T

Table Lookup (computer)
Term used to describe looking up or searching for some information in a table, required for many programming applications for writing compilers and interpreters. Table manipulation, search techniques, and routines should be considered, developed, cataloged at all computer installations because of their usefulness. The definitions that are promulgated by the American National Standards Institute (ANSI) in Vocabulary for Information Processing include the following:

Field: Specific area of a record used for a particular category of data;
File: Collection of related records that must be processed in the same way;
Key: Particular field of a record on which the processing is performed;
Position: Logical location of a record in a table.
Record: Logical unit of information that my contain one or more fields;
Table: Collection of records containing control information to be used repeatedly;

Tab Order (computer/Windows, M/M)
Order in which the focus is assigned to multiple control objects within a Windows dialog box by successive depressions of the Tab key. the term has carried over into interactive multimedia to indicate the default sequence of selections in a single image.

Take (A/V)
In audio/visual production, a signal for a cut from one video source to another. Also, a take can mean any one of similar repeated shots taken during videotaping and filming. Sometimes take is used synonymously with shot. A good take is the successful completion of a shot, a show segment, or the videotaping of the whole shot. A bad take is an unsuccessful recording; another take is then required until a good take occurs.

Takeup Reel (A/V)
Reel that takes up film or tape from the supply reel. It must be the same size as the supply reel in order to maintain proper tension.

Taking Lens (A/V)
In audio/visual production, a term used to describe the on-the-air lens: refers to the lens on turret cameras that is actually relaying the scene to the camera pickup.

Talent (A/V)
In audio/visual a term used to describe the collective name for all performers and actors who appear regularly on television.

Tally Light (A/V)
In audio/visual production, the red light on a camera and inside the camera viewfinder, indicating when the camera is the live camera; the camera that is on the air.

Tank Circuit (communications, microelectronics)
Inductor and capacitor in parallel. The term is often used to denote the parallel resonant circuit in the output state of a radio transmitter, but it has been applied to any parallel resonant circuit. In many cases, the inductance in the tank circuit is one winding of a two-winding, air-core transformer. The secondary is connected to some load, such as an antenna. Power is delivered from the source to the load through the tank circuit, with an effort usually made to adjust the parameters for maximum power transfer. Since the tank circuit is a parallel resonant circuit, the parameters can be chosen so that, at a desired frequency, the voltage across the tank circuit maximizes. In radio transmitters this is accomplished by varying the capacitance, but in other situations, like oscillators, the inductance may be varied by means of a tuning slug in the coil.

Tape (A/V)
In audio/visual terms, acetate ribbon approximately one thousandth of an inch thick, varying in width from an eighth of an inch to 2 inches and coated with iron oxide (the dull side) used to record magnetic impulses from audio and video sources.

Tape Backup (communications, computer)
Use of magnetic tape for storing duplicate copies of hard disk files. Quarter-Inch cassettes are the common tape backup on personal computers. Digital Audio Tape (DAT) that uses 4mm cassettes holding 1 GigaByte of data is a standard.

Tape Drive (computer)
Drive(s) on which reels of magnetic tape are mounted when the data contained on the tape is ready to be read and processed by the computer system.

Tape Label (computer)
Term used to describe magnetic tape labels: special records appearing at the beginning and end of a reel of magnetic tape providing details about the file of records stored.

Taper Testers (computer/microelectronics)
In microelectronics fabrication terminology, a method used to test one aspect of the dimensional integrity of wafers (slices of semiconductor material): taper results when the two faces of the wafer, under test, are not in parallel.

Target (A/V, computer/DOS/Windows)
In DOS/Windows, disk or directory to which a user can copy or move one or more files.

In audio/visual terms, the light sensitive front surface of a camera pickup tube which is scanned by an electron beam.

Tariff (communications)
Rate structure established by the communications common carries and approved by federal communications authority for voice, data, and video communications.

Task (computer)
Term used to describe a unit of activity in a computer system. It is specified in terms of its external characteristics only, its internal structure and operation being unspecified. The external characteristics of a task that may be specified will depend on the context in which a task is being studied or controlled: these include; input and output parameters or variables; resource requirements; and execution time. A task is said to be uninterpreted if its function or operation is unspecified. If a system must preempt resources from a task at a certain point in its execution it is sometimes called the task, or state vector. A multitask system is one in which two or more tasks can be in progress at any given time.

Task (computer/Windows)
In Windows, an open application, when a user is utilizing Windows, Task Manager.

Task List (computer/Windows Networking)

Window that shows all running applications and enables switching between them. Task List is opened by choosing Switch To from the Control menu or by pressing CTRL+ESC.

T-Carrier (communications)
Digital transmission service from a common carrier or telephone company. Introduced by AT&T in 1983 as a voice transmission service, its use for data transmission has grown steadily.

T-carrier service requires multiplexers at both ends that merge the various signals together for transmission and split them at the destination. Multiplexers can analyze the traffic load and vary the speeds of the channels for optimum transmission.

T1 is a 1.544 megabit T-carrier channel that can handle 24 voice or data channels at 64 kilobits per second. The standard T1 frame is 193 bits long, which holds 24, 8-bit voice samples and one synchronization bit: 8,000 frames are transmitted per second.

T2 is a 6.312 megabit T-carrier that can handle 96 voice or data channels at 64 kbits/sec.

T3 is a 44.736 Mbit T-carrier that can handle 672 voice/data channels at 64 kbits/sec. T3 Carrier Channels generally require optical fiber cable medium.

TCP/IP (communications)
Transmission Control Protocol/Internet Protocol - a set of communications protocols developed by the Department of Defence, Defence Advanced Research Projects Agency (DARPA) to internetwork dissimilar systems. It is used by many corporations and almost all American universities and federal organizations. The File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP) provide file transfer and e-mail capability. The TELNET protocol provides a terminal emulation capability that allows a user to interact with any other type of computer in the network. TCP protocol controls the transfer, and IP protocol provides the routing mechanism.

TCR (computer/microelectronics)
Abbreviation for Temperature Coefficient of Resistance: the amount of change in the resistance of a material per degree of temperature rise.

