E

E – EAM (computer) to Eyewash (A/V, production)

EAM (computer)
Electronic Accounting Machine: older, archaic term that was used to describe tabulating machines that utilised punch cards for data entry (early data processing systems).

Earphones (communications)
Part of a head-set device that utilises a class of energy transducers capable of receiving alternating current and generating acoustic waves resembling the characteristics of that current. Earphone systems include a driver element with its diaphragm and arrangements for magnetic flux, or electrostatic, or direct electric charge, plus a casing, one or more acoustic cavities and ports, acoustic damping and insulation, and some arrangement for coupling the driver to the human ear. The wiring connecting the precedent amplifier to the driver, which may be incorporated into the earphone system, can be a complicated circuit which feeds, for each of two stereophonic channels, some part of the current to each ear. Time delays and energy ratios at the two earphones are adjusted so that the listener is given the illusion that the sound sources are not "in the head" but are externalised appropriately in all three planes of space.

Earth Station (communications)
Terrestrial, ground-based receiver and/or transmitter station for satellite communications. Depending on the frequency and complexity of the bandwidth used, these earth stations are shaped in dish-form and come in many diameter sizes.

EBCDIC (communications, computer) (phonetically pronounced as ebsidik)
Extended Binary Coded Decimal Interchange Code: similar to ASCII, an 8-bit code that translates character sets into binary numbers. Originally implemented on the IBM 360 mainframes (1960's) it is provided on all IBM mainframe and minicomputers. The 8-bit code represents 256 character combinations. ASCII, is the standard for personal computers.

EBU: European Broadcast Union (A/V)
Organisation establishing audio and video standards for Western Europe. EBU performs functions similar to those of the NTSC and AES in the U.S.A. The EBU is affiliated with DIN and CCITT.

ECC: Error Correction Code (communications, computer)

Coding system that, in conjunction with an Error Detection Coding (EDC) scheme, can reconstruct erroneous data to its original value (see Error Correction/Detection Code)

ECF (communications, computer)
Enhanced Connectivity Facilities: utility software program from IBM providing for DOS-based personal computers to communicate and exchange information from mainframes and minicomputers. The ECF program is loaded into both the personal computer and the mainframe or minicomputer to be communicated with.

Echo (computer/DOS)
DOS command that displays a prompt message during the execution of a batch file, displays the current status of ECHO, or turns the ECHO on or off. It can be used to display an entire screen of text that might offer the user a menu of choices. When ECHO is on, every command is displayed as it is executed. When ECHO is off, commands are processed without displaying.
Echo Box (communications, microelectronics)
Device used to check the output power and spectrum of a radar transmitter. It consists of a low-loss, tunable, resonant cavity connected to the antenna feed line through a fixed coupling circuit so that the fraction of output power supplied to the cavity is always constant. The signal level within the cavity depends on the strength of the portion of the transmitter output spectrum lying within the cavity's narrow passband, which can be tuned to traverse the entire frequency range of interest.

Echo Cancellation (communications)
Isolation feature of modems (modulator/demodulator) that discriminates and filters out undesirable signals caused by echoes on a communicated signal. Echo Cancellation in full-duplex modems provides for the sending and receiving of information in the same bandwidth, at the same frequency (on the same pair of wires).

Echo Check (communications)
Error Checking that "echos" or retransmits information back to the sending unit so that there is a constant comparison of what has been transmitted.

Echo Effect (A/V)
Visually, the same image is repeated as if it were placed between two opposite mirrors.

Echoplex (communications)
Data communications signalling between two stations whereby the sending station's screen displays the data that was transmitted and received by the receiving station, on the sending station's screen (for verification of data transmission accuracy).

Echo Suppressor (communications)
Signalling capability that disables reverse transmission in a communications circuit, or line, making the circuit or connection one-way only. It is used in long-distance global communications to reduce echo effects in telephone conversations.

ECL: Emitter Coupled Logic (computer/microelectronics)
Type of current mode logic whereby the circuits are coupled with one another through emitter followers at the input or output of the logic circuit.

ECMA (computer)
European Computer Manufacturer's Association: membership organisation of computer vendors and business equipment manufacturers and suppliers similar to its counterpart in North America, CBEMA (Computer and Business Equipment Manufacturers Association).

Econometric Application (computer)
Software modelling programs used to better assess the economic environment within which countries or companies operate. Planners are increasing their use of macroeconomic forecasts generated by econometric application models. These models generally perform the forecasting task more efficiently by providing a consistent framework for the analysis of a large number of external variables.

Ed Beta: Extended Definition Beta (A/V)
Better version of the Beta format (Sony) that has better horizontal resolution; it is somewhat similar to S-VHS.

EDC: Error Detection Code (communications, computer)
Coding system that can detect errors in a single byte or in blocks of data. Single-byte errors are caught by parity checkers such as the ones employed in a personal computer's memory system. Errors in blocks of data are commonly determined by using techniques such as the Cyclic Redundancy Codes (CRC) used for data transfer by modem. More sophisticated methods are employed when error correction is required for CD-ROMs.

Eddy Current (computer/microelectronics)
Electric current induced within the body of a conductor when the conductor either moves through a non-uniform magnetic field or is in a region where there is a change in the magnetic flux. Although eddy current can be induced in any electrical conductor, the effect is most pronounced in solid metallic conductors. Eddy current is used in induction heating and to damp out oscillations in various devices.

Edge Connector (computer)
Row of etched lines (usually gold coloured) on the edge of a printed circuit board that can be inserted into an expansion slot on the personal computer backplane or motherboard.

EDI (communications, computer)
Electronic Data Interchange: electronic communication of transactions between organizations. EDI services enable users to interconnect regardless of the type of network or equipment being used, provided the same EDI standard is being supported. Common EDI usage includes exchange items such as invoices and purchase orders.

EDIFACT (communications)
Proposed ISO (International Standards Organisation) standard for Electronic Data Interchange (EDI) to supersede X.12 and Tradacoms, to become a worldwide standard.

Edit (A/V, computer/DOS)
In video production the process of creating a master tape by combining individual video sequences from sources such as videotape, conventional and still video cameras, and still and animated graphics from computers. The master tape is ordinarily used to duplicate multiple videocassettes for distribution. In computing, to change existing information. In DOS Command, after the C prompt, for DOS 5.0 and 6.0, immediately brings to the screen the file specified after "edit" (i.e. edit config.sys brings up the CONFIG.SYS file in the DOS editor (DOS 5.0, DOS 6.0). It can also be invoked from the DOS menu.

Edit Controller (A/V, computer)
Video device connecting two or more videotape playback devices with a videotape recorder and controlling the operation of each device to which it is connected. Edit controllers are programmed from an edit decision list (EDL). In desktop video production, the computer usually takes the place of a dedicated edit controller.

Edit Decision List: EDL (A/V, computer, M/M)
Lists the individual items included in the editing process to create a master videotape. Edit decision lists can be prepared by hand or created and stored on a computer.

Editing (A/V, production)
Process of selecting portions of picture and sound recordings, including their timing and sequence, and the piecing together of these elements into a finished product.

Editing Log (A/V, production)
Listing compiled by the editor during paper-and-pencil editing. It includes the reel and scene numbers, exact addresses of in-and-out cues for each shot, the in-and-out sound cues, prominent ambient sites and sounds, and other editing commentary on tape footage. It is also, sometimes, called the editing shot sheet(s).

Edit Instruction (computer)
Instruction to format a field for display on a screen or to print.

Edit Mode (computer)
Mode, in programming, that allows existing information to be changed.

Editor (computer)
Program designed for manipulation of source program material (also called text editor).

Edit Program (computer)
Data entry program that validates input and stores new information in a file. A program that allows changes to existing information.

Edit Routine (computer)
Set of instructions in a program that verifies that the information is valid.

EDL (A/V, computer, M/M)
Edit Decision List: listing of individual items included in the editing process to create a master videotape. Edit decision lists can be prepared by hand or created on a computer.

