P

P.A. (A/V)
Term used to describe a public address loudspeaker system (same as studio talkback).

PABX (PBX - EPABX) (communications)
Private Automatic Branch Exchange (PBX, PABX, EPABX): owner/operated switching system that electronically interconnects telephone extensions with one another, as well as to the outside telephone network; it can perform telephone management functions such as least cost/best way routing for calls, call forwarding, conference calling, and call accounting. Modern PABXs use all-digital switching and can often handle digital terminals and phones as well as the common analog telephone (EPABX, PABX, PBX).

Pace (A/V)
In Audio/Visual, perceived duration of a show or show segment (part of subjective time).

Pack (computer)
Term used for popular data compression and de-compression application programs.

Package (A/V, computer/Windows)
Icon for embedded or linked objects. When a package is chosen, the application used to create it either plays the object (sound, video), or displays the object. In Audio/Visual production, a self-contained field report of a news event, complete with introduction and conclusion. All the studio anchor person has to do is introduce the recorded event.

Packaging (computer/microelectronics)
Process of physically locating, connecting, and protecting devices or components.

Packaging Density (computer/microelectronics)
Number of devices per unit volume in a working system or subsystem.

Packet (computer,communications)
Group of bits/bytes that can be sent/retrieved as a unit: with header & address route.

Packet Assembler/Disassembler: PAD (communications, computer)
Device used with an X.25 network to provide service to asynchronous terminals.

Packet Switching (communications)
Technique for handling high-volume traffic in a network by breaking apart messages into fixed length packets that are transmitted to their destination through the most expedient route. All packets in a single message may not travel the same route (dynamic routing). The destination computer reassembles the packets into their proper sequence. This method is used to efficiently handle messages of different lengths and priorities in large networks, such as Telenet, Tymnet, AT&T's Accunet, Sprint/MCINet. X.25 is the international standard for such a network. Packet switching networks also provide value added services.

Packetized Voice (communications)
Transmission of voice conversations in a packet switching network.

Pad (computer/microelectronics)
In microelectronic fabrication, the bonding area for integrated circuit creation. In communications, an abbreviation for Packet-Assembler-Disassembler.

Page (computer/Windows)
In ClipBook, one complete entry that has been pasted in. In memory, a fixed-size block.

In microelectronics, a natural grouping of memory locations by higher order address bits.

Page Composition Program (computer)
Software package for designing and producing professional looking documents that combine text and graphics. Also called a page makeup or desktop publishing program.

Page Description Language (computer)
Language built into printers used in desktop publishing: used by a desktop publishing program to control the way a printer prints a page.

Page Frame (computer)
Space in main memory in which to place a page.

Page Layout (computer/printer)
In publishing, the process of arranging text and graphics on a page.

Page Makeup Program (computer)
Software application program for designing and producing professional-looking documents that combine text and graphics. Also called a page composition program, or a desktop publishing application program.

Pages (computer)
Equal-size blocks into which a program is divided for storage.

Paging (computer)
Keeping program pages on disk and calling them into memory as needed.

Paging File (computer/Windows)
Special file on the hard disk. With virtual memory, some of the program code and other information is kept in RAM while other information is temporarily swapped to virtual memory. When that information is required again, Windows Networking pulls it back into RAM and, if necessary, swaps other information to virtual memory (same as swap file).

Paint (computer)
To "paint" the screen using a mouse to simulate a paintbrush. To transfer a dot matrix image as in the phrase "the laser printer paints the image onto a photosensitive drum".

Paint Program (computer)
Graphics program that allows the user to simulate painting on the screen with the use of a graphics tablet or mouse. Paint programs create raster graphics images.

PAL (A/V)
Phase Alternative Line system - the television transmission standard of Western Europe (except France - which uses the SECAM standard). PAL displays 625 lines per frame at a rate of 25 frames per second.

Palette (computer/Windows)
Windows data structure defining the colors of a bit-mapped image in RGB format.

Palmtop Computer
One of the smallest consumer computers available, weighing less than 1 pound.

Pan (A/V, M/M)
Capability of a synthesizer or sound board to alter the volume on the left and right stereo audio channels creating the illusion of movement of the sound's source. In video camera production, the movement of the camera from side to side (manually or remotely).

Pancake (A/V)
Makeup base, or foundation makeup, usually water-soluble: applied with a small sponge.

Pan Stick (A/V)
Foundation makeup with a grease base: used to cover beard shadow or skin blemishes.

Pantograph (A/V)
Expandable hanging device for lighting instruments.

PANTONE MATCHING SYSTEM (computer/printing)
PANTONE, Inc. check-standard trademark for color reproduction and color reproduction materials; a system of solid ink color mixing, matched to swatchbook samples. Now PANTONE standards are available for computerized color matching.

Paper and Pencil Editing (A/V)
Process of examining all various shots and then logging every editing decision in an editing log or editing shot sheet.

Paper Tape (history/communications/computers)
Punched paper tape was one of the first storage mediums used for the preparation, storage, and transmission of data in various applications. Slow-speed paper tape was used as a control device for numerically controlled machine tool operations. At higher speeds, paper tape was used for typesetting, telegraphic and data transmission, and automated typewriting, as well as for storing computer programs and data, and also for other data processing functions (carriage movement control in line printers).

Parallel (computer/microelectronics)
Refers to the technique for handling a binary data word which has more than one bit. All bits are acted upon simultaneously (see also Serial).

Parallel Adder (computer/microelectronics)
Conventional technique for adding where the two multibit numbers are presented and added simultaneously (parallel). A ripple adder is still a parallel adder: the carry is rippled from the least significant to the most significant bit. Another type of parallel adder is the "look ahead" or "anticipated carry" adder.

Parallel Algorithms (computer)
With the advent of multiprocessors, parallel algorithms and models for parallel computation have received a great deal of attention. In numerical analysis, several processes originally intended to be run on single processors, by design or by necessity, have been recast in parallel form. Often, in these new algorithms, all processors synchronously execute the same operations (SIMD architectures).

Parallel Circuit (computer/microelectronics)
Electric Circuit in which the elements, branches (elements in series), or components are connected between two points with one of the two ends of each component connected to each point. In parallel circuit, the potential difference (voltage) across each component is the same. The lights in a household electrical wiring scheme are connected in parallel so that each load will have the same voltage (120 volts), however, each load may draw a different current (0.50 amp in a 60-watt bulb - to, for example, 3 amps in a personal computer.

Parallel Conversion (computer)
Method of systems conversion in which the old and new systems are operated together until the users are satisfied that the new system performs to their standards.