TDM (communications)
Time Division Multiplexing - technique mixing several low-speed signals into one high-speed transmission. If A, B, & C are 3 digital signals of 1,000 bps each, they are interwoven into one 3,000 bps: AABBCCAABBCCAABBCC. At the receiving end, the different signals are divided out and merged back into single streams.

TDM Bus Switching (communications)
Form of time division switching in which time slots are used to transfer information over a shared bus between transmitter and receiver.

Teaser (A/V)
In audio/visual production, a term used to describe a headline or other brief reference to an upcoming news story, purposely vague and designed to arouse viewer anticipation.

Telco (communications)
Telephone Company - a company that provides telephone services.

Telecine (A/V)
The location where film islands operate. The term comes from television and cinematography. Occasionally, the telecine is used for film storage and some minor film editing jobs.

Telecine Chain (A/V)
Also called a Film Chain, or Film Island, or simply Telecine, it consists of one or two film projectors, a slide projector, a multiplexer, and a television film camera, or telecine camera. The word telecine originates from television and cinematography. Occasionally, the telecine is used for film storage and some minor film editing jobs.

Teleconferencing (communications)
Setup of a network for holding personal as well as group conferences between interested groups that are geographically dispersed over a large area.

Telecommunications
Communications, in modern terms, of all forms of information: voice, data, video. Historically, this term was more narrowly defined for voice communications (telephone).

Teleconferencing (A/V, communications, computer, M/M)
Audio conferencing is a conference among users provided internally by an organization's PBX and externally by telephone companies. Computer teleconferencing is a keyboard conference among users at their terminals or personal computers that is provided by software for bulletin boards. Video conferencing is a conference among several users that is provided by video cameras and monitors set up in the user's premises or in a public conferencing center. Video conferencing requires its own communications network that uses coaxial cable, optical fibers, microwave or satellite transmission, since conventional computer and voice networks may be too slow. Video conferencing is very slowly being integrated into data networks. In time all digital networks will provide intergrated voice, data, & real-time video, on demand.

Telematics (communications)
Term used sometimes in the time-shared industry to describe user-oriented information transmission services (teletex, videotex, store-and-forward telex, facsimile, etc.).

Telemetry (communications)
Transmitting data sensed by instrumentation/measuring devices to a remote station where it is recorded/analyzed. Data from a weather satellite is telemetered to the earth.

Telephone (communications)
Telephone (the term itself) formerly referred to the receiver, the instrument originally invented by Alexander Graham Bell; it is now commonly applied to the telephone set, which includes a transmitter, and an electronic network in addition to the receiver. The transmitter and receiver are housed together in a handset. A cord connects the electrical components of the handset to the electronic network within the telephone set. The transmitter is a transducer which converts acoustical energy into electrical energy. In most transmitters an electric current is modulated by the variations in contact resistances of organic granules or tiny beads (carbon, or carbon-based). Sound waves impinge on the diaphragm of the transmitter, causing the organic granules to move closer together, making more contact and decreasing resistance, or to move further apart, making fewer contact and higher resistance. The transmitter has a frequency-response range from 250 to 5,000 hertz (Hz). The frequency response rises uniformly to a broad maximum in the region of 2,500 Hz. Because of these characteristic and those of the telephone receiver, the speech heard by the listener resembles closely that of direct mouth-to-ear speech as heard by a listener a few feet from the person speaking. The receiver transducer operates on the relatively low power used in the telephone circuit to convert electric energy into acoustical energy. Unlike a loudspeaker, the telephone receiver is designed for close coupling to the ear. The telephone receiver has an approximate impedance of 150 ohms at a frequency of 1,000 Hz. The relationship of the acoustic and electrical elements produces a desired response-frequency characteristic. In addition to the basic components, the telephone set has a switch hook to connect it to the line and operate other associated features, a tone generator (older units have a rotary dial) which produces a range of dc pulses to actuate the switching gear in the telephone common carrier systems, and a ringer with an adjustable volume control, used to signal that a call is incoming.

Telephoto Lens (A/V)
In audio/video production, the same as long-focal-length lens: provides a closeup view of an event relatively far way from the camera.

Teleprocessing Systems (communications, computer)
Original term (older term) used to describe remote-terminal processing systems: they referred to a form of information processing in which remote terminals access a computer through some type of communication line. Some of those original applications include: (1) inquiry and response systems; (2) data collection systems; (3) data distribution systems; (3) conversational systems; (4) remote batch-processing systems.

Teleprompter (A/V)
In audio/video production, a mechanical prompting device that projects the moving copy over the lens, so that it can be read by the newscaster, or presenter, without losing eye contact with the camera lens (and subsequently, the viewer).

Teletext (communications)

One-way information retrieval services: a fixed number of information pages are repeatedly broadcast on unused portions of a TV channel bandwidth: a decoder at the television set (black box, usually rented) is used to select and display the pages.

Television (A/V, communications)
Electrical transmission and reception of transient visual images. Like motion pictures, television consists of a series of successive images, which are registered on the viewer, as a continuous picture because of the persistence of vision. Each visual image impressed on the eye persists for a fraction of a second. In television in the United States and Canada, 30 complete pictures are transmitted each second, which, with the use of interlaced scanning is fast enough to avoid evident flicker. At the television transmitter, minute portions of a scene are sampled individually for brightness (and color for color television), and the information for each portion is transmitted consecutively. At the receiver, each portion is reproduced in its proper position and with correct brightness (and color) to reproduce the original field, frame, or scene. The scene is focused on a photoelectric device within the camera, itself. Each portion of the screen is changed by the photoelectrons to a degree depending upon the brightness and color of the particular portion. The screen is scanned by an electron beam just as a reader scans a page of printed type, character by character, line by line. When so scanned, an electric current flows with an instantaneous magnitude proportional to the brightness and color of the portion scanned. Variations in this current are transmitted to the receiver, where the process is reversed. An electron beam in the picture tube is varied in intensity (modulated) by the incoming signals as it scans the picture-tube screen in synchronism with the scanning at the transmitter. The photoelectric surface of the picture tube produces light and color in proportion to the intensity of the electron beam which strikes it. Portions of the original scene are re-created in proper position, brightness, color.