EDLIN (computer/DOS)
DOS Command: Older version Line editor in MSDOS and IBM OS/2, allowing for the creation and modification of batch files. EDLIN does not have the menu options available with the DOS 4, 5, or 6 EDIT DOS Editor options in the pull down menu.

EDP (computer)
Electronic Data Processing: older term used to define computing, computer processing.

EDSAC (historic/computer)
Electronic Delay Storage Automatic Calculator: designed according to the principles expounded by J. Presper Eckert, John W. Mauchly, and others at the summer school held in 1946 at the Moore School of Electrical Engineering in Philadelphia. The objectives in mind from the beginning were: to show that a binary stored program computer could be built and operated.

EDVAC (historic/computer)
Electronic Discrete Variable Automatic Computer: a direct outgrowth of the work done with ENIAC. Experience with acoustic delay lines for radar range measurement led to the concept of recirculating storage of digital information. The group at the Moore School of Electrical Engineering at the University of Pennsylvania started development work on mercury delay lines for storage, and initiated the design of EDVAC. The conceptual design of the EDVAC was completed in 1946 and it was delivered in 1949 to the Ballistic Research Laboratories at Aberdeen, Maryland.

EEPROM (computer)
Electrically Erasable Programmable Read Only Memory chips that hold their content without power. They can be erased, either within the computer or externally, and usually require more voltage for erasure than the common +5 volts used in logic circuits. They function like non-volatile RAM, but writing to EEPROM is much slower than writing to RAM. EEPROMs are used in devices that must keep data up-to-date, without power.

Effects (A/V)
Adding effects to a production. An audio term describing addition of echoes and other artificially generated modifications to increase a sound's acoustic realism or to create a particular ambience. In the video field, effects are modifications to an image to increase its visual impact, such as solarization and pixelation. Effects is often abbreviated as FX.

Effects Bus (A/V)
Row of buttons that can generate electronic effects such as keys, wipes, and mattes.

Effect To Cause Approach (A/V, production)
Production approach that starts with the definition of the viewer experience and works backward to the production elements the medium requires in order to produce such a viewer experience.

EFP: Electronic Field Production (A/V, production)
Television production activity outside the studio usually shot for postproduction (not live).

EFP/ENG Cameras (A/V, production)
Electronic field production or electronic news gathering cameras. Replacing film cameras for news reporting, these cameras are portable, self-contained, and largely automated.

EFT (computer)
Electronic Funds Transfer: system and programs used for transactions in currency; paying for goods and services by transferring funds electronically.

EGA: Enhanced Graphics Adapter (computer)
Early video display standard from IBM providing medium-resolution text and graphics. EGA has been superseded by VGA and SVGA.

EIA (communications, computer)
Electronic Industries Association: membership organisation, founded in 1924, that includes manufacturers of electronic parts and systems. The EIA sets electrical and electronic interface standards, such as the EIA RS-232-C interface between computers or terminals and modems; RS-422, a more robust version of the RS-232-C standard; and RS-170-A, the consumer standard for connection of colour NTSC television signals. The EIA/TIA 568A & B (ISO 8877) provide for the communications and cabling guidelines for Local Area Networking.

EIAJ: Electronic Industries Association of Japan (A/V, electronics)
EIAJ established the Type No. 1 Standard for 1/2 inch helical scan videotape recorders. The standard assures that any monochrome tape recorded on one such recorder can be played back on any other monochrome or colour recorder, and any colour tape can be played back on any other colour VTR, provided it meets the EIAJ Type No. 1 Standard.


EIP: Electronic Integrated Publishing (computer/printing)
Use of computers in the publishing process, from concept to the final printed product.

EIS: Electronic Image Stabilizer (A/V)
Feature in camcorders to compensate for camera movement. A servo mechanism, using digital processing, that "floats" the lens or picture to compensate for movement so that the operator can avoid recording shaky pictures (feature of "fuzzy logic").

EIS: Executive Information System (computer)
Term used to describe a program or system for managers and executives within an organisation that more easily summarises information for management decision making.

EISA (computer)
Extended Industry Standard Architecture: pronounced "eesa", it was a bus standard for PCs that extended the AT bus architecture to 32 bits and allowed more than one CPU to share the bus. EISA was announced in late 1988 to compete with IBM's MCA (Micro Channel Architecture). PC and AT boards that couldn’t plug into the IBM Micro Channel, could plug into an EISA slot.

Ejection (computer/microelectronics)
Wipe off (removal) of the printed part from the workholder, in thick film screen printing.

Electret (computer/microelectronics/photonics)
Solid dielectric possessing persistent dielectric polarization. An electret is the analog of a magnet. Electrets are made by cooling suitable dielectrics from elevated temperatures in strong electric fields. A special class, called photoelectrets, is produced by the removal of light from an illuminated photoconductor in an electric field. Electrets can be prepared from certain organic waxes and resins or from ferroelectric crystals or ceramics such as barium titanate. Photoelectrets have been prepared from sulphur, cadmium and zinc sulfides, and anthracene. Electrets are metastable; their polarizations decay slowly after removal of the applied field and more rapidly with increasing temperature. Space-charge polarization is the principal mechanism involved in electret formation.

Electret Transducer (communications)
Device that converts acoustical or mechanical energy into electrical energy, and vice-versa, which utilizes a quasi-permanent charged dielectric material (electret): examples include certain types of microphones, earphones, and sound cartridges. In its simplest implementation, the transducer consists of a metal backplate (first electrode) covered by a mechanically tensioned diaphragm. The diaphragm is a foil electret carrying a metal coating (second electrode) on the side facing away from the backplate. Provision must be made to maintain a shallow air gap between electret and backplate. This air gap is occupied by an electrostatic field originating from the electret charges. Upon acoustical or mechanical deflection of the diaphragm, such a device generates an electrical output signal between its two electrodes: similarly, application of an electrical signal results in diaphragm deflections. Electret devices are therefore self-biased electrostatic or condenser transducers. They exhibit all the advantages of this transducer class, such as wide dynamic range and flat response over a frequency range of several decades, without requiring the external bias necessary in conventional transducers.





Electric Charge (computer/electronics)
Basic property of the elementary particles of matter, it cannot be precisely defined, but must be accepted as a basic experimental quantity that can define other quantities in terms of it. In prehistoric times, humans already understood that rubbing amber with fur produced properties in each that were not possessed before the rubbing. The amber attracted the fur after rubbing, but not before. These new properties were described in early human language as having a "charge". The amber was assigned a negative charge and the fur was assigned a positive charge. When "charge" is used in electricity and electronics, it means the unbalanced charge (excess or deficiency of electrons), so that there are enough "non-normal" atoms to account for the positive charge on a "positively charged body". In the amber experience, the person "rubs" electrons off the fur onto the amber, giving it a surplus of electrons, leaving the fur with a deficiency of electrons.

Electric Current (computer/electronics)
Term used to describe the net transfer of electric charge per unit of time; it is usually measured in amperes. The passage of electric current involves a transfer of energy. Except in the case of superconductivity (cooling to a temperature whereby there is no longer any resistance to the flow of electrons), a current always heats the medium through which it passes. On the other hand, a stream of electrons or ions in a vacuum, which also may be regarded as an electric current, produces no local heating. Measurable current range in magnitude from the nearly instantaneous hundreds of thousands of amperes in lightning strokes, to values of the order of less than 1 trillionth of an amp (less than 1 pico-amp or less than one fempto-amp), which occur in research applications. All matter may be classified as conducting, semiconducting, or insulating, depending upon the ease with which electric current is transmitted through it. Most metals, electrolytic solutions, and highly ionized gases are conductors. Transition elements, such as silicon and germanium, are semiconductors, while most other substances are insulators. Electric current may be direct (dc) or alternating (ac). Direct current (dc) is, necessarily, unidirectional but may be either steady or varying in magnitude. By convention, it is assumed to flow in the direction of motion of positive charges, opposite to the actual flow of electrons. Alternative current (ac) periodically reverses in direction.

Electric Filter (communications, computer/microelectronics)
In electrical systems a transmission matrix or network for selective enhancement or reduction of specified components of an input signal. The filtering is accomplished by selectively attenuating those frequency components of the input signal which are undesired, relative to those which it is desirable to enhance.

