I

I – I-Beam (computer/Windows) to Iterative Optical Processor: IOP (photonics)

I-Beam (computer/Windows)
Shape assumed by the mouse pointer in a text box or word processing document, or when using the text tool in Paintbrush. The I-beam allows repositioning of the insertion point.

IBEW (A/V, electrical)
International Brotherhood of Electrical Workers: union for studio and master control engineers, (in audio/visual and broadcasting) it may also include various floor personnel.

IBM PC (computer)
Series of personal computers from IBM introduced in 1981.

IBM PC-compatible (computer)
Personal computer that is compatible with the IBM PC and PS/2 standards.

IBM PC Character Set (computer/Windows)
Character set used by non-Windows applications. The first 128 characters (including the control characters, the uppercase and lowercase alphabet, the numerals, and the standard punctuation symbols) are the same as the ANSI eight-bit character set used by Windows. The high-bit section of the IBM PC character set (characters with values from 128 - 255), however, differs from the high-bit section of the Windows character set.

IBM PS/2 (computer)
Series of personal computers from IBM introduced in 1987 (superseded IBM-PC line).

IC: Integrated Circuit (computer/microelectronics)
Solid-state microcircuit consisting of interconnected active and passive devices diffused into a single silicon chip (also called monolithic IC). The EIA (Electrical Industries Association) definition is as follows: "The physical realization of a number of electrical elements inseparably associated on or within a continuous body of semiconductor material to perform the functions of a circuit: electronic circuits or systems consisting of an interconnected array of very small active and passive elements, inseparably associated on or within a continuous substrate or body. Other names are integrated electronic circuit, integrated electronic system, and integrated microcircuit".

ICCP (computer)
Institute for Certification of Computer Professional: founded in 1973, it is an organization of computing societies established for the purpose of sponsoring activity in the areas of testing and certification of the knowledge and competence of computing personnel. Its intended goal is to pool the resources of individual societies so that, ultimately, the full attention of the industry may be focused on the vital tasks of developing and recognizing qualified personnel in computing.

IC Socket (computer/microelectronics)
Female contact which provides pluggable electrical engagement on its inner surface for integrated circuit components to achieve interfacing to a printed circuit board.

Icon (computer/Windows)
Small, pictorial representation of an object, such as an application, file or disk drive, that is used in graphical user interfaces (GUIs). The user selects an object by pointing to its icon and clicking the mouse button. Icons can be moved around on the screen. In Windows, a 32 by 32 pixel graphic image, usually in colour. An icon identifies the application in the program manager window when the application is minimised and in other locations in the application chosen by programmers (i.e. Help/About dialog box).

Identifier (computer)
Name usually applied to variable names in program source code. It can be a string of characters used as a name for some element of the program. This element may be a statement label, a procedure or function, a data element (such as a scalar variable or an array) or the program itself: used synonymously with "variable name".

Identity Palette (computer)
In a colour palette of 256 colours, the palette's first and last 10 colours are the standard system colours. The remaining 236 colours are used as a colour lookup table to increase the speed of loading bit maps into the display.

Idle (computer/Windows)
In Windows, the condition or state in which both Windows and the application have processed all pending messages in the queue; from user or hardware-initiated events, and are waiting for the next action, message, request, to occur.

IEC (computer and communications)
International Electrotechnical Commission: IEC is an organisation establishing international standards for electronic components and systems. The IEC is the international equivalent of the RETMA organisation in the United States.

IEEE (computer and communications)
Institute of Electrical and Electronic Engineers - a membership organization that includes engineers, scientists and students in electronics and allied fields. Originating in October, 1951 as The Computer Group of IRE (Institute of Radio Engineers) it was re-named in 1972. IEEE has over 300,000 members and is intimately and intensely involved in setting standards for computers & communications. The Computer Society of the IEEE has over 100,000 members and holds technical conferences on computers, with local meetings to cover current topics of interest.

IEEE 802 Standards (communications, computer, LAN)

IEEE 802.1 Covers network management, other aspects related to Local Area Networks.
IEEE 802.2 Specifies the data link layer for the following access methods:
IEEE 802.3 Specifies CSMA/CD, popularized by Ethernet;
IEEE 802.4 Specifies a token passing bus;
IEEE 802.5 Specifies a token passing ring, popularized by IBM's Token Ring.
IEEE 802.12&14 (specifications for 100 Mbit/sec, CSMA/CD and Token Ring.

IF (computer/DOS)
DOS command evaluates a test, and if true, performs a command. The test can be checking an error level, comparing two strings, or checking if a file exists. The command that this command will perform if true, is often a GOTO or CALL command. If the test is not true, DOS executes the statement immediately following the IF Command.

IFAC (computer)
International Federation of Automatic Control.

IFB (A/V, production)
Interrupted Feedback System: a small earpiece worn by on-the-air talent that carries program sound or the instructions from the director or producer.

IFIB (computer)
International Federation for Information Processing.

If-Then-Else (computer)
High-level programming language statement that compares two or more sets of data and tests the results. If the results are true, the THEN instructions are taken; if not, the ELSE instructions are taken. In some structured programming, the THEN is implied. All statements between the IF and the ELSE are carried out if the condition is true. All instructions between the ELSE and the ENDIF are carried out if the condition is not true.