Parallel Gap Welding (computer/microelectronics)
Type of resistance welding wherein electrodes contact the work from one side only. Mechanisms by which bonding occurs is virtually always fusion. The process is well suited to welding component leads to planar surfaces such as IC leads to PCB conductors.

Parallel Interface (computer)
A multi-line channel that transfers one or more bytes simultaneously. For example, personal computers often connect printers via a Centronics 36-wire parallel interface, which transfers one byte at a time over eight wires, the remaining wires are used for control signals. Large computer parallel interfaces transfer more than 1 byte at a time (contrast with serial interface).

Parallel Operation (computer/microelectronics)
Processing of all bits of a word (byte) simultaneously using a parallel bus or transmission.

Parallelity (computer/microelectronics)
In microelectronics fabrication, the relationship of screen to work-holder and print head in screen printing. Each should be parallel to one another in order to print accurately.

Parallel Port (computer)
External connector on a computer that is used to hook up a printer or other parallel device. On PCs, the parallel port uses a DB-25 connector at the computer side and a Centronics 36-pin connector at the printer side.

Parallel Processing (computer)
Processing of more than one task on a computer system may be truly simultaneous or apparently simultaneous. True simultaneity is defined by operating multiple functions in the same time. Apparent simultaneity may be achieved by various multiplexing algorithms applied to a single hardware unit. Both true and apparent simultaneity require degrees of logical disconnectivity which enable tasks to run independently of each other for periods of time.

Architecture within a single computer that performs more than one operation at the same time; or - a multiprocessing architecture made up of multiple processors or multiple computers. In a SIMD architecture, such as an array processor, one operation is performed on many sets of data. In a MISD architecture, multiple computers work on different parts, simultaneously.

Parameter (A/V, computer/microelectronics, DOS/Windows)
Equivalent of an argument but used with a procedure not a function. The terms parameter and argument are often used interchangeably, but a parameter is a variable required by a procedure to perform its function and is passed to the procedure by the call statement. Parameters may be passed by reference, in which case the procedure using it may change its value; or it may be passed by value, in which case its value as seen by the calling program is unchanged by any action by the procedure. Distinction is made between arguments of functions and parameters of procedures. In Windows, API functions change the value of arguments passed to them.

When applied to sound synthesizers, a parameter is an element that varies one of the properties of a sound. In microelectronic fabrication, any specific characteristic of a device. When considered together, all parameters of a device describe its operational, physical characteristics.

In DOS and Windows, information added to the command that starts an application. This information determines how the application will run. A parameter can be a filename.

Parametric Amplifier (communications)
Highly sensitive, low-noise amplifier for ultrahigh frequency, microwave radio signals, using, as active element, an inductor or capacitor whose reactance is varied periodically at another microwave or ultrahigh frequency. A varactor diode is commonly used as the variable reactor.

Parasitic Oscillation (A/V, communications, computer)
Undesired oscillation which may occur in any type of circuit such as an audio, video, or radio frequency amplifier, oscillator, modulator.

Parity (computer)
Synonym for equality. Parity checking is an extensively used error-checking facility provided to insure correct recording of data, its input into a computer system, and its transfer within the system, transmission included.

Parity Bit (communications, computer)
Bit added to each byte to alert the computer to an error in data transmission. Also called a check bit. Also, a check bit appended to an array of binary digits to make the sum of all the binary digits, including the check bit, always odd or always even.

Parity Checking (communications, computer)
Error detection technique that checks for the accurate transmission of digital data either within the computer system or over a network. Parity checking uses an extra bit (ninth bit) that holds a 0 or 1 depending on the data content of the byte. For even parity systems, the parity bit is made a 1 when there are an even number of bits in the byte. In odd parity, the parity bit is a 1 when the byte contains an odd number of bits. In order to detect a transmission error, the parity bit is tested each time a byte is transmitted.

Park (computer)
To safely disengage the read/write head of the hard disk drive, with a utility program, most often used during relocation of the personal computer (but can be used anytime).

Parotting (A/V)
In Audio/Visual production, scripting a lead-in to a sound bite in which the lead-in text uses the exact words of the opening of the sound bite: also called "echo effect".

Parsing (computer)
Process by which the phrases in a string of characters in a language are associated with the component names of the grammar that generated the string. The structural description of a string that results from parsing is called the parse. A parse is often shown as a tree. Parsing is the heart of the process of compilation of source programs in a high-level language into machine language. The compiler must take the string of characters written by the programmer and associate appropriate substrings of characters with the syntactic components of the high-level language in order to determine structure of the given program so that it can be translated into machine code.

Particle Impact Noise Detection: PIND (computer/microlectronics)
In microelectronic fabrication, testing equipment that detects loose, foreign particles that may be present in a hermetic package. The package is placed on a shaker table where it is in intimate contact with an acoustic transducer that drives an ultrasound amplifier.

Partition (computer)
Portion of a physical disk that functions as though it were a physically separate unit. Also, dividing a hard disk into several user volumes or areas.

Parts Handling (computer/microelectronics)
Devices used to load and unload substrates during screen printing and drying operations.

Passivation (computer/microelectronics)
Growth of an insulating layer on the surface of a semiconductor to provide electrical stability by isolating the transistor surface from electrical and chemical conditions in the region. It reduces reverse-current leakage, increases breakdown voltages, and improves the power-dissipation rating.

Passive Elements (computer/microelectronics)
Elements such as resistors, inductors, or capacitors: any element without gain.

Passive Radar (communications)
Technique for surveillance, mapping, navigation, and guidance that employs the reception of microwave-frequency energy radiated by warm bodies, or reflected from other sources. It is similar in principle to infrared systems used for the same purpose.

Passive Star (communications)
A network topology that joins cabling from several nodes without providing any additional processing (contrast with active star).

Passive Substrate (computer/microelectronics)
Substrate for an integrated component which may serve as physical support and thermal link to a thick or thin-film integrated circuit, but which exhibits no transistance. Examples of passive substrates include glass and ceramics.

Password (communications, computer/Windows)
Unique string of characters that must be provided before logging on or an access is authorized to a system. A password is a security measure used to restrict logging on to user accounts and access to computer systems and resources. For Windows Networking, a password for a user account can be up to 14 characters and is case-sensitive.

Password Uniqueness (communications, computer/Windows)
Number of new passwords that must be used by an account before an old password is re-used.

Paste (computer/microelectronics, DOS/Windows)
Synonymous with "composition" or "ink" in relating to screenable, thick film materials. In Windows, paste can refer to a command to transfer the contents of a Clipboard to an application. Many applications have a Paste command that performs this task.