Electric Spark (computer/microelectronics)
Term used to describe a transient form of gaseous conduction. It can be thought of as the transition between two more or less stable forms of gaseous conduction. The transitional breakdown which occurs in the transition from a glow to an arc discharge may be thought of as a spark. Lightning may be the most dramatic example. Others include ignition systems for automobiles, intense short-duration illumination in high speed photography, or as a source of excitation in spectroscopy. For photography, the spark may actually perform the function of the camera shutter (extinction renders darkness).

Electric Transient (computer/microelectronics)
Temporary component of current and voltage in an electric circuit which has been disturbed. In ordinary circuit problems, a stabilized condition of the circuit is assumed and steady-state values of current and voltage are sufficient. It often becomes important, however, to know what occurs during the transition period following a circuit disturbance until the steady-state condition is reached. Transients occur only in circuits containing inductance or capacitance. In general, transients accompany any change in the amount or form of energy stored in the circuit.

Electrical Communications (computer/microelectronics)
Science and technology by which information is collected from an originating source, transformed into electric current or fields, transmitted over electrical networks or through space to another point, and reconverted into a form suitable for interpretation by a receiving entity. Some sources produce continuously varying signals. Examples are speech, music, the output of TV cameras, and sensors of temperature, pressure, and the like. Others produce signals whose distinguishing characteristic is that they are on or off. Examples include computers, above-or-below sensors of temperature, or pressure.

Electrical Conduction in Gases (computer/microelectronics)
Process by means of which a net charge is transported through a gaseous medium. It encompasses a variety of effects and modes of conduction. A feature which distinguishes gaseous conduction from conduction in a solid or liquid is the active part which the medium plays in the process. The gas permits the drift of free charges from one electrode to the other, and the gas itself may be ionized to produce other charges which can interact with the electrodes to liberate additional charges. Some commercial applications include gas-filled phototubes, gaseous rectifiers, glow tubes, thyratrons. Gas tubes are used in power supplies, control circuits, pulse generators, voltage regulators. In scientific experiments, gaseous conduction devices are used as ion sources for mass spectrometers and nuclear accelerators, ionization vacuum gauges, radiation detection and measurement instruments, and thermonuclear devices for the production of electric power.

Electrical Element (computer/microelectronics)
Concept, in uncombined form, of the building blocks from which electric circuits are synthesised.

Electrical Impedance (computer/microelectronics)
Term used to describe total opposition that a circuit presents to an alternating current.

Electrical Instability (A/V, computer/microelectronics)
Persistent condition of unwanted self-oscillation in an amplifier or other electrical circuit. Instability is usually caused by excessive positive feedback from the output to the input of an active network. In and audio-frequency amplifier, if instability is at a low audible frequency, the output will contain a putt-putt sound, from which such instability is termed motorboating. The instability may also be at a high audible frequency, or it may be at frequencies outside the audible range. Although such oscillations may not be heard directly, they produce distortion by driving the amplifier beyond its linear range.

Electrical Loading (communications/microelectronics)
Addition of inductance to a transmission line in order to improve its transmission characteristics over the required frequency band. Loading coils are often inserted in telephone lines, at spacing as close as 1 kilometre, to counteract the capacitance of the line and thus make the line impedance more closely equivalent to pure resistance. Similar coils are used between sections of lines used for carrier transmission.

Electrical Measurement (computer/microelectronics)
Term used to describe the measurement of any one of the many quantities by which the behaviour of electricity is characterised. The knowledge of the quantitative behaviour of electricity is essential to scientific and mechanical progress. Electrical measurements play a major role in industry, communications, and such unrelated fields as medicine. Many electrical measurements can be made with direct-indicating instruments merely by connecting the instrument properly in the circuit. A volt-meter provides a pointer which moves over a scale calibrated in volts, an ammeter in the same way presents a reading of current in amperes. Other direct-reading instruments are watt meters, frequency meters, power-factor or phase-angle meters, and ohmmeters. Many electrical quantities are measured both as instantaneous values and as values integrated over time. Some electrical measurements must be made with various specialised devices or systems requiring adjustment or balancing to obtain the measured value. Typical of these are potentiometers and bridges in many standard and specialised forms. Because of differences in instruments and techniques, it is convenient to divide measurements into direct-current (DC) and alternating-current (ac) classes.

Electrical Noise (communications, computer/microelectronics)
Interfering and unwanted current or voltages in an electrical device or system. Electrical noise, usually simply called noise, has an important effect on any electrical system which is used to gather, transmit, process, or present information. In such systems as telephone, radio, television, radar, radionavigation, telemetering, electronic control, or electronic computing, the desired signals carrying intelligence may be masked or distorted by noise. Noise may be classified as either random noise or non-random noise. Random noise is noise that is not predictable, although it may produce statistical regularities. Non-random noise is usually the result of radiation from other electric equipment, unwanted coupling with other systems, or spurious oscillations within an electrical circuit. Noise due to natural phenomena often cannot be reduced below certain fixed levels. For example, a radio receiver cannot operate on received signals which are very weak (compared to some level determined by the thermal noise in the receiver), no matter how much amplification is used in the receiver, because the noise is amplified along with the signal.

Electrical Noise Generator (communications, computer/microelectronics)
Device which produces electrical noise for use in electrical measurements. Electrical noise generators are commonly used in measuring the noise figure of a radio receiver or other amplifier. They are also used in other tests of the response of an electrical system to random noise, and in measurements of noise intensity. Some standard types of noise generators are: diode, gas-discharge tube, hot-wire and klystron.

Electrical Resistance (communications, computer/microelectronics)
Property of an electrically conductive material that causes a portion of the energy of an electric current flowing in a circuit to be converted into heat.

Electrical Shielding (communications, computer/microelectronics)
Means of avoidance of pickup of undesired signals or noise, suppressing radiation of undesired signals, and confining the desired signals to desired paths or regions. These shielding objectives cannot be realised without some degree of modification of the electric and magnetic fields involved; as long as the effects of these modifications do not seriously interfere with wanted objectives. Different types of electrical shielding include: electromagnetic, electrostatic, magnetostatic, shielded wires and cables.

Electroacoustics (A/V, communications, computer/microelectronics)
Part of electronics concerned with the conversion of acoustical energy into electrical energy or vice-versa. These means of conversion are termed electroacoustic transducers or electroacoustic systems. They are used in magnetic tape reproducers, motion picture, phonographic, radio, sound, and telephone reproducers, and sound-reinforcement systems for converting acoustical waves at the input into corresponding electrical waves, and for converting electrical waves at the output into corresponding sound waves.

Electrochromic Displays (A/V, computer)
Devices that employ a reversible electrochemical reaction to cause a change in color of segments patterned to form graphics or characters. Electrochromic displays (ECDs) are passive devices that only modulate ambient light, in contrast to a light-emitting diode (LED). They operate at low voltages and have a low enough energy requirement that a watch-size display can be operated for about two years from a small commercial battery. In the off state, the segments are typically colourless; in the on state, they are brightly colored, for example, blue, gray, or purple. Electrochromic displays are most efficiently utilized in applications requiring the display of large-format, slowly changing information, such as in clocks or message boards.

Electroluminescence (computer/microelectronics)
Luminescence from the application of an electric field to a material, usually a solid. In addition to the use in modern electroluminescent lamps, electroluminescent materials may be employed in display devices and, when used in conjunction with photoconductors, in light amplifiers and in logic circuits for computers (much slower than semiconductors).

Electromagnetic Compatibility (communications)
Capability of electronic equipment or systems to be operated in the intended electromagnetic environment at designed levels of efficiency. The electromagnetic environment existing at the input or antenna terminal of a receiver is a mixture of signals from many sources. This mixture consists of both a desired signal and many undesired signals to which the receiver may be sensitive. These undesired or interference signals may come from equipment intended to radiate for the purpose of communications or from sources not intended to radiate electromagnetic energy for the purpose of transferring information. In addition to mutual interference between systems, the possibility of extraneous energy generated within a system interfering with its own operation also exists. The subject of electromagnetic compatibility deals with reducing the source of interference & its effect on reception of the desired signals.