IGES (computer)
Initial Graphics Exchange Specification - an ANSI standard graphics file format. It is designed to be independent of all CAD and CAM systems. The IGES Organisation is involved with the IGES standard and the PDES format for describing a complete product model. It evolved out of the U.S.A.F. Integrated Computer Automated Manufacturing (ICAM) program in 1979, which developed methods for data exchange that became IGES.

IMA: Interactive Multimedia Association (computer, M/M)
Affiliation of hardware/software producers establishing standards for computer-based multimedia applications, related to cross-platform (i.e. Macintosh and IBM) compatibility, such as the Recommended Practices for Multimedia Portability, 4.1.1, published in 1990.

IMACS (computer)
International Association for Mathematics and Computing in Simulation.

Image Enhancer (A/V, production)
Electronic device used to sharpen video images by exaggerating transitions between light and dark areas in the high-frequency areas of the photographed picture.

Image/Pattern (computer/microelectronics)
In fabrication, the printed screen or design on the substrate after screen printing.

Image Orthicon (A/V)
High sensitivity television camera tube that can be used to pick up scenes of widely varying light values. It is used (one tube) for monochrome television, or in sets of three (Red, Green, Blue tube) for colour television.

Image Processing (A/V, computer)
Analysis of a picture using techniques that can identify shades, colours, and relationships that cannot be perceived by the human eye. It is used to solve identification problems, such as in forensic medicine or in creating weather maps from satellite pictures and deals with images in raster graphics that have been scanned in or captured with digital cameras. Imaging is the recording of pictures into machine format, for example, microfilm, videotape, or computer.


Image Retention (A/V, production)
Tendency of video tubes to retain a "burned in" image of overexposed picture areas.

Imagesetter (computer/printing)
Device for recording high-resolution graphics on photographic film or resin-coated paper.

Imaging (A/V, computer, M/M)
Recording images into machine format (slides, microfilm, videotape, pictures, computer).

Immediate Address (computer)
Machine instruction that contains a value to be used in the execution of the instruction. Most instructions contain only addresses that point to memory locations or peripheral devices where the data is actually stored.

Impact Printer (computer/printing)
Printer that forms characters by physically striking small hammers with the characters at the tips onto a ribbon that presses into the paper: a dot matrix printer has sets of pin hammers that also strike the ribbon and paper.

Impedance (A/V, production)
Resistance to signal flow. It is important in A/V production especially for matching high or low impedance microphones, with high or low impedance recorders. Also, a high impedance microphone works properly only with a relatively short cable (a longer cable has too much resistance), whereas a low impedance microphone can take up to several hundred feet of cable. Impedance is also expressed in high-Z, or low-Z.

Impedance Matching (A/V, communications, computer)
Use of electric circuits and devices to establish the condition in which the impedance of a load is equal to the internal impedance of the source. The condition of impedance match provides for the maximum transfer of power from the source of the power to the load. In a radio transmitter, for example, it is desirable to deliver the maximum power from the power amplifier to the antenna. In audio amplifiers, the requirement is to deliver maximum power to a speaker.

Impedance Transformers (A/V, production)
Allows a high impedance microphone to feed a low impedance recorder ( and vice-versa).

Implementation (computer)
Phase of systems analysis that includes training, equipment conversion, file conversion, system conversion, auditing, evaluation, and maintenance.

Import (computer)
Convert a file in a foreign format to the format of the program being used.

Import Computers (computer/Windows)
In directory replication, the servers or workstations that receive copies of the master set of directories from an export server (see directory replication).

Import Path (computer/Windows)
In directory replication, the path to which imported subdirectories, and the files in those subdirectories, will be stored on an import computer (see directory replication).

Imposition (computer/printing)
Arrangement of pages in a press form so they will appear in correct order when the printed sheet is folded and trimmed.

Impulse Noise (communications)
High amplitude, short-duration noise pulse.

Inactive Window (computer/Windows)
Any open window that the user is not currently working in.

Incandescent Light (A/V, production)
Light produced by the hot tungsten filament of ordinary glass-globe light bulbs.

Incident Light (A/V, production)
Light that strikes the object directly from its source. Incident light reading is the measure of light (in footcandles) from the object that the light falls on. The foot candle meter is pointed directly at the Incident light.

Increment (computer)
Add a number to another: add 1 to a counter or other number to its current value.

Independent Variable (computer)
Input to a model; it is called independent because it can change.

Index (computer term)
With arrays, the position of a particular element with respect to others, usually beginning with 0 as the first element. When used in conjunction with database files or tables, index refers to a lookup table, usually in the form of a file, that relates to the value of a field in the indexed file to its record number. The record number is similar to the index of an array. It indicates the position of the record within a database file, usually the sequence in which the records were originally created and most often starting with 1.

Indexed Addressing (computer)
Referencing memory that can automatically increment the address with the value that is stored in the index register.

Indexed File Organization (computer)
Combination of sequential and direct file organization.

Indexed File Processing (computer)
File organization that represents a compromise between sequential and direct methods.

Index Register (computer)
High-speed memory circuit used to hold the current, relative position of an item in a table. At execution time, the index register value is added to the instructions that reference it.