Television Camera (A/V)
Electrooptical system used to pick up and convert a visual image or scene into an electrical signal called video. The video may be transmitted by cable to a suitable receiver or monitor some distance from the actual scene. A television camera may fall within one of several categories: studio, portable, or telecine. It may also be one of several highly specialized cameras used for remote viewing of inaccessible places such as the ocean bottom, in outer space, or inside nuclear power reactors. Modern cameras can be entirely solid stage devices. A television camera may be one-piece, with all components contained in one assembly, or it may consist of a head and a camera control unit (CCU) connected by a multiple-conductor cable, and be called a camera chain. The head unit comprises the optical system with lens, the picture pickup electronics, and a minimum of electronics necessary to generate and amplify the minute signals from the pickup electronics (tubes or solid-state charge-coupled devices). The CCU may contain electronics and controls which allow a skilled operator to adjust brightness (luminance), color (balance, saturation, and hue), and correction circuits (registration, gamma, and aperture) which improve the picture.

Television Receiver (A/V)
Equipment used to receive the transmitted, modulated, radio-frequency signals and produce synchronized visual images and sound for communications, education, and entertainment. The radio-frequency portion operates on the superheterodyne principle.

Television Scanning (A/V)
Process of scrutinizing the brightness of each element of detail contained in the image of a scene to be transmitted. In color television, the brightness variations of each scene are first separated by red, green and blue filters, after which the conversion from brightness to voltage on a time basis occurs separately for each of the three colors. Scanning also takes place in the receiver in exact synchronism with the camera scanning, and synchronizing signals are transmitted for that purpose.

Television Transmitter (A/V)
Electronic device that converts audio and video signals into modulated radio-frequency (rf) energy which can be radiated from an antenna and received on a television receiver. A television transmitter is really two separate transmitters integrated into a common cabinet. Video information is transmitted via a visual transmitter, while audio information is transmitted via an aural transmitter. Because video and audio have different characteristics, the two differ in terms of bandwidth, modulation technique, and output power level. Common transmitting antennas are generally used, and 2 transmitters feed this antenna via an rf diplexer or combiner.

Temperature Coefficient of Resistance (computer/microelectronics)
In microelectronic fabrication, term used to describe the amount of change in the resistance of material per degree of temperature rise.

Tempo (A/V, music, M/M)
Speed that musical compositions and MIDI files are played. Tempo is expressed as the number of beats per minute. Default value is 120 (moderato). Tempo also indicates the time interval of the appearance of a single Multimedia Move Player frame on a display.

Terminal (computer)
Traditional, older term for devices that allow users of a computer system to gain access to the system including: (1) batch terminals; (2) interactive terminals; (3) real-time terminals; (4) special purpose terminals.

Terminal Emulation (communications, computer)
Software that offers a workstation, personal computer, the appearance of responding to a mainframe or minicomputer as if it were a locally connected terminal.

Terminal Emulation (computer/Windows)
In Windows, a setting specified with Terminal that causes the computer to emulate a remote computer. Terminal emulation in Windows allow the computer to display data it receives and to use features available from the remote computer.

Terrestrial Link (communications)
Communications line that travels on or near or below ground (contrast with satellite link).

Test Tone (A/V)
In audio/visual production, a tone generated by the audio console to indicate a zero VU meter volume level. The zero VU meter test tone is recorded along with the color bars to provide a standard for the recording level.

Text Box (computer/Windows)
Windows object designed to receive printable characters typed from the keyboard. Visual Basic provides two basic types: single and multi-line. Entries in single line text boxes are terminated with an Enter keystroke. Multi-line boxes will accept more than one line of text either by a self-contained word-wrap feature or by a Ctrl-Enter key combination.

Text Editor (computer)
Traditional term to describe a computer program that allows a user to enter, alter, format, and store program and text-based information.

Text File (computer)
Disk file containing characters with values ordinarily ranging from ASCII character numbers 32 through 127. In a text file, lines of text are separated from one another with new line pairs, a combination of a carriage return (ASCII 13), and line feed (ASCII 10).

TFTP (communications, computer)
Trivial File Transfer Protocol. TFTP is an Internet communication protocol for transferring files to and from a UNIX host (may not have directory or passwords).

Theme (A/V)
Term used in audio/visual production to describe what the story is about; its essentials.

Theorem Proving (computer)
Term sometimes used to describe automated theorem proving, or proof finding and consequence fining. A proof-finding program attempts to find a proof for a certain given theorem. A consequence-finding program is given axioms, and then tries to deduce consequences from the axioms and to select potential consequences.

Thermal Compression Bonding (computer/microelectronics)
Process of diffusion bonding in which two prepared surfaces are brought into intimate contact, and plastic deformation is induced by the combined effects of pressure and temperature, which in turn, results in atom movement causing the development of a crystal lattice bridging the gap between facing surfaces and resulting in bonding.

Thermal Noise (communications)
Statistically uniform noise due to temperature (heat) of the transmission medium.

Thermionic Tube (A/V, communications)
An electron tube that relies upon thermally emitted electrons from a heated cathode for tube current. Thermionic emission of electrons means emission by heat. Oxide-coated equipotential cathodes are used in almost all receiving and medium-power transmitting tubes. They are also used in some high-power pulsed transmitting tubes, where the remarkable ability of the oxide cathode to emit very high current densities (10's of amp per square centimeter, for microsecond periods at low repetition rates) is exploited: majority of vacuum tubes are thermionic tubes.

Thermistor (computer/microelectronics)
Semiconductor device, the electrical resistance of which varies with the temperature. Its temperature coefficient of resistance is high, nonlinear, and usually of negative charge.

Thermoplastic (communications/photonics)
Material that can be deformed by applying a force when it is heated: it is used to record holograms in real time.

Thesaurus Application Feature (computer)
Application feature, within a word processing program that provides a look-up and comparison list of antonyms and synonyms for words within a document.

Thick Film (computer/microelectronics)
Conductive, resistive, and/or capacitive passive network deposited on a substrate using a metallic or resistive film which is more than five microns in thickness.