Electromagnetic Focus (A/V, microelectronics)
One of two methods of focusing an electron beam, the other being electrostatic. Electromagnetic focus utilises a magnetic field.

Electromagnetic Interference: EMI (communications, computer)
Interference that is caused by spurious or steady-state radiation coming from devices that may disrupt the operation of a computer, communications, or electronic system.

Electromagnetic Spectrum (communications)
Range of electromagnetic radiation. All radiating energy in the universe is classified as electromagnetic radiation, which includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, radar.

Electromagnetic Wave Transmission (communications)
Transmission of electrical energy by wires, cables, by broadcasting of radio signals, and the phenomenon of visible light are all examples of the propagation of electromagnetic energy. Electromagnetic energy travels in the form of a wave. Its un-impeded speed of travel is approximately 186,000 miles, or 300,000 kilometres, per second. Electromagnetic waves do not penetrate far into an electrical conductor, and a wave that is incident on the surface of a good conductor is largely reflected. Electromagnetic waves originate from accelerated electric charges. A radio wave originates from the oscillatory acceleration of electrons in the transmitting antenna. The light that is produced with a laser, originates when electrons fall from a higher energy level to a lower one. The waves emitted from a source are oscillatory in character and are described in terms of their frequency of oscillation. Local telephone (not using carrier systems) carry electromagnetic waves with frequencies of about 200 to 4,000 Hz (cycles per second). Medium-wave radio uses frequencies of the order of 1 million Hz (megahertz, MHz). Radar uses frequencies of the order of 1 billion Hz (gigahertz, GHz). Ruby lasers emit light with frequencies above 100 trillion Hz (terahertz, THz).

Electromotive Force: EMF (communications, computer/microelectronics)
Term that defines the work per unit charge required to carry a small positive charge around a path: the electromotive force around a closed path in an electric field. It is also defined as the line integral of the electric intensity around a closed path in the field.

Electron Beam Bonding (computer/microelectronics)
Fabrication using a stream of electrons to heat and bond two conductors in a vacuum.

Electron Beam Lithography (computer/microelectronics)
Lithography in which a radiation-sensitive film (resistor) is placed in the vacuum chamber of a scanning beam electron microscope and exposed by an electron beam under computer control.

Electron Beam Welding (computer/microelectronics)
Fabrication process whereby a welder generates a stream of electrons travelling at up to 60% of the speed of light, focusing the electrons to a small, precisely controlled spot in a vacuum, and converts the kinetic energy into extremely high temperature on impact.

Electron Emission (computer/microelectronics)
Liberation of electrons from a substance into a vacuum. Since all substances are made of atoms and since all atoms contain electrons, any substance may emit electrons; usually, however, the term refers to emission of electrons from the surface of a solid. If a substance is heated, the atoms begin to vibrate with larger amplitudes, and electrons may absorb sufficient energy from these vibrations to be emitted in the process known as thermionic emission. Electrons may also be liberated upon irradiation of the substance with light (photoemission). Electron emission from a substance may be induced by bombardment with charged particles such as electrons or ions in the phenomenon called secondary emission. Field emission, or cold emission, refers to the emission of electrons under the influence of a strong electric field. Electrons may also be emitted from one solid into another: referred to as electron injection.

Electron Gun (A/V)
Device in a camera or monitor tube firing electrons at the image-sensing or reproducing surface of the picture tube. The beam is deflected to perform the scanning function.

Electron Lens (A/V, computer/microelectronics)
Electric or magnetic field (or a combination) which acts upon an electron beam in a manner similar to the way an optical lens acts upon a light beam. Electron lenses find application for the formation of sharply focused electron beams, as in cathode-ray tubes, and for the formation of electron images, as in infrared converter tubes, various types of TV camera tubes, and electron microscopes. Any electric or magnetic field which is symmetrical about an axis is capable of forming either a real or a virtual electron image of an object on the axis which either emits electrons or transmits electrons from another electron source. An axially symmetric electric or magnetic field is analogous to a spherical optical lens. Electron lenses differ from optical lenses in the fact that the index of refraction is continuously variable and that it covers an enormous range.

Electron Motion In Vacuum (computer/microelectronics)
Motion of electrons in a space freed sufficiently from matter so that collisions with other particles play a negligible role. The motion of electrons in a vacuum is controlled by electric and magnetic fields whose force on the electrons is proportional to their magnitude. Electric and magnetic fields may arise from electrodes, current, and magnets surrounding the evacuated space in which a particular electron moves, as well as from the presence of other charged particles within the space.

Electron Optics or Electro-Optics (A/V, computer/microelectronics)
Branch of physics concerned with the motion of free electrons under the influence of electric and magnetic fields. The term is derived from the fact that the laws governing electron paths in such fields are formally identical with those governing light rays in media of varying refractive index. Electron Optics finds application in the formation of electron beams, as in cathode-ray tubes and television camera tubes; in the deflection of such beams by electric and magnetic fields; and in the formation of electron images, as in electron microscopes and image tubes.

Electron Tube (A/V, computer/microelectronics)
Device in which conduction takes place by the movement of electrons or ions between electrodes through a vacuum, or ionised gas with a gas-tight envelope. Electron tubes include all partially evacuated tubes whose electrical characteristics are derived from the flow of electrons through the tube. Two subclasses of electron tubes are vacuum tubes and gas-filled tubes. Vacuum tubes are evacuated to such a degree that their electrical characteristics are essentially unaffected by the presence of any residual gas or vapour. Gas-filled tubes have electrical characteristics that are substantially dependent upon the ionisation of deliberately introduced gas or vapor. Electrical characteristics of electron tubes vary among the numerous types, depending upon the number and configuration of the electrodes, upon the degree of evacuation, and upon the type and capability of the electron source. The power capability ranges from milliwatts to peak values of hundreds of megawatts, and the frequency of operation ranges from zero to the order of 1 billion Hertz (gigahertz - GHz). The evacuated envelope may be glass, quartz, ceramic, or metal.

Electronic A-B Rolling (A/V, computer, M/M)
Editing of a master tape from two playback machines, one containing the A-roll and the other the B-roll. By routing the A and B playback machines through an electronic switcher, a variety of transition effects can be achieved for the final master tape. Also, the projection of SOF (sound on film) on one film chain (A-roll), with the silent film projected from the other island (B-roll). The films can be mixed through the switcher.

Electronic Circuit (computer, microelectronics)
Channel, route, path through which electron flow is directed to accomplish work. Used in digital devices, the circuit acts upon on/off pulses. In analog devices electronic circuits deal with vibrations called frequencies (radio, radar, earphones, television).

Electronic Countermeasures (communications, computer)
Techniques, devices, and equipment necessary for one adversary to deny or counteract an enemy's use of radar, communications, guidance, or other radio-wave devices. Because of the growing use of optical and infrared techniques for communications, guidance, detection, and control, electronic countermeasures (ECM) are sometimes called electromagnetic, rather than electronic countermeasures to convey more adequately the idea that countermeasures are not confined to the portion of the spectrum where electronic techniques alone are used, but may be utilised throughout the electromagnetic spectrum. Some of the newer weapons and applications disable soldiers on the battlefield until they can be captured – any personnel carriers (truck, tank) are not affected.

Electronic Data Interchange: EDI (communications, computer)
Set of standards by which companies can electronically exchange items such as invoices and purchase orders. EDI services enable users to interconnect regardless of the type of network or equipment being used, provided the same EDI standard is being supported.

Electronic Disk (computer)
Term sometimes used to describe internal, chip-based RAM (random access memory) that lets the computer regard part of its memory as another disk drive. It is also, sometimes called RAM disk, or a phantom disk.

Electronic Display (computer)
Electronic component used to convert electric signals into visual imagery in real time suitable for direct interpretation by an operator. It serves as the visual interface between human and machine. The visual imagery is processed, composed, and optimized for easy interpretation and minimum reading error. The electronic display is dynamic in that it presents information within a fraction of a second from the time received and continuously holds that information, using refresh or memory techniques, until new information is received. The image is created by electronically making a pattern from a visual contrast in brightness on the display surface without the aid of mechanical or moving parts. Types of displays include: cathode ray tubes (CRT); flat panel displays (light emitting diode, liquid crystal display); and projection displays.