Indirect Access (computer)
Simple computer instruction of an address that points to another location in memory. The address in the instruction itself is called an indirect address, since it references data indirectly by pointing to the address of the data rather than to the data itself.

Indirect Addressing (computer)
Technique for addressing a relative location: the instruction references a location that contains the address of the information, rather than the information itself.

IND$FILE (computer)
IBM mainframe program transferring files from it and a PC looking like a 3270 terminal.

Inductance (computer/microelectronics)
That property of an electric circuit or of two neighbouring circuits whereby an electromotive force (emf) is induced (process of electromagnetic induction) in one of the circuits by a change of current in either of them. The term inductance coil is sometimes used as a synonym for inductor, a device possessing the property of inductance.

Inductance Bridge (computer/microelectronics)
Device for comparing inductances. The inductance bridge is a special case on an alternating current (ac) impedance bridge. The impedance bridge is used to compare impedances which may contain inductance, capacitance, and resistance.

Inductance Measurement (computer/microelectronics)
Determination of an electromagnetic parameter of an electric circuit.

Induction (computer/microelectronics)
Generating electric current in a circuit from the magnetic influence of an adjacent circuit.

Industry Standard Architecture: ISA (computer)
Older specification for the connection plug-in adapter cards with 16-bit memory addressing capability. ISA was the bus structure used in conventional IBM-compatible computers using INTEL 8088(PC), 80286(AT), 80386, 80486 CPU chips (see Bus, EISA, and MCA)

Inference Program (computer)
Processing program in an expert system: it derives a conclusion from the facts and rules contained in the pre-loaded and stored knowledge base within the device's main memory.

Infinite Loop (computer term)
Looping program, flow-control structure, in which the condition to exit the loop and continue with succeeding statements is never fulfilled.

Information Centre (communications, computer)
Unit in an organisation that may offer employees computer and software training, help in getting data from computer systems, and technical assistance.

Information Management (computer)
Discipline that analyses information as an organisational resource.


Information Management System: IMS (computer)
Hierarchical database management system from IBM used on large IBM mainframes.

Information Retrieval (computer)
Science concerned with the structure, analysis, organization, storage, searching, and dissemination of information. An IR system is designed to make available a given stored collection of information items to a user population desiring to obtain access.

Information Science (computer)
Designation for an interdisciplinary field initially concerned with the exponential growth of recorded scientific information.

Information Services (computer)
Unit in an organization that may manage computer resources for that organization: also called computing services, or management information systems (MIS).

Information Systems (computer)
Designation for a collection of people, procedures, and equipment designed, built, operated, and maintained to collect, record, process, store, retrieve, and display information. In practice, the term is used in a very general sense, both in technical literature and in general publication. Sometimes, the term information processing system is used when the focus is on the "processing" rather than on its "use". The term data processing system is used synonymously with information processing system. The difference arises from the point of view of the user of the terms.

Information Theory (communications, computer)
Branch of communication theory devoted to problems in coding. A unique feature of information theory is its use of a numerical measurement of the amount of information gained when the contents of a message are learned. Information Theory relies heavily on the mathematical science of probability. For this reason, information theory is often applied loosely to other probabilistic studies in communications theory, such as signal detection, random noise, and prediction.

Information Utilities (communications, computer)
Term for Consumer-oriented time share services, such as Compuserve, or The Source.

Infrared (communications)
Invisible light at the high end of the light spectrum. Contrast with ultraviolet; light at the low end of the light spectrum.

Infrared Imaging (A/V, communications, computer)
Devices that convert an invisible infrared image into a visible image. Infrared radiation, generally, spans the wavelengths from about 0.8 or 0.9 micrometer to several hundred micrometers. Most infrared imaging devices are designed to operate within broad wavelength regions of atmospheric transparency. The radiation available for imaging may be emitted from objects in the scene of interest (usually at the longer wavelengths called thermal radiation) or reflected. Reflected radiation may be dominated by sunlight or may be from controlled sources such as lasers used specifically as illuminators for the imaging devices. Reflected radiation imaging devices are called active, while those relying on emitted radiation are called passive.

Inches Per Second (A/V, production)
Measurement used to calculate tape speed (audio, video, etc.)

Incoherent Light (photonics)
Light that displays random phase changes (as opposed to coherent light).

Index of Refraction (A/V, photonics)
Characteristic of a medium which dictates the speed of light passing through that medium: it is the speed of light in vacuum divided by the index of refraction.

Indigenous Sound (A/V, production)
Sound that surrounds and encompasses the environment of a news scene: also called ambient sound, background sound, natural sound, and wild sound.

Indirect Narrative (A/V, production)
Voice-over scripting technique in which the text is not directly related to the pictures being watched while the narration is being delivered.

Inheritance (computer)
In Object-oriented programming, the ability of one class of objects to inherit the properties from another class of object-oriented programming.

Inhibit (computer/microelectronic)
Prevent an action, or acceptance of data, by applying an appropriate signal to the appropriate input, generally a logic "0" in positive logic (see enable).

Inhouse (computer)
Applications and operations that take place on the user/computer premises.