Thick Film Hybrid Integrated Circuits (computer/microelectronics)
Physical realization of a hybrid integrated circuit fabrication on a thick film network.

Thick Film Composites (computer/microelectronics)
Resistor, conductor, and dielectric compositions, the principle materials for making thick film circuits, available in paste form and consisting of metal, oxide, and glass powders.

Thin Ethernet (communications, computer)
More traditional Ethernet technology using a smaller diameter, more economical coaxial cable than the first Fat Cable Ethernet implementations. It was implemented by placing the cabling around the perimeter of the LAN workstations (long "bus" or long "ring").

Thin Film (computer, microelectronics)
Microscopically thin layer of semiconductor or magnetic material that is deposited onto a metal, ceramic, or semiconductor base. For example, the layers that make up a chip and the surface coating on high-density magnetic disks are called thin films. It is made up of a conductive, resistive, and/or capacitive passive network deposited on a substrate using a metallic or resistive film, which is less than five microns in thickness.

Thin Film Deposition (computer/microelectronics)
In microelectronics fabrication, there are three major thin film deposition types:

Chemical Vapor Type (CVD) involving a decomposition and reaction between gases on the surface of a heated substrate such that a solid layer is nucleated and grown. Metals are derived from the decomposition of metal halide; insulators may be formed by reacting halide with oxygen (oxides), ammonia (nitride), diborane (boride);

Evaporation Type involving the deposition of thin film in a vacuum, accomplished by heating the source material in a low pressure chamber so that it vaporizes and then condenses onto a cooler surface in a line-of-sight from the source;

Sputtering Type involving evaporation produced by ion bombardment of the source material, also known as cathode-sputtering.

Thin Film Deposition Materials (computer/microelectronics)
In microelectronics fabrication, there are four types of deposition materials used:

Conductors and Resistors, metals such as aluminum, gold, chromium, nickel, platinum, tungsten, alloys, and cermets deposited on silicon or other substrate;

Inorganic Dielectrics, film compounds produced by various vacuum evaporation processes and deposited on substrate to perform electrical functions (i.e. silicon monoxide);

Organic Dielectrics, insulating film compounds produced when organic vapors are heated under conditions in which polymerization and deposition occur (parylene, butadene, acrolein, divinyl benzene, are some examples of the organic compounds used).

Semiconductors, polycrystalline films deposited by vacuum or flash evaporation to produce high purity, single crystal silicon, or other silicon substrate.

Thin Film Hybrid ICs (computer/microelectronics)
In microelectronics fabrication, the physical realization of a hybrid integrated circuit (IC) fabricated on a thin film network.

Thin Film ICs (computer/microelectronics)
Physical realization of a number of electric elements entirely in the form of thin films deposited in a patterned relationship on a structural supporting material.

Thrashing (computer)
Term used in software engineering and analysis to describe a collapse of processing efficiency caused by attempted over-commitment of multiprogrammed main memory. If memory is overcommitted, at least one process will not have its working set fully present, and so will operate inefficiently (a working set can be the smallest set of instruction and data needed in main memory for efficient processing of a program). Thrashing has also been used to describe continuous and unnecessary disk access (DASD thrashing) caused by poorly planned program application or poorly programmed data manipulation.

Threefold (A/V)
Term used in audio/visual production to describe a property; three flats hinged together.

Throughput (computer)
Speed with which a computer can process data. A computer's throughput is a combination of its peripheral input and output speeds, its internal processing speed, and the efficiency of its operating system, and other system software, all working together.

Thyratron (communications)
Hot-cathode, gas-filled tube with one or more grids placed between the cathode and anode to provide control. Thyratrons operate in the gas arc region using mercury vapor where temperature control is possible, or an inert gas such as argon or xenon. In some tubes, both mercury and an inert gas are used to take advantage of the desirable features of each. For applications requiring great accuracy in control, fast de-ionization, and very high peak current of short duration (as in radar pulse-modulators) hydrogen gas is used.

THz (communications)
TeraHertz - One Trillion Cycles Per Second (1,000 x 1 billion, i.e. picosecond).

TIFF (computer)
Tagged Image File Format - a popular file format used to capture graphic images. TIFF stores images in a bit-mapped (raster graphics) format, developed by Aldus Corporation. It carries the extension TIF. TIFF files are used by most scanners to store images.

Tile (computer/Windows)
In Windows, a way of arranging open windows on the desktop so that no windows overlap but all windows are visible (each window takes up a portion of the screen).

Tilt (A/V)
Term used in audio/visual production to point the camera up and down.

TIME (computer/DOS)
DOS Command that displays or sets the current time in a personal computer. The user can accept the displayed time by pressing ENTER, or can type in a new time, first, to change the setting in the computer. DOS will maintain this new setting during the current session. In some newer model computers, this change will remain, as changed.

Time Base Corrector (A/V)
Term used in audio/visual production to describe an electronic accessory to a videotape/recorder that facilitates playback tapes or transfers electronically stable playbacks: the TBC corrects for slightly differing scanning cycles in the tapes.

Time Code (A/V, computer, M/M)
Method of identifying the time an event (such as a single motion picture or video frame) occurs in a format that can be understood by a computer (MIDI, SMPTE, etc.).

Time Compressor (A/V)
In audio/visual production, an instrument used to allow a recorded videotape to be replayed faster or slower without altering the original pitch of the audio.

Time Cues (A/V)
In audio/visual production, a cue to the talent about the time remaining in the show.

Time Delay (communications)
Modem communications feature that allows a computer to call another computer and transfer a file at some time in the future (clock time is programmed-in).

Time Division Multiple Access: TDMA (communications)
Synchronous TDM scheme for satellite capacity allocation.

Time Division Multiplexing: TDM (communications)
Division of a transmission facility into two or more channels by allotting the facility to several different information channels, one at a time (see TDM).

Time Integrating Element (communications/photonics)
Element that adds up its inputs over time (photo-detectors can have this characteristic).

Time Multiplexed Switching: TMS (communications)
Form of space-division switching in which each input line is a TDM stream: the switching configuration may change for each time slot (see TDM).