Electronic Editing (A/V, production)
Joining of two shots on videotape without cutting the tape.

Electronic Equipment Grounding (computer, microelectronics)
Connecting equipment to an electromagnetic reference common to itself, its power source, its environment, and the environment of its users. Electronic equipment is grounded to protect users from shock, to protect the equipment from spurious current or voltages, and especially to isolate it from the electromagnetic "noise" level that contaminates its environment.

Electronic Field Production: EFP (A/V, production)
Television production activity outside the studio usually shot for postproduction (not live).

Electronic Funds Transfer Systems: EFT (communications, computer)
Computer information collection and telecommunications techniques that electronically transfer the movement of currency and funds between accounts managed by financial institutions: paying for goods and services by transferring the funds electronically.

Electronic Image Stabilization: EIS (A/V)
Feature in camcorders to compensate for camera movement. A servo mechanism, while using digital processing, "floats" the lens or picture to compensate for movement so that the operator can avoid, to a degree, recording shaky pictures (feature of "fuzzy logic").



Electronic Industries Association: EIA (A/V, communications, computer)
Membership organisation, founded in 1924, that includes manufacturers of electronic parts and systems. The EIA sets electrical and electronic interface standards, such as the EIA RS232-C interface between computers or terminal, and modems; RS-422, a more robust version of the RS-232-C standard: and RS 170-A, the consumer standard for connection of NTSC colour (National Television Standards Committee) television signals. The EIA/TIA 568A & B (ISO 8877) provide for the communications and cabling guidelines for Local Area Networking.

Electronic Industries Association of Japan: EIAJ (A/V, electronics)
EIAJ established the Type No. 1 Standard for 1/2 inch helical scan videotape recorders. The standard assures that any monochrome tape recorded on one such recorder can be played back on any other monochrome or color recorder, and any color tape can be played back on any other color VTR, provided it meets the EIAJ Type No.1 Standard.

Electronic Integrated Publishing: EIP (computer/printing)
Term that is sometimes used to describe the usage of computers in the publishing process, from concept through to the final, printed product.

Electronic Listening Devices (communications)
Devices which are used to capture the sound waves of conversation originating in an ostensibly private setting in a form, usually as a magnetic tape recording, which can be used against the target by adverse interests. These practices are unlawful in the United States and Canada except when carried out by law enforcement officers acting under authority of a warrant.

Electronic Mail: E-Mail (communications, computer)
In a communications network, the transmission and reception of messages analogous to traditional paper-based mail. Sending messages directly from one computer to another; the messages may be sent and stored for later retrieval.

Electronic News Gathering: ENG (A/V, production)
Utilising portable cameras, videotape recorders, lights, and sound equipment for the production of daily news stories and short documentaries. ENG is usually done for immediate post-production, but the capture can also be transmitted live from the field.

Electronic Power Supply (computer)
Source of electric energy employed to furnish the devices in an electronic circuit with the proper electric voltages and current for their operation. The more common sources of energy are chemical batteries, gel-cells, and alternating-current mains or lines. Batteries are useful as portable sources but have small capacities.

Electronic Publishing (computer)
Technology encompassing a variety of activities which contain or convey information with a high editorial and value-added content in a form other than print. Included in the list of presently practised electronic publishing activities are: on-line data bases, videotext, teletext, videotape cassettes, videodiscs, cable TV programming (direct broadcasting satellite delivery is optional), and electronic mail and messaging.

Electronic Spread Sheet (computer)
Computerized worksheet used to organize data into rows and columns for analysis.

Electronic Switch (computer, microelectronics)
Electronic device to which two input waveforms can be applied and which delivers, at a pair of output terminals, a signal that is alternately a replica of each of the input signals. The transmission gate performs the basic switching function of the electronic switch, and sometimes such a gate circuit is itself defined as an electronic switch.

Electronic Switcher (A/V)
Video switcher that uses active components, digital electronics, to affect signal routing.

Electronic View Finder: EVF (A/V)
Describes the tiny TV/monitor in the eyepiece of a camcorder (color or monochrome).

Electronics (computer, microelectronics)
Branch of science and technology relating to the conduction and control of electricity flowing through semiconducting materials or through vacuum or gases. Electronics is concerned with the study and applications of the motions of charge carriers (electrons, holes, and ions) under the influence of externally applied voltage or current, or in relation to the incidence or production of radiant energy.

Electro-optic: EO (computer, photonics)
Devices that use physical effects where electric fields influence optical properties of some crystals.

Electro-Optic Effect (computer, photonics)
Change of the refractive index of a crystal as a result of an applied electric field.

Electrophotographic (computer/printers/copiers)
Printing technique used in laser printers and copiers. A negative image made of dots of light is painted onto a photosensitive drum or belt that has been electrically charged. The light comes from a laser, LED, or liquid crystal shutters that function as gates. Wherever light is applied, the drum becomes uncharged. A toner (dry ink) is applied and it adheres to the charged areas of the drum. The drum transfers the toner to the paper, and pressure and heat fuse the toner and paper permanently. Some electro-photographic systems use a positive approach in which the toner is attracted to the laser produced latent image.

Electrostatic Focus (A/V)
One of two methods of focusing an electron beam, the other being electromagnetic. The electrostatic method uses electrically charged plates.

Electrostatic Lens (computer, microelectronics)
Electrostatic field with axial or plane symmetry which acts upon beams of charged particles of uniform velocity as glass lenses act on light beams. The action of electrostatic fields with axial symmetry is analogous to that of spherical glass lenses, whereas the action of electrostatic fields with plane symmetry is analogous to that of cylindrical glass lenses.

Electrostatic Plotter (computer/plotter)
Plotter that charges specialised paper as the paper passes a screen of electrodes: the toner is applied to the charged paper.



Electrostriction (A/V, microelectronics)
Form of elastic deformation of a dielectric induced by an electric field; specifically, the term applies to those components of strain which are independent of reversal of the field direction. Electrostriction is a property of all dielectrics and is distinguished from the converse piezoelectric effect, a field induced strain, which changes sign upon field reversal and which occurs only in piezoelectric materials. The electrostrictive effect in certain ceramics is employed for commercial purposes in electromechanical transducers for sonic and ultrasonic applications (i.e. microphones).

Elevator Seeking (communications/LANs, computer)
Process in which a file server determines the order for executing file requests based on the current location of the disk drive heads.

Ellipsoidal Spotlight (A/V, production)
Spotlight producing a very defined beam, which can be shaped further by metal shutters.

E-Mail: electronic mail (communications, computer)
Sending messages directly from one computer to another; the messages may be sent and stored for later retrieval.

Embedded Object (computer/Windows)
Presenting information in a document, created in another application. Information in the embedded object does not exist in another file outside of that document.

Embedded Command (computer)
Code that is embedded within a command to direct special effects within a text, page, document, or to direct a printer to change fonts, underline text, and other features.

Embedded Systems (computer)
Computer systems that can't be programmed by the user because they are preprogrammed for a specific task and are buried within the equipment they serve.

Emitter (computer/microelectronics)
Region of a transistor from which charge carriers are injected into the base.

EMS Memory (computer)
Type of expanded memory available on systems that conform to the Lotus-Intel-Microsoft Expanded Memory Specification (LIM EMS).

Emulation (computer)
Ability of one computer to interpret and execute the instruction set of another computer.

Emulation Mode (computer)
Mode in which a device such as a computer, printer, plotter, can imitate the behavior of a different device (see terminal emulation).

Emulator (communications, computer)
Device that is built to work like another. A computer can be designed to emulate another computer and to execute software that was written to run in the other machine. A terminal can be designed to emulate various communications protocols and hook into different networks. The emulator can be hardware, software, or both.

Emulsion (A/V, printing)
In photograph processes, the photosensitive coating on the film.