Initialize (computer term)
In programming, setting all variables to their default values and resetting the point of execution to the first executable line of code. Initialization is accomplished automatically in Visual Basic when the application is started.

Injection Laser (computer, microelectronics, photonics)
Laser implemented by a sandwich of semi-conductor crystals, also called a laser diode. The electrons are injected into a junction.

Ink (computer/microelectronics)
In hybrid technology, the conductive paste used on thick film materials to form the printed conductor pattern, usually containing metal oxide, glass frit, and solvent.

Ink Holdout (computer/printing)
Characteristic of paper that keeps ink on the surface, rather than being absorbed into the paper's fibres; coated papers have better ink holdout and can reproduce finer halftones.

Ink Jet Printing (computer/printing)
Printing technology in which dots are sprayed onto the paper to form an image; used for both low-quality and high quality output.



Input/Output: I/O (computer/microelectronics)
General term applied to equipment and/or data involved in connecting the CPU (central processing unit) with the outside world (interface with the end-user).

Input/Output Control Systems (computer)
Handling of all input-output operations has become almost exclusively within the control of the Operating System. More specifically, it has become the province of the I/O control system (IOCS), a portion of the computer Operating System.

Input/Output Devices (computer)
Input is the process of translation of incoming information into electronic patterns suitable for computer processing. Output is the reverse process in which the electronic patterns are translated into a form readable by other machines or understandable by the end-user. The translation process is carried out by the input and output devices of the computer system.

Input/Output Instructions (computer)
Instructions that cause a transfer of information between peripheral devices and the main memory of the computer system, and enable the CPU (central processing unit) to control the peripheral devices that are connected to it.

Input Overload Distortion (A/V, production)
Distortion caused by a microphone when subjected to an exceptionally high-volume sound. Condenser microphones are especially prone to this kind of distortion.

Insert (A/V, production)
Shot that looks in (tightly) to the central action being shown (synonym for cut-in).

Insert Editing (A/V, production)
Drop-in, of new video or audio onto a videotape that already has the control track recorded on it.

Insert Key (computer)
Keyboard key used to switch between insert and overwrite mode or to insert an object at the current cursor location on the screen.

Insertion Point (computer/Windows)
Position of the cursor within a block of text, when the cursor is in a text field. Windows calls it a carat. The insertion point usually appears as a flashing vertical bar in an application window or in a dialog box. The text the user types appears to the left of the insertion point, which is pushed to the right as the user types.

Insert Mode (A/V, computer)
Inserting shots in an already existing recording, without affecting shots on either side. In computing terms, a word processing application function for text input where text is inserted at the cursor position without overwriting any text already in the document.

Install Program (computer)
Program that prepares a software application to run in the computer. It copies the files from diskettes or CD-ROM to the hard disk. It may also de-compress files. It may request the user to input a serial number and name to validate and/or personalize the application's startup.

INSTALL (computer/DOS)
DOS Command that executes a TSR (terminate, stay resident) program during processing of the CONFIG.SYS file. It is used with the FASTOPEN,EXE, KEYB, COM, NLSFUNC.EXE, or SHARE.EXE programs.

Installation Specification (computer)
Program on disk and/or hard copy documents from the equipment supplier describing how the product should be installed.

Instance (computer/Windows)
Term describing the temporal existence of a loaded application or one or more of its windows.

Instant Replay (A/V, production)
Repeating for the viewer, often in slow motion, a key play or other important event, immediately after its live occurrence.

Institute of Electrical & Electronic Engineers (see IEEE)

Instruction (computer)
Expression defining a computer operation and identifying its operands.

Instruction Cycle (computer)
Time required to fetch an instruction from memory and execute it.

Instruction Length (computer)
Number of bytes of memory space required to store an instruction.

Instruction Set (computer)
Total list of instructions that a given microprocessor can execute. The commands that a CPU (central processing unit) is capable of executing.

Integer (computer, mathematical term)
Whole number. In programming, an integer is a data type of two bytes (16 bits). Integers may have signs (taking on values from -32,768 to +32,768) or be unassigned. In the latter case, they are called a word and can represent numbers up to 65,535.

Integrated Circuit: IC (computer/microelectronics)
Solid-state microcircuit consisting of interconnected active and passive devices diffused into a single silicon chip (also called monolithic IC). The EIA (Electrical Industries Association) definition is as follows: "The physical realisation of a number of electrical elements inseparably associated on or within a continuous body of semiconductor material to perform the functions of a circuit: electronic circuits consisting of an interconnected array of extremely small active and passive elements, inseparably associated on or within a continuous substrate or body. Other names are integrated electronic circuit, integrated electronic system, and integrated microcircuit".

Integrated Injection Logic (computer/microelectronics)
Integrated circuit logic which uses bipolar transistor gates, making possible large scale integration on silicon for logic arrays and other analog and digital applications.


Integrated Optics (computer/microelectronics/photonics)
Study of optical devices, based on light transmission in waveguides (confinement of light), of the order of the wavelength of the light: the motivation is to enable the combination of individual devices thus miniaturized, through waveguides or other means, into a functional optical system mounted on a small substrate. The result is called an integrated optical circuit: they can contain lasers, switches, polarizers, modulators, detectors, most of all the elements associated with electrical integrated circuits.