Patch (A/V, communications, computer)
For A/V and communications panels, a patch can be a short cable with accompanying connectors on both ends for short connections between two receptacles. When used with MIDI terminology, a numerical value from 0 to 127. This value indicates to the receiving device that a specific voice is to be used to play notes transmitted by MIDI Note On messages on the device's MIDI channel. In other programming usage, patch means fixing an error in an executable file by modifying its code directly rather than be recompiling it from the original source code. Patch also describes correcting a bug in an executable file, again, without the necessity of recompiling the source code.

Patchboard (A/V)
Device that connects various inputs with specific outputs (also called a patch bay).

Path (communications, computer)
In communications, a route between any 2 nodes - same as line, channel link or circuit.

In database management, the route from one set of data to another.

In programming, a set route taken by the program to process a set of data.

PATH (computer/DOS)
DOS Command that selects directories that DOS will search for program and batch files when it does not find the files in the current directory. When a user wishes to start a program such as WordPerfect, Word, Excel, etc., from any directory on the disk and have DOS find the program files that the user needs, they will want to enter a PATH statement with references to the directories that are needed. This command sets the environment variable PATH to the value of the PATH command.

Path Control Network (communications, computer)
Responsible, under IBM's SNA (system network architecture) for identifying addresses of devices that wish to converse and then establishing a network path for them.

Pathname (computer/DOS)
Directions to a directory or file within the personal computer filing system.

Pattern (A/V, computer, M/M)
A MIDI-related term describing a sequence of percussion sounds, usually one or two measures in length. Different patterns are then combined into songs by percussion synthesizers called drum machines. Patterns are usually repeated for a number of bars, often interrupted with a break or drum solo, followed by another repetitive set of patterns creating a percussion track to back a tune.

Pattern/Image (computer/microelectronics)
Open area in the screen through which the ink penetrates to become the printed image on the substrate, in screen printing for microelectronic fabrication.

Pattern Projector (A/V)
Ellipsoidal spotlight with cookie (cokuloris) insert, projecting the cookie pattern as shadow.

Pattern Recognition (computer)
Area of computer science that is concerned with the classification or description by computer of objects, events, or other meaningful regularities in noisy or complex environments. It is the study of ideas and algorithms that provide computers with a perceptual capability to put abstract objects, or patterns, into categories in a simple, reliable way. The major applications of pattern recognition fall into three main categories: (1) patterns in images (spatial patterns); (2) patterns in time (temporal patterns); (3) patterns in more abstract data environments.

PAUSE (computer/DOS)
DOS Command that suspends execution of a batch file and displays a message instructing the user to press a key so the batch file will continue. This command is usually preceded by commands that display instructions to the user, such as turning the printer on or putting a disk in a drive. The batch file displays the message after the ECHO command, and then displays the message "Press any key to continue..."

PBX (communications)
Private Branch Exchange: switching system owned and operated by the customer, on the customer's premises, providing the same services as a central office telephone service.

PC (computer)
Any personal computer - or - all machines that conform to the IBM PC and PS/2 standards - or the original PC models (PC, XT, AT) in contrast with PS/2 models.

PCL (computer/printer)
Printer Control Language - the printer language from Hewlett-Packard that activates the LaserJet printers. PCL has become an industry standard that is used with many different brands of laser printers and typesetters. If a machine supports the PCL language, it accepts the same printer files that are sent to LaserJet printers.

PCM (communications, computer)
Pulse Code Modulation - a technique for digitizing speech by sampling the sound waves and converting each sample into a binary number. PCM uses waveform coding which samples a 4KHz bandwidth 8,000/sec. Each sample is an 8 bit number, resulting in 64K bits per second.

PCX (computer)
File extension created by ZSoft Corporation for storing images created by its PC Paintbrush application. PCS bit-map files can be monochrome or color and are used by many other bit-mapped image creation (paint) and display applications.

Peak Program Meter (A/V)
Meter in audio console to measure loudness: especially sensitive to volume peaks, it indicates when there is overmodulation (also called a PPM).

Pedestal (A/V)
Heavy camera dolly that permits a raising and lowering of the camera while on the air. Also, to move the camera up and down via the studio pedestal. Also an adjustment in the video black level reference measured against a standard on the oscilloscope.

Peek/Poke (computer)
To view and alter an element of memory be calling up a specific memory address location. Peek displays the information on the screen; Poke changes the information.

Peer-to-Peer Communications (communications)
Communications from one user to another user on a network; it implies the ability to initiate the session at the user's discretion.

Peer-to-Peer Network (communications)
Local area network that allows all users access to data on all workstations. A dedicated file server is not required, but may be used.

Pen-Based Computing (computer)
Computer whose primary input is handwriting, which is entered by means of a pen-like stylus. The computer has a flat screen (touch-sensitive screen).

Perambulator Boom (A/V)
Special mount for a studio microphone: an extension device, or boom, is mounted on a dolly, called a perambulator, that permits rapid relocation anywhere in the studio.

Percipient (A/V)
Television viewer in the act of perceiving television audio and video stimuli (a television program): implies a certain degree of involvement in watching a television program.

Performer (A/V)
Person who appears on camera in non-dramatic shows. The performer plays himself or herself and does not assume someone else's character.

Periaktos (A/V)
Triangular piece of scenery that can be turned on a swivel base.

Peripheral (computer)
Any hardware device connected to a computer, such as a monitor, keyboard, printer, plotter, disk or tape drive, graphics tablet, scanner.

Permanent Swap File (computer/Windows)
One of the two kinds of files used for virtual memory. A permanent swap file provides faster performance than a temporary swap file, but it has the disadvantage of using disk space even when Windows is not running.

Permission (computer/Windows)
Rule associated with an object, usually a directory, file, or printer, to regulate which users can have access to the object and in what manner (see also "Right").

Persistence (A/V, computer)
In a CRT (cathode ray tube - screen), the length of time a phosphor dot remains illuminated after it has been energized. Long-persistence phosphors reduce flicker, but generate ghost-like images that linger on screen for a fraction of a second.

Persistent (computer/Windows)
Windows graphic image that survives movement, re-sizing, or overwriting of the window in which it appears. Persistent images are stored in global memory blocks and are not released until the window containing them is destroyed.