Enable (computer)
Condition which permits a specific information processing event to take place.

Enabled (computer)
Capability of a control object to respond to user actions expressed as true or false.

Encapsulate (computer/microelectronics)
To embed electronic components in a protective coating, when the plastic encapsulant is in a fluid state so that it will set in solid form as an envelope around the device.

Encapsulated PostScript File: EPS (computer/Windows)
File that prints at the highest possible resolution for the attached printer. An EPS file may print faster than other graphical representations. Some Windows graphical applications can import EPS files. EPS files describe an image in Adobe Corporation's Postscript page-description language and usually incorporate a TIFF bit-mapped image in the header of the file, so a representation of the EPS image can be displayed. Some applications provide a Windows Meta File (WMF) header to be compatible with OLE 1.0 applications (see PostScript and WMF).

Encapsulation (communications, computer)
Addition of control information by a protocol entity to data obtained from a protocol user.
In communications cabling, outside plant construction, an encapsulation can refer to a splice point or connection point that has been established prior to underground burial of the cable plant, thus facilitating future additions and modifications to the cabling plant by digging up the "encapsulation" and accessing the cabling distribution point. It can often substitute for having to install an above-ground pedestal for housing the cable, where the location of an above-ground pedestal may not be practical, or aesthetically feasible.

Encoder (A/V, microelectronics)
Electronic circuitry that combines primary RGB (red, green, blue) signals into composite colour video signals according to a particular country's television standard.

Encryption (communications, computer)
Encoding of data for security by converting the standard data code into a proprietary code. The encrypted data must be decoded in order to be used. Encryption is used to transmit documents over a network or to encode text so that it cannot be changed.

END (computer)
Point in a program where all functions have been processed by the computer.

End Key (computer)
Key on a computer's keyboard that is marked "end" and that can be used to move the cursor to the bottom of the screen or file, or to the next word or to the end of line.

End Of File (computer)
Point in a program or module where all files have been read by the computer.

Endless Loop (A/V, computer)
In audio/visual terminology, a tape that is made up to run continuously with pre-programmed information so that when the tape reaches its end, it automatically re-winds and starts over again. In computer terminology, a series of instructions that are continuously repeated; this can be caused by a program error, or it can be a desired program function to repeat information on a screen, for continuous running ( a repeating animation on a screen saver is an example).

End Mark (computer)
Symbol used by some word processor applications to indicate the end of a document.

End Points (computer)
Two ends of a line, the vector point: for two dimensions, each end point has 2 coordinates (x, y plane); for 3-D graphics, each has 3 coordinates (x, y, z plane).

End To End Connectivity (communications, computer)
One of four founding principles of the Universal Communications System that can be installed within a workgroup, on a floor, or for a building communications infrastructure. End-to-End Connectivity means that any user, at any communications outlet, can be both physically and logically connected to any other user, at any other outlet, at any time.

End User (communications, computer)
Individual who acquires and uses computer hardware, software, or applications.

ENG: Electronic News Gathering (A/V, production)
Use of portable cameras, videotape recorders, lights, and sound equipment for the production of daily news stories and short documentaries. ENG is usually done for immediate post-production, but the capture can also be transmitted live from the field.

ENG/EFP Cameras (A/V, production)
Electronic news gathering or electronic field production cameras. Replacing film cameras for news reporting, these cameras are portable, self-contained, and largely automated.

Engraving (A/V)
Musical term meaning a musical score printed in a professional manner. High quality, musical printing programs are referred to as engraving applications.

Enhancer (A/V)
Circuit component that can improve video quality by boosting the high-frequency content of the video signal. Enhancers are built into a VCR or sold as a separate accessory.

Enhanced Keyboard (computer)
Keyboard layout first introduced by IBM Corp., that supersedes earlier PC and PC/AT keyboard layouts. Additional function keys and layouts were added along with additional Ctrl, and Alt key positions and the backspace key was restored to its full size. It has a separate group of cursor movement keys located to the right of the original group.

Enhancement (computer)
Revision of a software program or an application program that may not be a full, new revision, but that has some enhanced features over an earlier version. Hardware enhancements could include a higher resolution monitor, but not new monitor technology.

ENIAC (computer)
Electronic Numerical Integrator and Computer: developed at the Moore School of the University of Pennsylvania in Philadelphia between 1943 and 1946, it was the first electronic automatic computer, and it became a landmark leading to the development of many automatic computer designs. The logical design of the system was based on the ideas of Dr. John Mauchly, and credit for engineering goes to J. Presper Eckert, Jr.

Enter Key (computer)
Large rectangular or reverse L shaped key that provides the "enter" command, or that acts the same as a carriage return key on a typewriter keyboard: it inserts a hard return into a text document (embedded code).

Entrapment (computer/microelectronics)
In fabrication and manufacturing, the damaging admission and trapping of air, flux, and fumes, caused by contamination and plating process defects.

Entry (computer)
Input of information, data, or commands into an application that can also be seen on the screen/monitor (such as text entry).

Entry Level (computer)
Term used to describe an application or component having fewer features than a professional version but easier for a beginner to use.

Entry Mode (computer)
Spreadsheet application mode that lets the user enter data.

Entry Point (computer)
Point in a module where control is transferred. Each module has only one entry point.

Envelope (A/V, communications, computer)
Graphic description of the change of a sound's characteristic over time. An envelope is created by an electronic device called an envelope generator. An amplitude or volume envelope describes the intensity of the sound from beginning to end. In communications, it can be a range of frequencies: in computing terms, it can be a group of bits, bytes, or information treated as a single item, or unit.

Environment (computer/DOS/Windows)
Combination of computer hardware, operating system, and user interface.

Environmental Variable (computer/DOS/Windows)
DOS term for variables that are declared by PATH and SET statements, usually made in an AUTOEXEC.BAT file, and stored in a reserved memory location by DOS. These variables may be used by applications to adjust the operation for compatibility with user-specific hardware elements or directory structures.

EOF: End Of File (computer)
Point in a program or module where all files have been read by the computer.


EP: Extended Play (A/V)
Slowest record/play speed for VHS VCRs. EP also has the poorest picture quality: also known as SLP (Super Long Play).

Epitaxial (computer/microelectronics)
Pertaining to a single crystal layer on a crystalline substrate, and having the same crystalline orientation as the substrate: for example, silicon atoms condensed from vapor, phased onto a silicon-wafer substrate.

Epitaxial Growth (computer/microelectronics)
Process of growing layers of material on a selected substrate. Usually silicon is grown in a silicon substrate. Silicon and other semiconductor material may be grown on a substrate with compatible crystallography, such as sapphire (silicon-on-sapphire).

Epitaxial Layer (computer/microelectronics)
Precisely doped, thin layer of silicon grown on a p-doped thick wafer and into which n-type semiconductor junctions are diffused.

EPROM (computer)
Erasable Programmable Read Only Memory Chips: reusable PROM chips that hold their memory content until erased under ultraviolet light.

EPS (computer)
Encapsulated PostScript: also used as the extension for these files. EPS files describe an image in Adobe PostScript page-description language and usually incorporate a TIFF bit-mapped image in the header of the file, so a representation of the EPS image can be displayed. Some applications provide a Windows Meta File (WMF) header to be compatible with OLE 1.0 applications.

EPT Port (computer)
Unique port on a computer requiring a special card and special software. Only certain printers, such as the IBM Personal Pageprinter, for example, use this port.

Equal To (=) Condition (computer)
Logical operation in which the computer compares two numbers to determine equality.

Equalization (A/V, computer, M/M)
In audio/video production, controlling the audio and/or video signal by emphasizing certain frequencies and eliminating others. Equalization can be accomplished through an equalizer either manually or automatically.

Equalizing Pulses (A/V)
In Television production electronics, Pulses on one-half the width of the horizontal sync pulses transmitted at twice the rate of the horizontal sync pulses during the portions of the vertical blanking interval immediately preceding and following the vertical sync pulse. These pulses cause the vertical deflection to start at the same time in each interval, and also keep the horizontal sweep circuits in step during the portions of the vertical blanking interval immediately preceding & following vertical sync pulse. The Equalizing Pulses synchronize the interface of horizontal lines.