Integrated Services Digital Network: ISDN (communications)
Communications network that can provide for all digital transmission and reception of all forms of information (integrated voice, data, video, etc.).

Integrated Software Package (computer)
Set of software applications that typically includes related word processing, spreadsheet, database, graphics, and telecommunications features.

INTEL (computers)
In 1993, Intel regained supremacy in the market for semiconductor devices (microprocessors) from the Japanese (after almost 7 years). Intel's family of chips have included 286 series, 386, 486, and "Pentium" series. Intel was founded in 1968 by Bob Noyce and Gordon Moore in Mountain View, California. A year later it introduced its first product, a 64-bit bipolar static RAM chip. By 1971, its very successful memory chips began to obsolete magnetic cores for memory storage. Although it is best known for its 8086 & Pentium family of microprocessors, Intel actually invented the microprocessor in 1971. In response to a calculator chip order from Japanese manufacturer Busicom, Intel engineer Marcian E. "Ted" Hoff decided it would make more sense to design a general-purpose machine. The resulting 4004 chip was the first ever microprocessor. Throughout the years, Intel has developed a wide variety of chips and board-level industrial applications. Intel started out with 12 people with first year revenues of $20,000. In 35 years, it has grown into a $100 billion dollar company.

Intelligent Building (computer)
Term used to describe a high technology building providing a full range of computer and communications capabilities and services to tenants including: Automation, Cabling (coax, fiber, twisted pair), communications & computer services, satellite, teleport facilities, videoconferencing services (real-time, full-motion, full-screen colour communications.)

Intelligent Database (computer)
Database containing knowledge about the content of the data. A set of validation criteria are stored with each field of data, such as the minimum and maximum values that can be entered or a list of all possible entries.

Intelligent Form (computer)
Data entry application that provides help screens and internal memory commands to aid the user to enter the correct data, in the correct field.

Intelligent Modem (communications, computer)
Modem that responds to commands and can accept new instructions during the transmission process; originally developed by Hayes Microcomputer Products, Inc.


Intensity (computer, photonics, printing)
Energy of a light beam. Energy equals the square of the amplitude of the light beam. In printing terminology, another name for color saturation (see saturation).

Interactive Cable TV (A/V, communications)
Service in which viewers can take part in a TV program by voting on or reacting to issues. It implies full television viewing, in contrast with videotext or teletext services that provide limited animation. Emerging now, all of these services may become commonplace over some form of cable TV channels. A special decoder and keyboard are required.

Interactive Session (computer)
Back-and-forth dialogue between the user and the computer. Contrast with batch session, in which there is no user interaction.

Interactive Tablet (computer)
Peripheral device that uses a stylus-pen for input into a drawing tablet.

Interactive Video (A/V, computer, M/M)
Usage of a videodisc or CD ROM that is controlled by a computer for an interactive education or entertainment program.

Interblock Gap: IBG (computer)
On magnetic tape, the blank space that separates records: also called interrecord gap.

Intercom (A/V, production)
Abbreviation for intercommunication system for all production and engineering personnel involved in the production of a program. The most widely used system has telephone headsets to facilitate voice communications on several wired or wireless channels.

Interface (computer)
Connection and interaction between hardware, software and the user. Hardware interfaces are the plugs, sockets, and cables that carry electrical signals in a prescribed order. Software interfaces are the languages, codes and messages that programs use to communicate with each other, such as between an application program and the operating system. User interfaces are keyboards, mice, dialogs, command languages, menus used for communications between the user and the computer.

Interface Adapter (communications)
In communications, a device that connects the computer to a network.

Interface Message Processor: IMP (communications, computer)
Original term (1970) generally associated with the ARPA (Advanced Research Project Agency, U.S. Dept. of Defence) network which provided a capability for geographically separate computers, called hosts, to communicate with each other via lines leased from a common carrier. Each host was connected into the network through a small, local computer called an IMP. Each IMP, in turn, was connected to one or more other IMP in the network via wideband leased lines (today, now part of Internet).




Interference (communications, photonics)
Sum of two waves with the same frequency; the result depends on their relative amplitudes and phases; therefore the term is used here in connection & reference to coherent light.

Interlace (A/V, production)
Alternating two fields to eliminate large-area flicker (see frame). A description of video generation in which every other line is scanned, taking two passes to refresh the screen. Television technology utilizes an interlaced signal that generates 60 half frames per second, called a field, or the equivalent of 30 full frames per second.

Interleaved (computer)
A method for containing sound and video information in a single file but in separate chunks, so digital images and audio signals may be transferred from a file to the computer's memory without the delays incurred by CD-ROM seek operations.

Interlock (computer)
Device that prohibits an action from taking place.

Intermediate Frequency Amplifier (communications, computer)
Tuned amplifier employed in the amplification of the signals produced by the mixer in a radio receiver. Because the carrier frequency of the modulated signal from the mixer is essentially constant, the resonant frequency of the amplifier is fixed. The proper design of the intermediate-frequency (i-f) amplifier is essential for good selectivity and reproduction of the original transmitted signal. The standard i-f frequency for broadcast radio receivers is 455 kHz (kilohertz); other frequencies depend upon the application, such as TV or Radar receivers.