Personal Computer
Synonymous with microcomputer, a computer that is functionally similar to larger computers, but serves only one user. It is used for almost all applications traditionally performed on larger computers. With the addition of a modem, a personal computer becomes a terminal to the outside world, capable of retrieving information from other computers and information utilities. There are a wide variety of personal computers on the market, priced from $300 to over $10,000. The size of the computer is based on its memory and disk capacity. Its speed is based on the CPU that runs it, and its visual quality is based on the resolution of its display screen and printer. All newer PCs can now be multitasking machines, which run more than one program concurrently.

Personal Groups (computer/Windows)
For Windows Networking Advanced Server, user profile created by an administrator and assigned to one user. A personal user profile retains changes the user makes to the per-user settings of the Windows Networking environment, and re-implements the newest settings each time the user logs on at any Windows Networking workstation (see mandatory user, user profile).

Personal Information Manager (computer)
Productivity software that can help users cope with calendars, planning, scheduling.

Personal Windows Directory (computer/Windows)
Directory, usually located on the user's hard disk, that contains the Windows files that were loaded to the users system, when the user ran the Windows Setup routine.

Perspective (A/V)
In audio terms, the sound perspective; far sound must go with far picture, close sound with close picture. In video terms, all lines converging in one point.

PERT (computer)
Program Evaluation and Review Technique: an older style planning, scheduling, and control procedure based upon the use of time-oriented networks which reflect the interrelationships and dependencies among the project tasks (activities). The main objective of PERT is to give management improved abilities to develop a project plan and to properly allocate resources within overall program time and cost limitations: also, to control the time and cost performance of the project, and to re-plan when significant budget changes occur.

PgDn Key (computer)
Key on the keyboard used to advance the document one full screen.

PgUp Key (computer)
Key on the keyboard used to back up to the previous screen; previous document page.

Phase (communications, computer/photonics)
Fractional part of a period through which the time variable of a periodic quantity (alternating current, vibration, frequency) has moved, as measured at any point in time from an arbitrary time origin. In Audio/Visual terms, the timing relationship between two signals usually, but not necessarily, of the same frequency. Also used as a term to level the hue control on professional video color monitors. In opto-electronics, that part of the cycle that a light wave is in. With coherent light, the phase relations between different beams decides how they will interfere.

Phase-Angle Measurement (communications, computer)
Determination of the relative times at which alternating current and voltages in a circuit take on zero values. The common phase meter, a device for determining the angle between current and voltage, can be used when its presence will not disturb the circuits under measurement.

Phase Change Recording (computer/photonics)
An optical recording technique using a laser to alter crystalline structure of a metallic surface. The crystal is altered to create a bit that reflects or absorbs light when the bits are read.

Phase Conjugate Mirror (microelectronics/photonics)
Mirror that reverses a light wave falling on it, rather than reflecting the wave.

Phased Conversion (computer)
Term for a systems conversion method in which the new system is phased in gradually.

Phase Encoding (computer)
Magnetic recording technique used for high-speed devices that records a 0 bit as a split negative-positive sequence and a 1 bit as a positive-negative sequence.

Phase Filter (microelectronics/photonics)
Spatial filter that changes the spatial phase modulation of a beam of light passing through it. It does not change the spatial amplitude modulation.

Phase Inverter (communications, computer)
Circuit having the primary function of changing the phase of a signal by 180 degrees: it is most commonly employed as the input stage for a push-pull amplifier.

Phase Locked (A/V, communications, computer)
Technique for maintaining synchronization in an electronic circuit. The circuit receives its timing from input signals, but also provides a feedback circuit for synchronization.

Phase-Locked Loops (communications, computer)
Electronic circuits for locking an oscillator in phase with an arbitrary input signal. A phase locked loop (PLL) is used in two different ways: (1) as a demodulator, where it is employed to follow and demodulate frequency or phase modulation; (2) to track a carrier or synchronizing signal which may vary in frequency with time.

Phase Modulation (PM) (communications)
Transmission technique that modulates (merges) a data signal into a fixed carrier frequency by modifying the phase of the carrier wave. it is a special kind of angle modulation in which the linearly increasing angle of a sine-wave carrier has added to it a phase angle that is proportional to the instantaneous value of the modulating wave (to be communicated) (contrast with AM and FM techniques for modulating a carrier).

Phase-Modulation Detector (communications, computer)
Device which recovers or detects the modulating signal from a phase-modulated carrier.

Phase Modulator (communications, computer)
Electronic circuit that causes the phase angle of the modulated wave to vary (with respect to the unmodulated carrier) in accordance with the modulating signal.

Phase-Shift Keying (communications)
Modulation in which the phase of the carrier signal is shifted to represent digital pulsing.

Phosphor (A/V, computer)
Rare earth material that is used to coat the inside face of a CRT. When struck by an electron beam, the phosphor emits a visible light for a few milliseconds. In color displays, red, green and blue phosphor dots are grouped as a cluster.

Photo CD (A/V, computer)
Trademark of Eastman Kodak for its CDs that provide copies of photographic color images in a format compatible with CD-I and CD-ROM XA drives. Photo CDs are produced from 35-mm film images by licensed photofinishing facilities. These facilities have equipment that can write to the special Photo CD media. The Photo CD media is rewritable. Additional images and, ultimately, sound may be added to the special CD media. A special CD-ROM XA player is required to read subsequent additions to a Photo CD ROM. Photo CD-ROMs with added material are said to have "multiple sessions".

Photoacoustic Spectroscopy (communications, computer, photonics)
Technique for measuring small absorption coefficients in gaseous and condensed media, involving the sensing of optical absorption by detection of sound.

Photochromic Effect (microelectronics/photonics)
Change of color, and thus also of absorption, as a result of illumination.

Photocomposition (computer/printing)
The composition of a printed page using electrophotographic machines, such as phototypesetters and laser printers.

Photoconductive Cell (microelectronics, photonics)
Device used for detecting electromagnetic radiation (photons) by variation of the electrical conductivity of a substance (a photoconductor upon absorption of the radiation by this substance). Photoconductive cells are made from a variety of semiconducting materials in the single-crystal or polycrystalline form.

Photoconductivity (microelectronics, photonics)
Increase in electrical conductivity caused by the excitation of additional free charge carriers by light of sufficiently high energy in semiconductors & insulators. Applications where photoconductivity plays a central role are television cameras with vidicon tubes; normal silver halide emulsion photography; and electrophotographic reproduction.

Photodiode (microelectronics, photonics)
Semiconductor two-terminal component with electrical characteristics that are light-sensitive. All semiconductor diodes are light-sensitive to some degree, unless enclosed in opaque packages, but only those designed specifically to enhance the light sensitivity are called photodiodes. They are used, both, to detect the presence of light and to measure the light intensity of a source.