Time Out (computer)
If a device is not performing a task, the amount of time the computer should wait before detecting it as an error.

Time Sharing (computer)
Term used to describe a technique of organizing a computer so that many users can perceive the interaction with it as being simultaneous (or even instantaneous). Time sharing also refers to those multi-user systems in which arbitrary general purpose computing is performed and users operate independently from one another, often at locations that are remote from the computer, itself. Although time sharing was initially perceived as a programming convenience for debugging programs, the perception was extended to include the provision of a wide variety of on-line services and available large central memory resources, shared by a large user community.

Time Shifting (A/V)
In audio/visual production, a feature on some videocassette recorders that allows for the recording of a television program for later viewing on the VCR.

Time Signature (A/V, music, M/M)
Musical fraction where numerator indicates number of beats per measure and denominator indicates length of note representing one beat. A time signature of 3/4 (waltz time) has three beats per measure with a quarter note for one beat, and 12/8 (often used in transcribing Blues tunes) has 12 beats per measure with an eighth note for the beat.

Time Slice (computer)
Amount of processor time allocated to an application, usually measured in milliseconds.

Time Slot Interchange: TSI (communications)
Interchange of time slots within a time-division multiplexed frame (can be interleaved).

Time Stamp (A/V, computer)
Date and time data attributes applied to a disk file when created or edited. In MIDI files, a time stamp identifies the time MIDI events (such as Note On or Note Off) should occur, so that the correct tempo is maintained.

Title (A/V, computer, M/M)
In multimedia language, a commercial multimedia production designed for distribution on CD-ROMs or CD-I discs. Titles are usually created by multimedia authoring applications such as Authorware Professional for Windows from Authorware, Inc. In audio/visual terms, the studio title card or slide, or an electronically generated title.

Title Bar (computer/Windows)
Heading area (blue) of a window where the title (bright white) of the window appears. In Windows, the horizontal bar located at the top of a window and containing the title of the window. On many windows, title bar contains the Control-menu box, and Maximize and Minimize buttons.

TMSF Format (A/V, computer, M/M)
MCI time indicating: Tracks, Minutes, Seconds, Frames (used by CDAudio devices).

Toggle (computer/Windows)
Property of an object, such as a check box, that alternates its state when repeatedly clicked with the mouse or activated by a shortcut key combination. In microelectronic terms, to switch between two states ( "0" or "1") as in a flip-flop.

Toggle Switch (computer)
Hardware or software switch (can be a keystroke) that runs a function (on or off).

Token (communications, computer)
Data packet used to transmit header, address and information packets on a token bus or token ring local area network.

Token Bus (communications, LAN)
Medium access control technique for bus/tree Local Area Networks: stations form a logical ring, around which a token is passed. A station receiving the token may transmit information, and then must pass the token to the next station in the sequential ring (not the same as a token ring - physical ring). The traditional implementation used a "long bus", having the cabling (coaxial cable) installed around the perimeter or "up the center" of the LAN workstations. Newer technology, using Twisted Pair Cabling, can have "long leads" or "long drop cables" coming from workstations to a centralized hub (tiny bus implemented on the LAN hub).

Token Passing (communications, LAN)
Network access method using a continuously repeating frame (token) that is transmitted onto the network by the controlling computer. When a terminal or computer wants to send a message, it waits for an empty token. When it finds one, it fills it with the address of the destination station and some or all of its message. Every computer and terminal on the network constantly monitors the passing tokens to determine if it is a recipient of a message, in which case it "grabs" the message and resets the token status to empty.

Token Ring (communications, LAN)
Medium access control technique for rings. A token circulates around the ring, all of the time. A station may transmit information by seizing control of the token, insert a packet onto the ring, then release and retransmit the token (different than token bus). The traditional implementation used a "long ring", having the cabling (thick or thin coaxial cable) installed around the perimeter of the LAN workstations. Newer technology, using Twisted Pair Cabling, can have "long leads" or "long drop cables" coming from the LAN workstations to a centralized hub (tiny ring implemented on the LAN hub circuitry).

Tomography (computer)
Term used to describe a computer-assisted application for medical diagnosis using photographs in which the shadows of structures before and behind the section under scrutiny do not show. Computed Tomography (CT) through the use of a CT scanner and a computer system provides a method of scrutinizing only the section required: only that section is irradiated, and a computerized picture (rather than and x-ray) is produced of that section. CT produces images of cross-sections of the human body from measured attenuation of X-rays through the cross section. The capture mechanism, on a rotating gantry-type mechanism, moves around the patient, rather than having the patient move.

Tone Generator (A/V, music, M/M)
Synonym for a synthesizer.

Tongue (A/V)
In audio/visual production a term sometimes used to describe moving the camera boom from left to right or from right to left.

Toolbar (computer/Windows)
Series of shortcut buttons providing quick access to commands: usually located directly below the menu bar. Not all windows have a tool bar.

Toolbox (computer/Windows)
Collection of command buttons designated as tools, usually with icons substituted for the default appearance of a command button, that choose a method applicable to an object (usually graphic) until another tool is selected.

Tooling (computer/microelectronics)
In microelectronic fabrication, vacuum holes, grooves, and locating pins on the tool plate surface dedicated to a certain size substrate in order to position and hold the substrate during the print cycle of screen printing.

TO Package (computer/microelectronics)
Can-type integrated circuit chip configuration, an outgrowth of the original Transistor Outline package. Most common are the TO-5, TO-18, TO-47. The IC chip is mounted within the package, interconnected to terminals on the can, and then hermetically sealed.

Top-Down Design (computer)
Term used to describe a design technique that identifies basic program functions before dividing them into subfunctions called modules.

Topic (computer)
In DDE conversations, the file name or identifying title of a collection of data. When used with help rules, topic is the name of the subject matter of a single help screen display.

Topology (communications)
In a network, the pattern of interconnection between nodes, (bus, ring, star configuration): the physical layout of a network including cabling, routing, outlets, connections, nodes.

Touch Screen (computer)
Video display that has a screen with an imbedded membrane, or a physical contact break, that provides the user with a facility to point and touch an area of the screen to interact with the computer program much the same way as using a mouse or other graphic user interface device. Touch screen capability can be ordered as an optional screen, or can be added on at a later date with a peripheral attachment to an existing screen.