Intermittent Error (communications, computer)
Error that occurs from time to time, but not consistently (difficult to diagnose & repair).

Intermodulation Distortion Avoidance (A/V)
Ability of an audio or video component or system to pass or amplify a signal consisting of two super-imposed frequencies (for example, 60 and 400 Hz) without changing the basic waveforms, other than in amplitude. Intermodulation distortion is often abbreviated IM or IMD and is expressed in dB (a large, negative value is desired).

Intermodulation Noise (communications)
Noise due to the nonlinear combination of signals of different frequencies.

Internal Command (computer/DOS/Windows)
Commands that are stored in the file CMD.EXE and that reside in memory at all times.

Internal Font (computer)
Font that is built into the read-only memory of a printer.

Internal Interrupt (computer)
Interrupt caused by processing: a request for input or output, or an overflow error.

Internal Key (A/V, production)
Cutout portion of the base picture is filled with the signal that is doing the cutting.

Internal Modem (communications, computer)
Modem on a printed circuit board that is installed in a vacant slot on the computer bus.

Internal Optical System (A/V, production)
Series of mirrors and filters or prisms and filters inside a colour camera that process the three primary light colours (Red, Green, Blue -or- RGB).

Internal Storage (computer)
Electronic circuitry that temporarily holds data and program instruction needed by the CPU (central processing unit): also called memory, main memory, primary memory.

International Standards Organization: ISO (communications, computer)
International group that has developed standards and protocols for communications between computers (see ISO/OSI - Open Systems Interconnection)

Internet (communications, computer)
Public communications network used by private companies, government bodies, and academic institutions, and now, the general public, in over 175 countries. A loose confederation of networks connected through several backbone networks. It is the name given to this collective network of computers and computer networks that are all interconnected. It began with the ARPANET at the U.S. Department of Defense in the 1960’s. One of its original mandates was to be able to communicate and survive after a potential global nuclear war. It was specifically designed to have no central governing authority.

Internet Packet Exchange: IPX (communications)
In Local Area Networking, Novell Netware's native LAN communications protocol, used to move data between server and/or workstation programs running on different nodes.

Internet Protocol: IP (communications/LAN)
Communications protocol. Microsoft uses Microsoft LAN Manager. In Novell Netware IP software tracks the addresses of nodes, routes outgoing messages, and recognizes incoming messages. In wide area networking the Internet's, internetworking protocol provides connectionless service across multiple packet-switched networks. The IP standard communications scheme is specified in RFC 791 (Request for Comments).

Internet Service(s) Provider (ISP)
Organization or commercial enterprise which provides access and services to the Internet.

Internetworking (communications)
To communicate between one network and another network.

Internic
Provides the primary directory & registration series for North American part of the Internet.

Interpolate (computer)
Estimate unknown values that may lie between known values.

Interpret (computer)
Run a program one line at a time: each line is translated first, then executed.

Interpreter (computer/microelectronics)
Program which fetches and immediately executes instructions in high level language. Interpretation and translation are the two basic processes involved in achieving results from computer programs. An interpreter transforms a program directly into a sequence of machine actions, whereas a translator (compiler) transforms a program written in a language into an equivalent program in another language (machine language).

Interpretive Language (computer)
Programming language requiring an interpreter in the computer in order to run it.

Interprocess Communications: IPC (communications, computer)
Exchange of data between one program and another within a computer system, or over a network. It implies a protocol that guarantees a response to a request. Although IPCs are performed automatically by the program, a similar function is performed interactively when users cut and paste information from one file to another.

Interrecord Gap: IRG (computer)
On magnetic tape, the blank space that separates records: also called an interblock gap.

Interrogate (computer)
Search, add, sum up, or count records in a file. Also a test on the status of a terminal.

Interrupt (computer/microelectronics)
Procedure which enables a program being executed by a microprocessor to be temporarily suspended and an alternative program to be executed, then returning to the original program execution, at the point at which the original program was suspended.

Interrupt Access (computer)
Access authority to allow high priority interrupts to be user-introduced at any time.

Interrupt Feedback System: IFB (A/V, productions)
Small earpiece worn by the on-the-air talent (for example, a news anchor person) that carries program sound or the instruction from the director or producer.

Interrupt Latency (computer/microelectronics)
Delay between interrupt request to a microprocessor and acknowledgement of the request.

Interrupt Mask (computer/microelectronics)
Circuitry allowing a program to specify whether or not interrupt requests will be accepted.

Interrupt Priorities (computer)
Sequence of importance assigned to the interrupts in a computer system. If two interrupts occur simultaneously, the interrupt with the highest priority is serviced first. In some systems, a higher-priority interrupt can gain control of the computer while it is processing a lower priority interrupt.

Interrupt Request Lines: IRQ (computer/DOS/Windows)
Hardware lines over which devices can send signals to get the attention of the central processing unit when the device is ready to accept or send information. Typically, each device connected to the computer uses a separate IRQ.

Interrupt Service Routine: ISR (computer/microelectronics)
Program that: stores away the status of various CPU registers; that performs the program called for by the interrupt; that restores the CPU to its pre-interrupt status; and that resumes the interrupted program.

