definition 2), Internet Architecture Board. Acronym: ISOC.

Internet Software Consortium

n. A nonprofit organization that develops software that is available for free, via the World Wide Web or FTP, as well as development of Internet standards such as the Dynamic Host Configuration Protocol (DHCP). See also DHCP.

internetwork

adj. Of or pertaining to communications between connected networks. Often used to refer to communication between one local area network and another over the Internet or another wide-area network. See also LAN, wide area network.

InterNIC

n. Short for NSFnet (Internet) Network Information Center. The organization that is charged with registering domain names and IP addresses as well as distributing information about the Internet. InterNIC was formed in 1993 as a consortium involving the U.S. National Science Foundation, AT&T, General Atomics, and Network Solutions Inc. (Herndon, Va.). The latter partner administers InterNIC Registration Services, which assigns Internet names and addresses. InterNIC can be reached by e-mail at info@internic.net or on the Web at http://www.internic.net/.

interoperability

n. Referring to components of computer systems that are able to function in different environments. For example, Microsoft's NT operating system is interoperable on Intel, DEC Alpha, and other CPUs. Another example is the SCSI standard for disk drives and other peripheral devices that allows them to interoperate with different operating systems. With software, interoperability occurs when programs are able to share data and resources. Microsoft Word, for example, is able to read files created by Microsoft Excel.

interpreter

n. A program that translates and then executes each statement in a program written in an interpreted language. See also compiler, interpreted language, language processor.

interrupt

n. A request for attention from the processor. When the processor receives an interrupt, it suspends its current operations, saves the status of its work, and transfers control to a special routine known as an interrupt handler, which contains the instructions for dealing with the particular situation that caused the interrupt. Interrupts can be generated by various hardware devices to request service or report problems, or by the processor itself in response to program errors or requests for operating-system services. Interrupts are the processor's way of communicating with the other elements that make up a computer system. A hierarchy of interrupt priorities determines which interrupt request will be handled first if more than one request is made. A program can temporarily disable some interrupts if it needs the full attention of the processor to complete a particular task. See also exception, external interrupt, hardware interrupt, internal interrupt, software interrupt.

interrupt handler

n. A special routine that is executed when a specific interrupt occurs. Interrupts from different causes have different handlers to carry out the corresponding tasks, such as updating the system clock or reading the keyboard. A table stored in low memory contains pointers, sometimes called vectors, that direct the processor to the various interrupt handlers. Programmers can create new interrupt handlers to replace or supplement existing handlers, such as by making a clicking sound each time the keyboard is pressed.

intranet

n. A network designed for information processing within a company or organization. Its uses include such services as document distribution, software distribution, access to databases, and training. An intranet is so called because it usually employs applications associated with the Internet, such as Web pages, Web browsers, FTP sites, e-mail, newsgroups, and mailing lists, accessible only to those within the organization.

intraware

n. Groupware or middleware for use on a company's private intranet. Intraware packages typically contain e-mail, database, workflow, and browser applications. See also groupware, intranet, middleware.

intruder

n. An unauthorized user or unauthorized program, generally considered to have malicious intent, on a computer or computer network. See also bacterium, cracker, Trojan horse, virus.

Invalid Page Fault

n. See page fault.

I/O

n. See input/output.

I/O controller

n. See input/output controller.

I/O device

n. See input/output device.

I/O port

n. See input/output port.

I/O processor

n. See input/output processor.

IO.SYS

n. One of two hidden system files installed on an MS-DOS startup disk. IO.SYS in IBM releases of MS-DOS (called IBMBIO.COM) contains device drivers for peripherals such as the display, keyboard, floppy disk drive, hard disk drive, serial port, and real-time clock. See also MSDOS.SYS.

IP

n. Acronym for Internet Protocol. The protocol within TCP/IP that governs the breakup of data messages into packets, the routing of the packets from sender to destination network and station, and the reassembly of the packets into the original data messages at the destination. IP corresponds to the network layer in the ISO/OSI model. See also ISO/OSI model, TCP/IP. Compare TCP.

IP address

n. Short for Internet Protocol address. A 32-bit (4-byte) binary number that uniquely identifies a host (computer) connected to the Internet to other Internet hosts, for the purposes of communication through the transfer of packets. An IP address is expressed in "dotted quad" format, consisting of the decimal values of its four bytes, separated with periods; for example, 127.0.0.1. The first one, two, or three bytes of the IP address, assigned by InterNIC Registration Services, identify the network the host is connected to; the remaining bits identify the host itself. The 32 bits of all 4 bytes together can signify almost 2³², or roughly 4 billion, hosts. (A few small ranges within that set of numbers are not used.) See also host, InterNIC, IP, packet (definition 2). Compare domain name.

IP address mask

n. A range of IP addresses defined so only computers with IP addresses within the range are allowed access to an Internet service. To mask a portion of the IP address, replace it with the asterisk wild card character (*). For example, 192.44.*.* represents every computer on the internet with an IP address beginning with 192.44.

IPC

n. See interprocess communication.

IP multicasting

n. Short for Internet Protocol multicasting. The extension of local area network multicasting technology to a TCP/IP network. Hosts send and receive multicast datagrams, the destination fields of which specify IP host group addresses rather than individual IP addresses. A host indicates that it is a member of a group by means of the Internet Group Management Protocol. See also datagram, Internet Group Membership Protocol, IP, MBONE, multicasting.

IPng

Acronym for Internet Protocol next generation. A version of Internet Protocol (IP) developed by the Internet Engineering Task Force (IETF). Improvements over the original Internet Protocol include better security and an increased IP address size of 16 bytes. See also IETF, IP, IP address.