Tower Configuration (computer)
Floor standing or Desktop cabinet that is taller than it is wide that houses the PC's CPU.

Trace (computer/microelectronics)
Execution of program instructions one at a time to check or report the contents of registers, accumulators, and specified memory locations at each stage. It is also used as a debugging aid with a display that chronicles the actions and results of the individual steps in a program.

Track (A/V, computer, M/M)
Storage channel on disk or tape. On disks, tracks are concentric circles or spirals (CD, videodiscs). On tapes, they are parallel lines. Their format is determined by the specific drive they are used in. On magnetic devices, data bits are recorded as reversals of polarity on a magnetic surface. On CDs, data bits are recorded as physical pits under a clear, protective layer. In MIDI terminology, the notes appearing on a single musical staff. When scoring an arrangement for multiple instruments, each instrument is ordinarily assigned to an individual track. A MIDI track is similar to an audio track of a multitrack tape recorder. MIDI sequencer applications are often priced by the maximum number of tracks they offer. Sixteen tracks is the minimum number possible for an application to be usable. Most sequencer applications provide at least 64 tracks. With CD-Audio drives, track refers to a specific selection on the compact audio disk.

Trackball (computer)
Input device that is used as a mouse alternative. It is a stationary unit that contains a movable ball that is rotated with the fingers, that then moves the cursor on the screen. Trackballs are useful when there is a minimum amount of desk top space available or for notebooks and other portable computers where a desktop surface area is not available.

Tracking (A/V)
In audio/visual terms, an electronic adjustment of the video heads on a video recorder, so that, in the playback phase, they match the recording phase of the tape. It prevents picture breakup and misalignment especially in tapes that have been recorded on a machine other than the one used for playback. With videocassette recorders, this feature provides for tracking adjustments in prerecorded tapes. Even though the tape speed of VCRs is set at the factory, there may be a slight difference from one VCR to another. Tracking control adjusts to compensate for any difference in speed and to match that of a previously recorded tape from another VCR.

Tracking Speed (computer/Windows)
In Windows, a measurement of the responsiveness of the mouse interface. The higher the tracking speed, the farther Windows moves the mouse pointer in response to a given mouse movement. Control Panel can be used to adjust the mouse tracking speed.

Transaction-Based Applications (computer)
Application system that provides a specialized type of on-line system where on-line implies that the user of the system is able to interact directly with a computer. The term transaction-based means that the user requests and receives application system functions to process a series of individually distinct inputs called transactions. Successful transaction-based system for airline reservations, order processing and inventory control, credit approval, and management information, have been in use for over 30 years. In each case, on-line transaction processing, with its delivery of timely information directly to the user, offers accurate data, and improves control of the total system resources.

Transducer (A/V, communications)
Device or element which converts an input signal into an output signal of a different form. An example is the microphone, which converts vibrations caused by an impinging sound wave into an electrical signal. This electrical signal can be measured to determine the magnitude of the sound wave; it can be recorded (through the use of another transducer); or it can be used to control some instrument. A different type of transducer is the photoelectric cell, which produces and electrical signal in response to incident light. The most widely used transducer converts an electrical signal into a mechanical signal (a vibration or a displacement) or vice versa. This class of transducer includes phonograph pickups, loudspeakers, car horns, doorbells, and underwater transducers.

Transformer (A/V, communications, microelectronics)
Electrical component used to transfer electric energy from one alternating-current (ac) circuit to another circuit by magnetic coupling. Essentially, it consists of two or more multiturn coils of wire placed in close proximity to cause the magnetic field of one to link to the other. In general, the transformer accomplishes one or more of the following between two circuits: (1) a difference in voltage magnitude; (2) a difference in current magnitude; (3) a difference in phase angle; (4) a difference in impedance level; (5) a difference in voltage insulation level, either between the two circuits or to ground. Transformers are used to meet a wide range of requirements. They are often classified according to the frequency they are assigned to: power transformers are for power-frequency circuits; audio transformers are for audio-frequency circuits, etc. Other common types are: Power transformers (taps, parallel operation, phase transformation, overload transformation); Audio, Video & Radio Frequency transformers.

Transient Error (communications)
Term used to describe a "soft" network transmission error that is often intermittent and easily corrected by re-transmission at the point (or several packets previous) of error.

Transistance (computer/microelectronics)
Characteristic of an electric element which control voltages or current so as to accomplish gain or switching action in a circuit. Examples of the physical realization of transistance occur in transistors, diodes, saturable reactors, limiters, and relays.

Transistor (communications, computer)
Semiconductor device that is used to amplify a signal or open a closed gate in a circuit. In digital computers, it functions as an electronic switch. When activated, it bridges the gap between two wires and allows current to flow. The gap is a material that normally resists electricity, but can change its state. When activated (a voltage on the gate), it becomes conductive and allows current to flow (from source to drain). Transistors, resistors, capacitors and diodes, make up logic gates. Logic gates make up circuits, and circuits make up electronic systems. It is an active semiconductor, having three or more electrodes, and capable of performing the functions of tubes, including rectification and amplification. Germanium and silicon are the main materials, with impurities introduced to determine the conductivity type (n-type have an excess of free electrons, p-type have a deficiency of electrons).

Transistor Testers (computer/microelectronics)
Equipment and instruments which detect or measure leakage current, breakdown voltage, gain, or saturation voltage. Some testers are computer operated.

Transistor-Transistor-Logic (computer/microelectronics)
Logic system which evolved from Diode Transistor Logic (DTL) wherein the multiple diode cluster is replaced by a multiple-emitter transistor. A circuit which has a multiple emitter input and an active pullup network.

Transmission Channel (communications)
Path between two nodes in a network. It may refer to the physical cable, the signal transmitted within the cable or to a subchannel within a carrier frequency. In radio and TV, it refers to the assigned carrier frequency.