Interrupt Vector (computer/microelectronics)
Two memory locations assigned to an interrupting device and containing starting address and the microprocessor status word for its service routine.

Interrupt Vector Pointer (computer)
In a personal computer, one of 256 pointers that reside in the first 1,025 bytes of memory. Each vector points to an interrupt service routine, which is a BIOS routine, device driver, or user-defined routine that provides detailed instructions for activating peripheral devices or performing some internal function.

Intersect (computer)
In a relational database application, to match two files and produce a third file with records that are common in both.

Interval Arithmetic (computer/mathematics)
Computational method, based on range arithmetic, which is a modification of significant-digit arithmetic that provides for finer resolution to be employed to prevent the loss of information while retaining an indication of accuracy. Interval arithmetic monitors errors dynamically and is applicable in cases where conventional forward error analysis provides boundaries. The valued utility of interval arithmetic is its inherent ability to act as a diagnostic tool; saving human effort which might otherwise be spent on error analysis. It is also useful in laboratory and engineering environments where physical measurements subject to error are used to compute other quantities. Interval Arithmetic results are easily understood. When a computation produces narrow intervals, the drudgery of an error analysis is not required to know what accuracy has been attained.

Interval Timer (computer)
Mechanism, sometimes called a real-time clock, whereby elapsed time can be monitored by a computer system. In most systems, a word (instruction) in memory is set aside to be used as the interval time. This mechanism, usually at the low end of memory, cannot be used for anything else, since the computer is connected to increment the interval timer automatically, by one interval every Millisecond……. Microsecond…… (or other fixed period).

In The Can (A/V, production)
Finished television show, either on film or videotape; it is now "preserved" and can be rebroadcast at any time. It comes from early usage of Film Cans for transporting film.

Into Frame - Out of Frame (A/V, production)
With tape rolling and camera stationary, the subject of interest (a) enters the picture and is centered to become the visual center of attention, or (b) moves from the visual center and departs from the frame.

Intra (communications)
Within a boundary; for example intracity communications refers to operations that take place within the city. By contrast inter-city would mean between cities.

Intranet (communications)
Your own, corporate network. An Intranet can be a private segment of the Internet.

Inverse Square Law (A/V, production)
Law that states: the intensity of light falls off as "1 over distance/squared", from the source. It is valid only for light sources that radiate light uniformly in all direction, but it is not valid for light where a beam is partially columnated (focused), such as from a Fresnel Light, or from an ellipsoidal spot light.

Inverted File (computer)
In database applications, a file indexed on many of the attributes of the data itself.

Inverter (computer/microelectronics)
Circuit whose output is always in the opposite state from the input. This is also called a NOT circuit (a teeter-totter is a mechanical inverter). Also, an electrical circuit that converts dc (direct current) into ac (alternating current).

Invocation Path (computer)
Route used to invoke an object or a routine in a computer program. If the routine is deeply nested, the path may be quite circuitous and involve many conditions in its course.

Invoke (computer)
To cause execution of a block of code, particularly a procedure or subprocedure.

I/O (computer)
Input/Output - a transfer of data between the CPU (central processing unit) and a peripheral device. Every transfer is an output from one device and an input into another.

I/O Bound (computer)
Excessive amounts of time getting data into and out of a computer.

I/O Channel (computer)
Physical, high-speed pathway between the computer and peripheral devices.

I/O Controller (computer/microelectronics)
Control electronics required to interface an I/O device to a microcomputer CPU.

I/O Interface (computer)
Channel between the CPU and a peripheral device. In personal computers, it includes the controller and the cable between the CPU and the peripheral device.

I/O Port (computer)
Connection to a microcomputer CPU providing a data path between the CPU and external devices (keyboard, screen, printer, etc.); may be input, output, or bidirectional.

I/O Processor (computer)
Hardware device or software program dedicated to handling only input/output operations.



ION Deposition (computer/printer)
A printing technology that is used in high-speed page printers. It is similar to laser printing, except that instead of using light to create a charged image on a drum, it uses a printhead that deposits ions onto the drum. After toner is attracted to the ions on the drum, the paper is pressed directly against the drum fusing the toner to the paper. The quality of ion deposition is approaching that of a laser printer; however, the ink has not been embedded into the paper as deeply, and it can smear more easily.

ION Implantation (computer/microelectronics)
Precise and reproducible method of doping semiconductors to achieve a desired characteristic. Ions of the particular dopant are energized and accelerated to the point where they can be driven in a focused beam directly into the silicon wafer. This technique assures uniform, accurately controlled depth of implantation and ionic diffusion.

Ionization (computer/microelectronics)
Process by which an electron is removed from an atom, molecule, or ion. This process is of basic importance to electrical conduction in gases and liquids. In the simplest case, ionization is a transition between an initial state consisting of a neutral atom, and a final state consisting of a positive ion and a free electron. In more complicated cases, a molecule may be converted to a heavy positive ion and a heavy negative ion which are separated.

Ionization Potential (computer/microelectronics)
Potential difference through which a bound electron must be raised to free it from the atom or molecule to which it is attached. In particular, the ionization potential is the difference in potential between the initial state, in which the electron is bound, and the final state, in which the electron is at rest, at infinity.