Photoelectricity (microelectronics, photonics)
Process by which electromagnetic radiation incident on a solid, liquid, or gas liberates electrical charge, which is detectable in an electrical field.

Photoemission (microelectronics, photonics)
Ejection of electrons from a solid (and less commonly from a liquid) by incident electromagnetic radiation. It is also called the external photoelectric effect.

Photoferroelectric Imaging (microelectronics, photonics)
Process of storing an image in a ferroelectric material by utilizing either the intrinsic or extrinsic photosensitivity in conjunction with the ferroelectric properties of the material. It is a process of storing photographic images or other optical information in transparent lead lanthanum zirconate titanate (PLZT) ceramics.

Photographic Lighting Principle (A/V)
In Audio/Visual production, the triangular arrangement of key, back, and fill lights, with the back light opposite the camera and directly behind the object, and the key and fill lights on opposite sides of the camera, and the front and side of the object. The term that is also used, in production, is triangle lighting.

Photolithography (computer/printing)
Technique using photomask to imprint a design onto an object. The design of the circuit paths and electronic elements on a chip are transferred onto a wafer's surface using this method. A photomask is created with the design for each layer of the chip. The wafer is coated with light-sensitive film and is exposed to light shining through the photomask. The light reaching the wafer hardens the film, and when the wafer is exposed to an acid bath (wet processing) or hot ions (dry processing), the unhardened areas are etched away.

Photomask (computer/microelectronics)
Square, flat glass substrate, coated with a photographic emulsion or a very thin layer of metal, on which appear several hundred circuit patterns (each containing thousands of images). The patterns are exposed onto semiconductor wafers.

Photomultiplier (microelectronics, photonics)
Very sensitive vacuum-tube detector of light or radiant flux containing a photocathode which converts the light to photoelectrons (capable of detecting single photons).

Photon (microelectronics, photonics)
Quanta of light: an elementary particle of light; much smaller than its electron counterpart and can thus allow even greater miniaturization within photonic circuits.

Photonics (microelectronics, photonics)
The science of building machine circuits that use light instead of electricity. The science of light-sensitive computing. Photonic computing, as opposed to electronic computing, involves light as the on-off, logic medium. Photonics research currently points toward faster, three-dimensional, and miniaturized computing in the future.

Photooptic Memory (computer, photonics)
A storage device that uses a laser beam to record data onto a photosensitive film.

Photorealistic Image Synthesis (computer/graphics)
In computer graphics, format for describing a picture that depicts actual realism of the image; includes attributes as surface texture, light sources, motion blur and reflectivity.

Photoreceptor (A/V, computer)
Light-sensitive semiconductor creating an electrical charge in proportion to the amount of light striking its surface. Video cameras use arrays of these to create video signals.

Photorefractive Effect (microelectronics/photonics)
Change of the index of refraction as a result of illumination.

Photoresist (microelectronics, photonics)
Light-sensitive film in photolithography that temporarily holds the pattern to be etched away. The processing materials are light sensitive and are deposited as a uniform film on a wafer of substrate. The exposure of a specific pattern is performed through masking operations and techniques.

Phototransistor (microelectronics, photonics)
Semiconductor device with electrical characteristics that are light-sensitive. Phototransistors differ from photodiodes in that the primary photoelectric current is multiplied internally in the device, thus increasing the sensitivity to light.

Phototube (microelectronics, photonics)
Electron tube containing a photocathode from which electrons are emitted when it is exposed to light or other electromagnetic radiation.

Phototypesetter (computer/printing)
Device that creates professional quality text. Input to the phototypesetter comes from the keyboard, over a communications channel or via disk or tape. The output is a paper-like or transparent film that is processed into a camera-ready master for printing. Advanced industrial machines generate the actual printing plates. Phototypesetters employ various light technologies for the creation of the characters. Older machines use a spinning film strip that is used as a photomask for a particular font. Light passing through the film strip is enlarged by lenses to the appropriate type size, exposing the film. Other machines create images on CRTs that are used to expose the film, and the latest units use lasers to generate the image directly onto the film like a laser printer. The phototypesetter has been used to print books, magazines and all commercially printed materials, and was originally the only machine that could handle multiple fonts and text composition capabilities, such as kerning. Today, desktop laser printers are being used to typeset text, and although they can't produce the ultra-fine lines of the high-resolution (1,200 to 2,400 dots per inch) phototypesetters, they can produce excellent print.

Photovoltaic Cell (microelectronics, photonics)
Device that detects or measures electromagnetic radiation by generating a current or a voltage, or both, upon absorption of radiant energy.

Photovoltaic Effect (microelectronics, photonics)
Term most commonly used to describe the production of a voltage in a non-homogenous semiconductor, such as silicon, by the absorption of light or electromagnetic radiation.

Physical Layer (communications, computer)
First Layer of the OSI model concerned with protocols for network security, file transfers, and format functions (OSI = Open System Interconnection).

Physical Record (computing)
Collection of logical records; also called a block: it can also be a hard-copy record.

Piano Roll Sequencer (A/V, computer)
Musical sequencing application displaying the notes to be played as bars. The bar's length represents the note's duration, and its vertical position on-screen represents the note's pitch. The appearance is similar to a player-piano roll rotated 90 degrees.

Pica (computer/printer)
Unit of typographic measurement equal to 12 points (1/6th inch). This unit used to be generally used for horizontal measurement by printers (also a synonym for 12 pitch).

Picon (computer)
Icon representing a still image, animation, or video sequence. The representation is usually a size-reduced version of the original video image.

Picosecond (communications, computer)
One trillionth of one second.

Pickup (A/V)
In Audio/Video production, the sound reception by a microphone.

Pickup Pattern (A/V)
Territory around the microphone within which the microphone can hear well, that is, that the microphone has the optimal desired sound pickup.

Pickup Tube (A/V)
For tube-style cameras the main camera tube that converts light energy into electrical energy, in this case, the video signal coming through the camera tube.

PICT (computer)
Favored graphics file format of the Apple Macintosh computer line. Some Windows graphics applications are capable of reading PICT files from DOS-formatted floppy disks or PICT files downloaded from CompuServe and other information utilities.

Picture Tube (A/V)
Cathode-ray tube used as a television picture tube. Modern television picture tubes usually have large glass envelopes on the inner face of which a light-emitting layer of luminescent materials is deposited (phosphors). A modulated stream of high-velocity electrons is made to scan this layer of luminescent materials in a series of horizontal lines so that it recreates the picture elements (light, dark, colorized areas). The number or electrons in the stream at any instant of time is varied by electrical impulses corresponding to the signal sent out by the television transmitter. These electrical impulses (picture information) are originally generated by a studio television camera. The home television receiver picks up the signal, and after suitable amplification and detection, the picture information is supplied to the picture tube so that it recreates the original picture that was taken by the camera.