Equivalent Circuit (computer, microelectronics)
Representation of an actual electric circuit or device by a simplified circuit whose behaviour is identical to that of the actual circuit or device over a stated range of operating conditions. These conditions depend on the elements contained in the actual circuit and may include such variables as frequency, temperature, and pressure, in addition to voltage and current. Equivalent circuits are often used to simplify circuit analysis since they can illustrate the relation between the variables more clearly than the actual circuit.

Erasable Optical Disc (computer, M/M)
Optical disc where data is stored, moved, changed, and erased similar to magnetic media.

Erase Head (A/V, computer)
Head in a magnetic tape unit that erases any information previously recorded on the tape.

Erase Tab (A/V)
Small, plastic flap on the rear edge of a video cassette that can be removed to prevent accidental erasure of the cassette tape contents (prevents re-recording on the tape).

Ergonomics (computer)
Science of people-machine relationships. An ergonomically-designed product implies that the device blends smoothly with a person's body or actions: the advanced study of human factors relating to computers.

Erlang, A.K. (Agner Krarup, Denmark) (mathematics)
(1878-1929) A Danish mathematician. Erlang the language and unit were named after him. Interested in the theory of probability, in 1908 Erlang joined the Copenhagen Telephone Company where he studied the problem of waiting times for telephone calls. He worked out how to calculate the fraction of callers who must wait due to all the lines of an exchange being in use. His formula for loss and waiting time was published in 1917. It is now known as the "Erlang formula" and is still in use today.

Erlang (historic/communications/telephone)
Older, analog based, unit of traffic used to specify total capacity or average use of a traditional Telephone System. One Erlang was equal to the continuous usage of a telephone line. Traffic in Erlangs was the sum of holding times of all lines, divided by the period of measurement.

Error Analysis (computer)
Analysis of the basic arithmetic operations of digital computers that are not exact but are subject to rounding or truncating errors (the cumulative effect of these errors).

Error Correction Code: ECC (communications, computer)
Coding system that, in conjunction with an Error Detection Coding scheme, can reconstruct erroneous data to its original value. In algebraic correction, a parity check is assigned to positions in the code. In geometric correction, if an error is detected, the distance between two messages must be at least two for every pair of messages: otherwise, there would be a message that a single error would carry over into another acceptable message, and that error could not be detected.

Error Detection Code: EDC (communications, computer)
Coding system that can detect errors in a single byte or in blocks of data. Single byte errors are caught by parity checkers such as the one employed in the PC's memory system. Errors in blocks of data are commonly determined by using techniques such as Cyclic Redundancy Check codes (CRC) for data transfer by modem. More sophisticated EDC methods are employed when error correction is required, such as with CD-ROMs.

Error Rate (communications, computer)
Ratio of the number of data units in error to the total number of data units.


Error Trapping (computer/Windows)
Procedure by which errors generated during execution of applications are re-routed to a group of code lines called "error handlers". These lines perform a predefined operation, such as ignoring the error. In Windows, if errors are not trapped in Visual Basic, the standard message dialog box, with the text message for the error that occurred, will appear.

Escape Key (computer)
Usually at the topmost left row on the keyboard, slightly separated from the first function key (F1), it is used to exit an application program or function.

ESF Format: Extended SuperFrame (communications)
In communications, a T1 level format that has been improved to allow line monitoring while the line is being used in normal operation. ESF utilizes 24 frames (rather than the 12 frame D4) and provides room for error detection and correction through Cyclic Redundancy Check (CRC) bits and other commands that are used for diagnostic purposes.

Essential Area (A/V, production)
Section of the television picture, centered within the scanning area, that is seen by the home viewer, regardless of masking of the set or slight misalignment of the receiver. This is sometimes called the "critical area".

ESS# (3,4,5,6 etc.): Electronic Switching System (communications, computer)
Systems from AT&T that are large and used in metropolitan areas to switch very large banks of circuits for voice and data communications: Central Office Switching Systems.

Establishing Shot (A/V, production)
Segment designed to orient the viewer by shooting the story's location or time-line, or the surroundings within which the story happened or is happening (see cover shot).

Etch Factor (computer/microelectronics)
In microelectronics fabrication, the ratio of depth of etching to the amount of the undercut.

Ethernet (communications, computer)
Original Local Area Network developed by Xerox, Digital, and Intel that interconnected personal computers via coaxial cable by running the cable around the office. It uses the CSMA/CD access method and transmits at 10 megabits per second. Fast Ethernet transmits at 100 megabits per second. Gigabit Ethernet transmits at 1,000 megabits per second. Ethernet uses a bus topology that can connect up to 1,024 personal computers and workstations within each main location, however, it is recommended that 1,000 workstations be divided up amongst several Local Area Network segments (i.e. 100 PCs each). From each 100 workstations an intelligent ‘HUB” can be installed that is then connected to 10 other intelligent hubs. This type of implementation is called “Switched Ethernet” and it imposes some hierarchy into the topology and configuration (rather than just a ‘flat’ LAN without hubs). This introduction of a hierarchy allows for each of the 100 workstations attached to each hub to run at 10 or 100 megabits per second, and then connect to the other 9 hubs at 1 Gigabit per second (Gigabit Ethernet) using a fibre optic backbone to connect all 10 hubs. Ethernet has evolved into the IEEE 802.3 standard. Over 90% of all Ethernet type LANs are being implemented with Twisted Pair Cabling rather than coaxial cable – and with fibre optic backbone cabling, wherever a Switched Ethernet implementation is installed..


E Time (computer)
Term sometimes used to describe the execution portion of the computer machine cycle.

European Broadcast Union: EBU (A/V, communications)
Organization establishing audio and video standards for Western Europe. EBU performs functions similar to those of the NTSC and AES in the United States. The EBU is affiliated with DIN and CCITT (see AES, CCITT, NTSC).

Evaporation Sources (computer/microelectronics)
Containers used as heat sources for vacuum evaporation of thin film layers on substrates. The process is frequently employed by resistively heating the evaporant in a ceramic crucible or by self-heating containers constructed of tungsten, molybdenum, or tantalum.

Evaporation/Sputtering Materials (computer/microelectronics)
Metals used for evaporation charges and sputtering targets: to allow for chromium and its alloys for applying a thin adhesive layer on integrated circuit substrates to allow better deposition of gold or other metal; to allow for resistor material; to allow for vacuum deposition in mask production. Other materials include aluminium and aluminium alloys, for first layer deposition in metal oxide semiconduction (MOS) technology; to allow for molybdenum, as a conductor or adhesive layer for IC fabrication; titanium, as an intermediate adhesive layer for beam-lead interconnection.

Event (A/V, communications, computer/Windows)
In Audio/Visual terms, Event is sometimes used to describe the capacity of a VCR's (video cassette recorder) timer. One event consists of turning on the VCR at a specified time, recording from a designated channel, and then turning off after a pre-set duration.

In computing terms, the occurrence of an action resulting in a Windows message. Events are usually related to mouse movements and keyboard actions. Events can also be generated by other external hardware devices, such as MIDI sequencers or communications modems. In Windows Network Operating Systems, an Event is any significant occurrence in the system or in an application that requires users to be notified, or an entry to be added to a log.

Event Driven (computer)
Property of an operating system or environment implying the existence of an idle loop. When an event occurs, the idle loop is exited, and the event handler code, specific to the event, is executed. After the event handler has completed its operation, program execution returns to the idle loop, where it awaits the next event. In multiprogramming environments, programs share resources based on events that take place in the programs.

Event Handler (computer)
Block of program code invoked upon the occurrence of a specific event.

Event Log Services (computer/Windows)
Records events in the system, security, and application logs.

EVF: Electronic View Finder (A/V)
Describes the tiny TV/monitor in the eyepiece of a camcorder (colour or monochrome).



Exception Reporting (computer)
Technique for screening large amounts of computerized information in order to prepare and process, or print reports containing only that information requiring action. Exception reports present a user with concise information needed for specific actions: they can be reports that show only information reflecting unusual circumstances.