ION Milling (computer/microelectronics)
VLSI (very large scale integrated circuit) production technique that performs many of the same type of tasks that more traditional wet chemical and plasma etching processes do.

IPC: InterProcess Communications (communications, computer)
Exchange of data between one program and another within a computer system, or over a network. It implies a protocol that guarantees a response to a request. Although IPCs are performed automatically by the program, a similar function is performed interactively when computer users cut and paste information from one file to another.

IPS (A/V, production)
Inches Per Second: used to calculate tape speed (audio, video).

IR Drop (computer/microelectronics)
That component of the potential drop across a passive element (one which is not a seat of electromotive force) in an electric circuit caused by resistance of the element. This potential drop, by definition, is the product of the resistance (R) of the element, and the current (I) flowing through it. The IR drop across a resistor is the difference of potential between the two ends of the resistor. In a simple, direct-current circuit containing a battery and a number of resistors, the sum of all the IR drops around the circuit (including that of the internal resistance of the battery itself) is equal to the electromotive force of the battery. This is a fundamental circuit theorem in the analysis of electrical networking.

IRE (AV, production)
Institute of Radio Engineers.

Iris (A/V, production)
Same as the lens diaphragm: the adjustable component of a camera lens system that allows for the control of the amount of light passing through the lens.

IRMAboard (computer & communications)
Micro to mainframe communications device from DCA Inc. IRMA board emulates an IBM 3278 (mono) or 3279 (colour) mainframe terminal. IRMA is not an acronym.

Iron Oxide (A/V)
Magnetic particles, adhering to the backing layer of video and audio tape, that are rearranged to reproduce a signal by the action of the magnetic heads. Metals other than iron are also used, such as chromium dioxide, used in a type of high energy videotape.

IRQ: Interrupt Request Lines (computer/DOS/Windows)
Hardware lines over which devices can send signals to get the attention of the central processor when the device is ready to accept or send information. Typically, each device connected to the computer uses a separate IRQ.

IS (communications, computer)
Information Systems, or Services: contemporary term for a group of professionals or a computer and communications section in an organization.

ISA (computer)
Industry Standard Architecture - the 8-bit (PC, XT) and 16-bit (AT) buses in IBM's first personal computer series. EISA is a 32-bit extension of ISA. ISA is a specification of the connections to plug-in adapter cards with 16-bit memory addressing capability.

ISAM (computer)
Indexed Sequential Access Method: widely used disk access method that stores data sequentially, while also maintaining an index of key fields to all the records in the file for direct access capability. The sequential order of the file would be the one most commonly used for batch processing and printing.

ISDN (communications)
Integrated Services Digital Network - an international telecommunications standard for transmitting voice, video, and data over a digital communications line. It uses Out-Of-Band signalling, which provides a separate channel for control information. ISDN services come in two forms: (1) Basic Rate Interface (BRI) and (2) Primary Rate Interface (PRI). BRI provides a 144 kilobits per second service, which includes two 64 Kbps "B" channels for voice/data, and one 16 Kbps "D" channel for control information (2B+D). PRI provides a 1.54 megabit per second service, which includes 23, 64 Kbps "B" channels and two 64 Kbps "D" channels (23B+2D).

ISN (communications)
Information Systems Network, AT&T high speed network integrating voice and data.



ISO (computer & communications)
International Standards Organization that sets international standards, founded in 1946 and headquartered in Geneva. It deals with all fields except electrical and electronics, which comes under the jurisdiction of the older International Electrotechnical Commission (IEC), also in Geneva. With regard to information processing standards, ISO and IEC recently created JTC1, the Joint Technical Committee for information technology. ISO carries out its work through more than 160 technical committees and 2,300 subcommittees and working groups and is made up of standards organizations from more than 75 countries, some of them serving as secretariats for these technical bodies. ANSI is the U.S. member body to ISO. For example, the CD-ROM standard for tables of content and file directory entries, originally called the High Sierra Format, has been established as the ISO-9660 standard.

Isochronous Transmission (communications)
Transmission/Reception of digitized information where the exact timing sequence of the data packets is guaranteed by the method (if there is delay, then the delay is exactly timed).

Isolated Camera (A/V, production)
Camera (also called the iso camera) that is used for instant replay or postproduction tapes.

Isolation Diffusion (computer/microelectronics)
In MIC (monolithic integrated circuit) technology, the diffusion step which generates back-to-back junctions to isolate active devices from one another.

Isometric View (computer)
In computer graphics, a picture of a 3-D object that shows all three dimensions in equal proportions. Isometric views exaggerate a dimension, thus distorting true perspective.

Isotropic (communications term)
Identical properties in all directions. Isotropic antennas transmit/receive in all directions.

ISP (see Internet Service Provider)

Iteration (computer)
In programming, iteration is the repeated execution of lines of code or statements, until some condition is satisfied. All worthwhile computer programs are iterative in some way.

Iterative Operation (computer)
Operation requiring successive executions of instructions or processes.

Iterative Optical Processor: IOP (photonics)
Special purpose optical processor that works by performing multiple iterations of an operation (for example, the multiplication of a vector by a matrix).

ITU: International Telecommunications Union (see International Telecommunications Union)