Pie Chart (computer)
Pie-shaped graph used to compare values that represent parts of a whole.

Piezolectric (microelectronics)
Generation of electricity from a crystal that is subjected to pressure. Certain crystal oscillators and microphones can be examples of piezoelectric devices.

Piezoelectric Crystal (microelectronics)
Crystalline substance which exhibits the piezoelectric effect. This "pressure electricity" was first positively identified by the Curies in 1880, when they discovered that some crystals produced electric charges on part of their surface when the crystals were compressed in particular directions; the charge disappearing when the pressure was removed. The principal piezoelectric materials used commercially are crystalline quartz and rochelle salt (now being substituted by barium titanate). The basic properties of piezoelectric crystals are used in electromechanical transducers such as ultrasonic generators, microphones, phonograph pickups, and electromechanical resonators such as frequency controlling quartz crystals.

Piezoelectricity (microelectronics)
Electricity, or electric polarity, resulting from the application of mechanical pressure on a dielectric crystal. The application of a mechanical stress produces, in certain dielectric (electrically nonconducting) crystals an electric polarization (electric dipole moment per cubic meter) which is proportional to the stress. If the crystal is isolated, the polarization manifests itself as a voltage across the crystal, and if the crystal is short-circuited, a flow of charge can be observed during the loading. Conversely, application of a voltage between certain faces of the crystal produces a mechanical distortion of the material. This reciprocal relationship is referred to as the piezoelectric effect.

PIF: Program Information File (computer/Windows)
File that provides information about how Windows Networking should run a non-Windows Networking application. PIF's contain such items as the name of the file, a start-up directory, and multitasking options for applications running in "386 enhanced" mode.

Piggy-Backing (communications)
Inclusion of an acknowledgment to a previously received packet in an outgoing packet.

Pigment (computer/printing)
Insoluble coloring material, used as a colorant in printing inks.

Pilot Conversion (computer)
Systems conversion method in which a designated group of users try the system first, before converting the rest of the organization to the new system.

Pilot Program (computer)
Systems development method in which a designated group of users use, test, experiment, with a program before it is implemented: it is often designed to fail: like research and development rather than product development.

Pinhole (computer/microelectronics)
Minute hole through a layer or pattern, in microelectronic fabrication.

PIN Photodiode (microelectronics/photonics)
Simplest semiconductor light devices.

Pipeline Processing (computer)
Category of techniques providing simultaneous or parallel processing within the computer. It refers to overlapping operations by moving data or instructions into a conceptual pipe with all stages of the pipe processing simultaneously. For example, while one instruction is being executed, the computer is decoding the next instruction. In vector processors, several steps in a floating point operation can be processed simultaneously. For example, the "Pentium" Series of microprocessors from Intel incorporated pipeline processing in their chip architecture (sometimes called SuperScaler design, architecture).

Pipeline Processors (computer)
Pipeline (array processors) in a hardware context is a construction technique for achieving higher performance by breaking a complex, time-consuming function into a series of simpler, shorter operations, each of which can then be executed in assembly-line fashion with simultaneous computation on different sets of data.

Piracy (computer)
Stealing or theft of software (illegal copying) without proper licensing.

Pitch (computer/printer)
Characters per inch, when using more traditional, typewriter-style, type faces.

Pitch Bend (A/V, music, M/M)
Continuously alter frequency of a synthesized voice to duplicate vibrato or slide effects.

Pitch Scale Factor (A/V, computer, M/M)
A WaveAudio function scaling the playback rate of a WAVE file.

Pixel (computer)
Picture Element - the smallest element on a video display screen. A screen is broken up into thousands of tiny dots, and a pixel is one or more dots that are treated as a unit. A pixel can be one dot on a monochrome screen, three dots (red, green, and blue) on color screens, or clusters of these dots. For monochrome screens, the pixel, normally dark, is energized to different light intensities, creating a range from dark to light. For color, each red, green, and blue dot is energized to different intensities, creating a range of colors perceived as the mixture of these dots. Black is all three dots off, white is all three dots on, and grays are even intensities of each color. The number of bits assigned to each pixel in its associated digital memory determines the number of shades and colors that can be represented. The most economical system is monochrome in which one bit is used per pixel, either on or off. In the most elaborate color displays, which use up to four full bytes for each of the red, green, and blue dots, each pixel can display billions of different shades. High-resolution screens may use a million pixels. Many megabytes of memory would have to be reserved to hold such an image.

Pixelation (A/V)
Term indicating graininess in a video image. Pixelation occurs when camcorders are operated at very low light levels or an excessive number of generations of images has occurred with digital videotape recorders. Pixelation is often deliberately introduced as a special video effect.

P.L. (A/V)
Abbreviation for Private Line or Phone Line: intercommunication in TV production.

Planar (computer)
Technique developed by Fairchild Instruments used to create the sublayers of a transistor in a chip by forcing chemicals under pressure into the exposed areas. The planar process was a major step in the creation of the microchip. Contrast with the earlier mesa process, which created more deeply etched channels in the semiconductor material.

Planar Process (computer/microelectronics)
Fabrication of monolithic integrated circuits and semiconductor devices using silicon dioxide as a masking agent and producing components on a single plane.

Plane Wave (microelectronics/photonics)
Beam of light whose wavefronts are planar surfaces.

Plasma Display (A/V, computer)
Flat-screen technology that contains an inert ionized gas sandwiched between and x-axis panel and a y-axis panel. An individual dot (pixel) is selectable by charging an x-wire on one panel and a y-wire on the other panel. When the x-y coordinate is charged, the gas in that vicinity glows a bright orange color (also called a gas discharge display).

Platen (computer/microelectronics)
In microelectronic fabrication, the plate which holds substrate during screen printing.

Plating (computer/microelectronics)
Deposition of a metal layer on a substrate surface by electrolytic or other chemical means. Materials include gold, copper, platinum; functions of plating vary, including corrosion protection, solder-ability, etch resistant bonding, and electrical connections.

Platform (computer)
Particular brand or model of a computer. PCs, Macintoshes, and Amigas are platforms: also used to describe what software operating system is being used (DOS, Unix, etc.)

Playback (A/V)
Playing back on a monitor or television receiver of videotape-recorded material through a videotape recorder (in the playback mode).