EXE (computer/DOS)
File extension that was used that could be loaded and run by the computer (see executable).

EXE2BIN (computer/DOS/Programmer)
DOS Command that converted executable files with a .EXE extension to binary files with a .BIN extension. This command was intended for programmers and was only used if the users were writing their own program or creating specific instructions to use it.

Executable (computer/Windows)
Code, usually in the form of a disk file, that can be run by the current operating system to perform a particular set of functions. Executable files in Windows carry the extension EXE and may obtain assistance from dynamic link libraries (DLLs) in performing tasks.

Executable File (computer, DOS/Windows)
File used to start a program. In Windows. It must have the extension BAT, COM, EXE, or PIF.

Executable Statement (computer)
Procedural step in programming which calls for processing action by the computer, such as performing arithmetic, reading data from an external medium (disk, tape, etc.), making a decision. They must be distinguished from non-executable, or declarative statements providing information about the nature of the data or about the way the processing is to be done without themselves causing any processing action. Executable statements are sometimes called imperative statements because their form often closely resembles that of an imperative sentence in a natural language.

Execute (computer)
Perform a specified computer instruction, or to run a computer program.

Excitation Potential (computer, microelectronics)
Difference in potential between an excited atomic or molecular state and the ground state. The term is most generally used in connection with electron excitation, but it can be applied to excited molecular vibration and rotation rates.

Exclusive Application (computer/Windows)
Application that has sole use of the computer's resources while it is running in the foreground mode. When an exclusive application is running in a window, it gets most, but not all, of the computer's resources.

Exit (computer/DOS)
DOS Command that exits the current COMMAND.COM processor or another command processor, and returns to the next previous command processor. EXIT is only used when multiple processors are loaded. This command also returns the user to applications (word processing, database, spreadsheet, etc.), that provide a temporary exit to DOS. If DOS cannot leave the current command processor, the EXIT command is ignored.

Exit Point (computer)
Point in a module where control is transferred. Each module has only one exit point.

Expand (computer/Windows)
Show currently hidden levels in the Directory Tree. With File Manager, the user can expand a single directory level, one branch of the tree, or all branches at once.

Expanded Memory Emulator (computer/DOS)
Device driver that allowed extended memory on 80386 computers, and 80486 computers to behave like expanded memory.

Expanded Memory Manager: EMM (computer/DOS)
Device driver that allowed a computer to use expanded memory.

Expanded Memory Specification: EMS (computer)
Type of expanded memory available on systems that conformed to the Lotus-Intel-Microsoft Expanded Memory Specification (LIM EMS).

Expander (A/V, computer, M/M)
Musical synthesizer without a keyboard. An expander is usually provided in a rack-mountable enclosure. Expanders are universally controlled by MIDI messages.

Expansion Slots (computer)
Slots inside a computer that allow a user to insert additional circuit boards.

Expert Shell (computer)
Software application having the basic structure to find answers to questions; the questions themselves can be added by the user.

Expert System (computer)
Methods and techniques for constructing human/machine systems with specialized problem-solving expertise. It emphasizes the knowledge that underlies human expertise and has simultaneously decreased the apparent significance of domain-independent problem solving theory. In fact, a new set of principles, tools, and techniques have emerged that form the basis of knowledge systems. This expertise consists of knowledge about a particular domain, understanding of domain problems, and skill at solving them. For inexpensive personal computing enjoyment, a simplified application package that presents the computer as an expert on some topic (history, games, medicine, sports, etc.).

Exploded Pie Chart (computer)
Pie Chart with a "slice" that is separated from the rest of the chart.

Exponent (computer, mathematics)
Second element of a number expressed in scientific notation. The exponent is the power of 10 by which the first element, the mantissa, is multiplied to obtain the actual number. For +123E3 the exponent is 3. Multiply 1.23 by 1,000 (10 to the third power) to obtain the result: 1,230.

Exposure (computer/microelectronics)
Subjecting photosensitive matter to radiant energy such as light to produce an image.

Export Path (computer/Windows)
In directory replication, a path from which subdirectories, and the files in those subdirectories, are automatically exported from an export server (see directory).

Export Server (computer/Windows)
In directory replication, a server from which a master set of directories is exported to specified servers or PCs (import computers), in the same or other domains (see directory replication).

Expression (computer term)
Combination of variable names, values, functions, operators returning a result, usually assigned to a variable name. A function may be used in an expression, the expression may return the value determined by the function to the same variable as the argument. An expression-oriented language is one in which expressions may stand alone such that, when encountered during program flow, their value is calculated and printed immediately.

Extend Selection (computer/Windows)
Select more than one object. For example, a user can select a group of files to be moved or copied with File Manager.

Extended ASCII (communications, computer)
The second half of the ASCII character set (characters 128 through 255). The symbols are defined for the Personal Computer by different vendors for different, proprietary uses.

Extended Definition Beta: Ed Beta (A/V)
Better version of the old Beta format from Sony Corp., that had better horizontal resolution: somewhat similar to S-VHS.

Extended Memory Manager (computer/DOS/Windows)
Device Driver that allowed the computer to use extended memory. The Windows extended memory manager was HIMEM.SYS.

Extended Partition (computer/Windows)
Created from free space on a hard disk, it can be sub-partitioned into zero or more logical drives. Only one of the four partitions allowed per physical disk can be an extended partition, and no primary partition needs to be present to create an extended partition.

Extended Play: EP (A/V)
Slowest record/play speed for VHS VCRs. EP also has the poorest picture quality. Also known as SLP (Super Long Play).

Extended SuperFrame (communications)
In communications, a T1 level format that has been improved to allow line monitoring while the line is being used in normal operation. ESF utilizes 24 frames (rather than the 12-frame D4) and provides room for error detection and correction through Cyclic Redundancy Check (CRC) bits and other commands that are used for diagnostic purposes.

Extended Synthesizer Standard (A/V, computer)
Recommended sound synthesis capability of an MPC-compliant audio-adapter card. The extended synthesizer standard was established by the MPC specification 1.0 issued by the Multimedia Marketing Council. The extended requirement is that a least nine melodic timbres assigned to channels 1 through 9 and 16 percussive timbres assigned to channel 10 be playable simultaneously.

Extended VGA (computer)
Description of older graphic adapter cards that displayed 800 x 600 pixels with 256 colours.

Extension (computer/DOS/Windows)
Period and up to 3 characters at end of a filename. An extension can indicate the type of file or directory. For example, documents created with Microsoft Word have the extension .doc.

External Command (computer/DOS/Windows)
Command that is stored in its own file and loaded from disk when it is invoked: Commands that access DOS programs residing on the DOS disk as program files. The programs must be read from the disk before they can be executed: they are not automatically loaded when the computer is turned on (see internal DOS command).

External Direct-Connect Modem (communications, computer)
Modem separate from the computer, allowing it to be used with a variety of computers.

External Interrupt (computer)
Interruption that occurs due to operator/user intervention, or by a sensor device, another monitoring device, or by another computer system.

External Key (A/V, production)
Cutout portion of the base picture filled by the signal from an external source, such as a third camera (first camera providing the base picture, the second camera the key signal).

Extrinsic Properties (computer/microelectronics)
Properties introduced into a semiconductor by impurities within a crystal.

External Sorting (computing)
Sorting routine that is performed using an external disk or tape drive as a temporary storage and sorting work area during the sorting process.

External Storage (computer)
Off-Line, external location for storing information, removed from the computer source, either magnetic or optical disk, or magnetic tape format, that can be archived, on a shelf, in a vault or other storage facility, for backup and safekeeping.

Extrinsic Semiconductor (computer/microelectronics)
Resulting semiconductor produced when impurities are introduced into an otherwise non-semiconductor crystal. The electrical properties depend upon the impurities.

Eyewash (A/V, production)
File (library) videotape of generic shots, pictures, that can be used to cover a current story, for example, hardware racks and rows (to be inserted in a story about hardware costs), snow being piled up by bulldozers (to be inserted in a story about winter). This can also be called archive or "in the can" (already produced) files.