IP spoofing

n. The act of inserting a false sender IP address into an Internet transmission in order to gain unauthorized access to a computer system. See also IP address, spoofing.

IP switching

n. A technology developed by Ipsilon Networks (Sunnyvale, CA) that enables a sequence of IP packets with a common destination to be transmitted over a high-speed, high-bandwidth Asynchronous Transfer Mode (ATM) connection.

IPv6

n. Short for Internet Protocol version 6. A proposed next generation for the Internet Protocol, currently version 4, which was introduced in September 1995 by the Internet Engineering Task Force and formerly known as IPng. See also IP, IPng.

IPX

n. Acronym for Internetwork Packet Exchange. The protocol in Novell NetWare that governs addressing and routing of packets within and between LANs. IPX packets can be encapsulated in Ethernet packets or Token Ring frames. IPX operates at ISO/OSI levels 3 and 4 but does not perform all the functions at those levels. In particular, IPX does not guarantee that a message will be complete (no lost packets); SPX has that job. See also Ethernet, packet, Token Ring network. Compare SPX (definition 1).

IPX/SPX

n. The network and transport level protocols used by Novell NetWare, which together correspond to the combination of TCP and IP in the TCP/IP protocol suite. See also IPX, SPX (definition 1).

IRC

n. Acronym for Internet Relay Chat. A service that enables an Internet user to participate in a conversation on line in real time with other users. An IRC channel, maintained by an IRC server, transmits the text typed by each user who has joined the channel to all other users who have joined the channel. Generally, a channel is dedicated to a particular topic, which may be reflected in the channel's name. An IRC client shows the names of currently active channels, enables the user to join a channel, and then displays the other participants' words on individual lines so that the user can respond. IRC was invented in 1988 by Jarkko Oikarinen of Finland. See also channel (definition 2), server (definition 2).

IRQ

n. Acronym for interrupt request. One of a set of possible hardware interrupts, identified by a number, on a Wintel computer. The number of the IRQ determines which interrupt handler will be used. In the AT bus, ISA, and EISA, 15 IRQs are available; in Micro Channel Architecture, 255 IRQs are available; each device's IRQ is hardwired or set by a jumper or DIP switch. The VL bus and the PCI local bus have their own interrupt systems, which they translate to IRQ numbers. See also AT bus, DIP switch, EISA, interrupt, IRQ conflict, ISA, jumper, Micro Channel Architecture, PCI local bus, VL bus.

IRQ conflict

n. The condition on a Wintel computer in which two different peripheral devices use the same IRQ to request service from the central processing unit (CPU). An IRQ conflict will prevent the system from working correctly; for example, the CPU may respond to an interrupt from a serial mouse by executing an interrupt handler for interrupts generated by a modem. IRQ conflicts can be prevented by the use of Plug and Play hardware and software. See also interrupt handler, IRQ, Plug and Play.

ISAPI

n. Acronym for Internet Server Application Programming Interface. An easy-to-use, high-performance interface for back-end applications for Microsoft's Internet Information Server (IIS). ISAPI has its own dynamic-link library, which offers significant performance advantages over the CGI (Common Gateway Interface) specification. See also API, dynamic-link library, Internet Information Server. Compare CGI.

ISA slot

n. A connection socket for a peripheral designed according to the ISA (Industry Standard Architecture) standard, which applies to the bus developed for use in the 80286 (IBM PC/AT) motherboard. See also ISA.

ISDN

n. Acronym for Integrated Services Digital Network. A worldwide digital communications network evolving from existing telephone services. The goal of ISDN is to replace the current telephone network, which requires digital-to-analog conversions, with facilities totally devoted to digital switching and transmission, yet advanced enough to replace traditionally analog forms of data, ranging from voice to computer transmissions, music, and video. ISDN is built on two main types of communications channels: a B channel, which carries data at a rate of 64 Kbps (kilobits per second), and a D channel, which carries control information at either 16 or 64 Kbps. Computers and other devices connect to ISDN lines through simple, standardized interfaces. When fully implemented (possibly around the turn of the century), ISDN is expected to provide users with faster, more extensive communications services. See also channel (definition 2).

ISDN terminal adapter

n. The hardware interface between a computer and an ISDN line. See also ISDN.

ISO

n. Short for International Organization for Standardization (often incorrectly identified as an acronym for International Standards Organization), an international association of countries of which each is represented by its leading standard-setting organization--for example, ANSI (American National Standards Institute) for the United States. The ISO works to establish global standards for communications and information exchange. Primary among its accomplishments is the widely accepted ISO/OSI model, which defines standards for the interaction of computers connected by communications networks. ISO is not an acronym; rather, it is derived from the Greek word isos, which means "equal" and is the root of the prefix "iso-."

ISO 9660

n. An international format standard for CD-ROM adopted by the ISO that follows the recommendations embodied in the High Sierra specification, with some modifications. See also High Sierra specification.

ISO/OSI model

n. Short for International Organization for Standardization Open Systems Interconnection model. A layered architecture (plan) that standardizes levels of service and types of interaction for computers exchanging information through a communications network. The ISO/OSI model separates computer-to-computer communications into seven layers, or levels, each building upon the standards contained in the levels below it. The lowest of the seven layers deals solely with hardware links; the highest deals with software interactions at the application-program level. k:\compdict\database\3778.doc

ISP

n. Acronym for Internet service provider. A business that supplies Internet connectivity services to individuals, businesses, and other organizations. Some ISPs are large national or multinational corporations that offer access in many locations, while others are limited to a single city or region. Also called access provider, service provider.

italic

n. A type style in which the characters are evenly slanted toward the right. This sentence is in italics. Italics are commonly used for emphasis, foreign-language words and phrases, titles of literary and other works, technical terms, and citations. See also font family. Compare roman.

IVUE