Playlist (A/V, music)
A group of musical compositions, usually in MIDI format, to be played in sequence. Playlists are commonly implemented by jukebox applications.

Plot (A/V)
In Audio/Visual production, how the story develops from one event to the next.

Plot Area (computer)
Area in which a graph is drawn.

Plot Bed (computer)
Flatbed Area on a Flatbed Plotter (size) where the paper is inked.

Plotter (computer/printer)
A graphics printer that draws images with ink pens. Plotters require data in vector graphics format, which makes up an image as a series of point-to-point lines.

Plotter Font (computer)
Font created by a series of dots connected by lines. Plotter fonts can be scaled to any size and are printed on plotters. Some dot-matrix printers also support plotter fonts.

Plug Compatible (computer term)
Hardware that is designed to perform exactly like another product. A plug compatible CPU is a computer that runs the exact same software as the machine it's compatible with. Plug compatible peripherals can work the same as the device they are replacing.

Plumbicon (A/V)
Trademark name for a lead oxide video camera tube made in Holland and the United States, whose principal distinguishing characteristics are high sensitivity and low lag.

PMD (communications/photonics)
Physical Media-Dependent layer of the Fiber Data Distributed Interface in fiber-optic cabling (FDDI, and part of the CCITT specification for FDDI).

PMOS (computer/microelectronics)
P-channel MOS (Metal Oxide Semiconductor): refers to the oldest type of MOS circuit where the electrical current is a flow of positive charges.

Point (computer/printing)
Typographic measurement equalling approximately 1/72nd of an inch (1/12th of pica).

Point And Shoot (computer)
To select a menu option or activate a function by moving the cursor onto a line or object and pressing the return key or mouse button.

Point-Contact Diode (microelectronics)
Early, older-usage semiconductor rectifier using the barrier formed between a specially prepared semiconductor surface and a metal point to produce the rectifying action. Point-contact diodes have been widely used in radio and television, and most notably in computers, microwave detectors, and ultrahigh-frequency mixers. Today their use is very limited, having been replaced by junction diodes and Schottky barrier diodes.

Pointer (computer)
Also referred to as data pointers or program counters, a data type that comprises a number representing a memory location. Near pointers are constrained to the 64-K default, local data segment. Far pointers can access any location in the computer's memory. Pointers are used in C language to access elements such as arrays, strings, and structures. The term is also sometimes used in place of the term, cursor - an indicator on the screen that shows where the next user interaction will be.

Point Of Sale (computer)
Capture of data at the time and place of sale. Point of sale systems use personal computers or specialized terminals that are combined with cash registers, optical scanners for reading product tags, and/or magnetic stripe readers for reading credit cards. Point of sale systems may be online to a central computer for credit checking and inventory updating, or they may be stand-alone machines that store the daily transactions until they can be delivered or transmitted to the main computer for processing.

Point Spread Function (microelectronics/photonics)
Response (output) of a linear shift invariant system presented with a impulse input.

Point-To-Point (communications)
Term sometimes used to describe a direct connection between two computers or devices.

Poisson Distribution (communications)
When the average transaction volume in a communications system can be estimated, Poisson distribution can be used to determine the probable minimum and maximum number of transactions that can occur within a given time period. Poisson distribution, as a statistical method was developed by the 18th century French mathematician S.D. Poisson and it is often used for predicting the probable distribution of a series of events.

Polarity (computer)
Direction of charged particles, which determines the binary status of a bit.

In micrographics, the change in the light to dark relationship of an image when copies are made. Positive polarity is dark characters on a light background; negative polarity is light characters on a dark background.

Polarity Reversal (A/V)
Reversal of the grayscale; the white areas in the picture become black and the black areas white, as the film negative is to the print.

Polishing (computer/microelectronics)
Mechanical finishing operation conducted upon solid state substrates to achieve smoothness and the desired surface qualities (see Lapping).

Poll And Select (communications)
Process by which a primary station invites (polls) secondary stations, one at a time, to transmit, and by which a primary station requests that a secondary station receive data (select).

Polling (communications)
Technique that determines when a terminal is ready to send data. A computer continually interrogates all of its attached terminals in a round robin sequence. If a terminal has data to send, it sends back an acknowledgement and the transmission begins. Contrast this with interrupt-driven, in which the terminal generates a signal when it has data to send.

Polychromatic (microelectronics/photonics)
Light composed of waves of many different frequencies, and thus, many different colors.

Polymorphic Tweening (computer)
Animation technique that, based on information about its starting and ending shapes, creates the necessary "in-between" steps to change one object into another.

Pop Filter (A/V)
Bulblike attachment (permanent/detachable) on front of the microphone that filters out sudden air blasts, such as explosive consonants (p's, t's, k's) delivered directly into the microphone.

Pop-Up Program (computer/Windows)
Memory-resident program that can be activated while another program is running

Porcelainize (computer/microelectronics)
Coat and fire a metal with glass material, forming a hybrid circuit substrate.

Port (communications, computer)
External connector on a computer used to connect a modem, printer or other device. On a front end processor, a port connects to a communications line or modem. The ports specified on a personal computer, such as 2 serial, 1 parallel, refer to external connections, however, the computer has several internal expansion slots that accept control units for devices (disks, soundboards, modems. As a verb, describes an application designed for one type of computer, to port to another, as in porting a product from DOS to Unix. In microprocessor terms, connections that provide a path between the microprocessor and the outside world.

Port Expander (communications, computer)
Device that connects several lines to one port in the computer. A line is given access to the port either by a hardware switch or through software selection.

Portability (computer)
Software is said to be portable if it can, with reasonable effort, be made to run on computers other than the one for which it was originally written. Portable software proves its worth when computers are replaced, or when the same software is run on may different computes, whether widely dispersed or at a single site.

Portrait Mode (computer/printer)
One of two printing modes on most printers (the other is landscape mode). In portrait mode, printed lines run perpendicular to the paper's direction of travel through the printer.

Portrait Orientation (computer/printer)
Information is presented across the narrow side of the form (normal 8.5 x 11).

Ports (A/V)
In Audio production, the slots in the microphone that help to achieve a specific pickup pattern and frequency response. In video production, plugs or patches in a multiplexer for multiples of various video sources.

Positive (computer/printing)
Photographic reproduction in which the tonal values correspond to the original.

Positive Logic (computer/microelectronics)
Logic in which the more positive voltage represents the "1" stage (see binary logic).

POSIX (computer)
Portable Operating System Interface for Unix - IEEE standard defining language interface between application programs and the UNIX operating system. Adherence to the standard ensures compatibility when programs are moved from on UNIX computer to another.