Transmission Lines (communications, electrical)
System of conductors suitable for conducting electric power or signals between two or more termination points. Commercial-frequency electric power transmission lines connect electric generating plants, substations, and their loads. Telephone transmission lines interconnect telephone subscribers and telephone exchanges. Radio-frequency transmission lines transmit high-frequency signals between antennas and transmitters or receivers. Different types of transmission lines include: open-wire, coaxial, travelling waves; pulse transients; standing waves; tapered transmission lines.

Transmission Medium (communications)
Physical path between transmitters and receivers in a communications system.

Transparency (communications/photonics)
Thin optical element that modulates light that passes through it (crystal, overhead transparency acetate, fiber optic cable, or a slide in a slide projector can be examples).

Transparency (A/V, computer/printing)
Any artwork viewed by having light pass through it, rather than reflecting off of it.

Transponder (communications)
Receiver and transmitter in a communications satellite. The transponder receives a microwave signal from earth (up link), amplifies it and retransmits it back to earth at a different frequency (down link). There are several transponders on a satellite.

Transport Layer (communications)
Fourth Layer of the ISO/OSI Model concerned with protocols for error recognition and recovery, as well as regulation of information flow.

Transport Mechanism (A/V)
In audio/visual production, this term is sometimes used to describe the videocassette recorder mechanism responsible for the physical manipulation of the video tape.

Transport Protocol (communications, computer)
Communications protocol that is responsible for establishing a connection and ensuring that all data has arrived safely. It is defined in Layer 4 of the ISO/OSI model.

Transpose (A/V, music)
In music, adjusting all notes of a composition or portion of it, by a specified pitch interval (number of halftones). Transposing changes the key in which the music is played.

Transverse Scanning (A/V)
In audio/visual terms, the direction of the video signal scanning in quadruplex recorders. Transverse scanning puts the signal across (transverse) the videotape rather than in a helical (diagonal) or lengthwise pattern.

Trap (computer)
Term used to describe an automatic transfer to a special routine, at the occurrence of an exceptional event in a processor, that will handle this transfer. The term trap and interrupt are sometimes thought to be synonymous, but the term is used singularly to describe the range of exceptional events that occur within the central processing unit.

Trapping (computer/printing)
Creating small overlapping areas, in printing processes, wherever two colors meet, to ensure that slight mis-registrations on presses do not show up as white gaps.

Travelling-Wave Tube (communications)
Microwave electronic tube in which a beam of electrons interacts continuously with a wave that travels along a circuit, the interaction extending over an appreciable distance measured in wave-lengths. Travelling-wave tubes are normally used in amplifiers with exceedingly wide bandwidths. Travelling-wave amplifiers serve at the inputs to sensitive radars or communication receivers. High-power travelling-wave amplifiers, operated as the final stages of radars or scatter communication transmitters, deliver pulsed powers exceeding one megawatt (million watts). In satellite usage, lightweight travelling-wave amplifiers develop 35 watts continuously at 45% to 60% overall efficiency.

Treatment (A/V)
In audio/visual terms, the brief description of a prospective television program.

Tree (communications)
Network topology in which stations are attached to a shared transmission medium: the medium is a branching cable emanating from a head-end, with no closed circuits. Transmissions propagate throughout all branches of the tree, but must use the hierarchical path of the branches, interconnected to the tree, up to the head-end, and then back down the tree, back through the branches, to the intended receiver/node. Direct connection and transmission/reception between two nodes on the tree (branches) is prevented.

TREE (computer/DOS)
DOS Command that displays the disk directory structure.

Tree Pane (computer/Windows)
In Windows, one of the two directory views used by File Manager (the other is the directory pane). The tree pane shows the subdirectory structure of the current disk.

Tree Structure (communications, computer)
Hierarchical structure with many branches. Directories within DOS are arranged in a tree-like structure, with subdirectories as branches off the main directory tree.

Tremolo (A/V, music)
Musical term often used to indicate a rapid but small change in a note's pitch (frequency modulation). When applied to synthesizers, tremolo often refers to small changes in the sound's amplitude (amplitude modulation).

Trichromatic (computer, M/M)
In computer graphics, the use of red, green, and blue to create all colors in the spectrum.

Trigger (communications, computer, microelectronics)
Timing pulse used to initiate the transmission of logic signals through the appropriate circuit signal paths.

Trigger Circuit (communications, computer, microelectronics)
Electronic circuit that generates or modifies an existing waveform to produce a pulse of short time duration with a fast-rising leading edge. this waveform, or trigger, is normally used to initiate a change of state of some relaxation device, such as a multivibrator. the most important characteristic of the waveform generated by a trigger circuit is usually the fast leading edge. The exact shape of the falling portion of the waveform is of secondary importance, although it is important that the total duration time is not too great. A pulse generator such as a blocking oscillator may also be identified as a trigger circuit if it generates sufficiently short pulses.

Trimming (computer/microelectronics)
Removal of film resistor material in order to increase the resistance to a certain value. Two types of equipment are used for this purpose. The air abrasive jet trimming system (AJT) depends on a precisely controlled stream of abrasive particles to carve away small portions of a thick film resistor. Laser systems are used for thick and thin films. With lasers, the material is burned away.

Tripod (A/V)
Three-legged, camera mount, usually connected with a dolly for easy mobility.

Trivial File Transfer Protocol: TFTP (communications, computer)
Popular File Transfer Protocol, as part of TCP/IP (see File Transfer Protocol)

Trojan Horse (computer)
Program routine that invades a computer system by being secretly attached to a valid program that will be downloaded into the computer. It may be used to locate password information, or it may alter an existing program to allow easier access to it. A virus is a Trojan horse that continues to infect programs over and over.

TrueType (computer/printer/Windows)
Scalable font technology from Apple that is licensed by Microsoft. Each font contains its own algorithm for generating the final bit maps.

Trunk Cable (A/V, communications)
Section of cable television distribution system through which signals are sent and to which distribution cables are connected. Trunk cables begin at the originating source of the signal reception (head end) and they are normally not tapped into for any subscriber drop cables. Once populated areas are reached, distribution cables are used for front and back lot distribution, off of which the household drops are run (from multitap devices).

Truth Table (computer)
Chart which tabulates all the combinations of possible states of the inputs and outputs of a circuit. It tabulates what will happen at the output for a given input combination.

TSI (communications, computer)
Time Slice Intervals: term for how a file server divides time on a Local Area Network.

TSR (computer)
Terminate and Stay Resident - programs that remain in memory so that they can be instantly activated. TSR programs have become popular in order to have instant access to calculator, calendar or dictionary, while word processing or doing other applications.

TTL (computer)
Transistor-Transistor Logic - a digital circuit where the output is derived from two transistors. It is a logic system which evolved from Diode Transistor Logic (DTL) wherein the multiple diode cluster is replaced by a multiple-emitter transistor. A circuit which has multiple emitter input and an active pullup network.

TTS (communications, computer)
Transaction Tracking System: method to ensure data integrity on multi-user databases.

Tuner (A/V, communications)
Device containing circuits that can be tuned to the carrier frequency of a desired transmitter in the frequency range for which that tuner is designed. The tuner serves to select the desired carrier frequency while rejecting the carrier frequencies of all other stations that may be on the air at that time. A tuner for a television receiver ordinarily contains only the radio-frequency amplifier, local oscillator, and mixer stages. A radio tuner usually contains, in addition, the i-f amplifier and second-detector states so that it can feed an audio signal directly into a separate audio amplifier and loudspeaker system.

Tungsten-Halogen (A/V)
Type of lamp filament used in quartz lights. The tungsten is the filament itself; the halogen is the gaseous atmosphere contained within the bulb surrounding the filament.

Tuning (A/V, communications)
Process of adjusting the inductance or capacitance, or both, in a tuned circuit, for example, in a radio, television, or radar receiver or transmitter, so as to obtain optimum performance at a selected frequency. The tuning procedure that is carried out during manufacturing or servicing of equipment involves the adjustment of controls located inside or at the rear of the equipment. These are adjusted so that the main tuning control on the front of the panel will serve to adjust all tuning circuits in the equipment simultaneously when a change of frequency is desired.

Tunnel Diode (communications, microelectronics)
Two-terminal semiconductor junction device which does not show rectification in the usual sense, but exhibits a negative resistance region at very low voltage in the forward-bias characteristic, and a short circuit in the negative-bias direction.

Tunnelling In Solids (microelectronics)
Quantum-mechanical process which permits electrons to penetrate from one side to the other through an extremely thin potential barrier to electron flow. The barrier would be a forbidden region, if the electron were treated as a classical particle. A two-terminal electronic device in which such a barrier exists and primarily governs the transport characteristic (current-voltage curve) is called a tunnel junction. The tunnel diode demonstrated (1960) the first convincing evidence of electron tunnelling in solids, a phenomenon which had been clouded by questions for decades. The tunnelling phenomenon is used in many fields. Small-area tunnel junctions are used for mixing and synthesis of frequencies ranging from direct current (dc) to the infrared region of the spectrum. This leads to absolute frequency measurement in the infrared and subsequently provides the most accurate determination of the speed of light.

Turnaround Time (computer)
Elapsed time from the time a batch job is submitted to be run on a computer until the results are available. In an MIS (management information systems) group, the turnaround time could also extend from the time when a processing job requirement arrives to be processed, to the time when the completed job is returned to the end-user.

Turnkey (computer)
Term used to describe a complete systems implementation where a single person, or group of specialists prepare a facility. set up all necessary premises, equipment, supplies, and operating personnel to bring a project to a state of operational readiness: all the client must do is "turn the key" to begin full and effective usage of the new facility. Sometimes the individual or contracted group will continue to operate the facility (can be called facilities management), while in other cases, the client assumes operational control.

Turn-On Time (computer/microelectronics)
Time required for an output to turn on (sink current, to ground output, to go to O-V). It is the propagation time of an appropriate input signal to cause the output to go to O-V.

Turret Lens (A/V)
Lens mounted on the turret of a monochrome camera: usually in contrast to a zoom lens.

TV Lines (A/V)
In audio/visual production, a term sometimes used to describe the means of specifying horizontal resolution in a video image. Each TV line is the vertical equivalent of a horizontal scanning line. AN NTSC video image with a horizontal resolution of 340 TV lines has a horizontal resolution which is equal to its vertical resolution. In the NTSC system a Megahertz (1,000 Hz) is required for every 80 TV lines of horizontal resolution.

TV Tuner (A/V)
In consumer television sets, the electronic component that contains circuitry needed to tune television or cable channels.

Twinaxial (communications)
A cable that is similar to coaxial cable, but with two inner conductors instead of one.

Twip (computer/Windows)
Windows's smallest unit of graphic measurement. A twip is a twentieth of a point or 1/1,440th of an inch.

Twisted Pair (communications)
A pair of small insulated wires that are commonly used in telephone cables. The wires are twisted around each other to minimize interference from other wires in the cable. Cables containing from one to several hundred twisted pairs are used in myriads of electronic and telephone connections. Twisted pair wires have limited bandwidths compared to coaxial cable or optical fiber cable.

Type (computer/printing)
In computer terms, generally referred to as Data Type, however the term is also used to describe the style of displayed or printed characters, as in a typeface.

TYPE (computer/DOS)
DOS Command that displays the contents of a file. This command can also be used with redirection characters to use the file as input to another command, such as MORE. The command only displays the file until it reaches and end-of-file marker. If the user wants to see the contents of the file beyond the end-of-file marker, they use the COPY command with CON as the destination. When a binary file is displayed on the screen, such as graphics and program files, the display will be unintelligible. Some text files, such as word processing files, contain unusual characters which the word processor application uses to record how the text is formatted. These characters may not appear when using the word processor, but may appear when the TYPE command is used.

Typeface (computer/printing)
Print or display type of single design. Typeface is confused with Font which means a particular size of typeface. A typeface may be a member of a type family including related designs with attributes such as bold, Roman, Italic, compressed, or extended.

Typeover Mode (computer)
Wordprocessing mode whereby each character typed overwrites previous characters.

Typeset Quality (computer/printer)
Printer resolution that approaches typesetting quality, usually 1,200 to 2,540 dots per inch.

Type Size (computer/printer)
Size, in points, of a particular font or typeface.