PostScript (computer/printers)
Page description language from Adobe Systems, Inc, that is used in a wide variety of printers. Software that provides PostScript output is able to print text and graphics on any PostScript printer or imagesetter. PostScript printers have a built-in interpreter that translates PostScript instructions into the printer's machine language, generating the required dot patterns. Fonts are scaled to size by the interpreter, eliminating the need to store a variety of font sizes on disk.

Posterization (A/V)
Also called solarization; a visual effect that reduces the various brightness values to only a few (usually three or four) and gives the image a flat, poster-like effect.

Postproduction (A/V)
Production activity that occurs after the production: usually refers to either editing of film or videotape, or to post-scoring and mixing sound for later edition to picture portion.

Postproduction Editing (A/V)
Assembly of recorded material after the actual production.

Pot (A/V)
Abbreviation for potentiometer used in A/V production as a sound-volume control.

Potentiometer - Variable Resistor (microelectronics)
Device with three terminals used in electric circuits; the two ends of a resistor, and a movable connection, allowing adjustment of resistance between this movable connection and either end connection. A potentiometer is used to adjust and control the electric potential difference (voltage) applied to some device or part of a circuit. The output voltage may be varied from zero to the value of the input voltage. Examples of its use are as a field-current control on an electric generator and as a volume control on a radio.

Potentiometer - Voltage Meter (microelectronics)
Device for the measurement of an electromotive force (emf) by comparison with a known potential difference. The known potential difference is established by the flow of a definite current through a known resistance, using a standard cell as a reference.

POTS (communications)
Plain Old Telephone Services: traditional telephone services from a common carrier.

Power Amplifier (A/V, communications)
Final stage in multistage amplifiers, such as audio amplifiers and radio transmitters, designed to deliver appreciable power to the load. They can be called upon to supply power ranging from a few watts in an audio amplifier to many thousands of watts in a radio transmitter. In audio, the load is usually the dynamic impedance presented to the amplifier by a loudspeaker, the challenge is to maximize power delivered to the load over a wide range of frequencies.

Power Down (computer)
Turn off the computer in an orderly manner by making sure all applications have been closed normally and then shutting the power off. Powering down can include backing out of the programs, applications (Windows layers, etc.) in an orderly manner.

Power Supply (computer/printer)
Electrical system that converts AC (alternating current) from the electrical wall outlets into the DC (direct current) required for the computer circuitry.

PPI (computer/printer)
Pixels Per Inch, a measure of a device's resolution.

PPM (computer/printer)
Pages Per Minute - measures the speed of a printer, such as a laser printer (i.e.8 PPM).

PPQN (A/V, computer)
Pulses Per Quarter Note. PPQN is the measure of resolution of a MIDI timing signal. The standard MIDI clock messages occur at 24 PPQN (32nd-note triplets). At 120 beats per minute (BPM) in 4/4 time, 48 MIDI clock messages per second are transmitted.

Preamp (A/V)
In A/V production, an abbreviation for preamplifier. Weak electrical signals produced by a microphone or camera pickup must be strengthened by a preamplifier before they can be further processed, manipulated, and amplified to normal signal strength.

Preamplifier (A/V, communications)
Voltage amplifier suitable for operation with a low-level input signal. It is intended to be connected to another amplifier with a higher input level. Preamplifiers are necessary when an audio amplifier is to be used with low-output transducers such as magnetic phonograph pickups. A preamplifier may incorporate frequency-correcting networks to compensate for the frequency characteristics of a given input transducer and to make the frequency response of the preamplifier-amplifier combination uniform.

Precedence (computer)
Execution sequence of operators in statements containing more than one operator.

Precision (computer)
For a numeric representation system that employs strings of symbols from a finite alphabet to represent numbers, the precision attribute of a symbol string denotes the length of the string, and possibly also positional information for determining a base point of the string. Those numbers, representable by finite length symbol strings, are termed the finite precision numbers of that numeric representation system.

Premastering (A/V, computer)
Process of creating a sample CD-ROM for review before creating the master disc for production quantities of CD-ROMs. Premastered samples are created on CD-WO drives.

Preroll (A/V)
Start a videotape and let it roll for a few seconds before it is put in the playback or record mode in order to give the electronic system time to stabilize.

Presentation Graphics (computer)
Business graphics (bar charts, graphs) used as presentation material in meetings. It implies a set of business graphics that employs artistic type fonts and stylized graphics, such as 3-D charts (i.e. Project by Windows, Presentation by WordPerfect, etc.)

Presentation Layer (communications)
Sixth Layer of the ISO/OSI Model (International Standards Organization) concerned with protocols for network security, file transfers, and format functions.

Preset Board (A/V)
Program device into which several lighting setups (scenes) can be stored, and from which they can be retrieved, when needed.

Preset Monitor (A/V)
Also called PST monitor: a special preview monitor used by the technical director for checking and adjusting special effects.

Pressure Zone Microphone: PZM (A/V)
Microphone mounted on a reflecting surface to build up a pressure zone at which all the sound waves reach the microphone at the same time: ideal for group discussions.

Preview Bus (A/V)
In Audio/Visual production, the rows of button that can direct an input to the preview monitor at the same time another video source is on the air.

Preview Monitor (A/V)
Monitor that shows a video source, except for the line (master) and off-the-air monitors. Also, a monitor that shows the director the picture intended to be used in the next shot.

Primary Colors (computer/printer)
Set of colors that can be mixed to produce all colors in a color space; in additive systems they are Red, Green, Blue; in subtractive systems they are Cyan, Magenta, Yellow.

Primary Memory (computer)
Term sometimes used to describe electronic memory that temporarily holds data and program instructions needed by the Central Processing Unit (CPU). It is also called memory, primary storage, main storage, internal storage, and main memory.

Primary Partition (computer/Windows)
Portion of a physical disk that can be marked for use by an operating system. There can be up to four primary partitions (or up to three, if there is an extended partition) per physical disk. A primary partition cannot be sub-partitioned.

Primary Storage (computer)
Term sometimes used to describe the electronic circuitry that temporarily holds data and program instructions needed by the Central Processing Unit (CPU). It is also called memory, primary memory, main storage, internal storage, and main memory.

PRINT (computer/DOS)
DOS Command that prints text files in the background so that the user can continue doing other tasks. This command is not intended to print data files that are created with other applications, since most applications will have more advanced print features, and many data files include special characters that will cause unexpected results using PRINT.

Print Command (computer/printer)
Command that can provide options for printing a page of text or a spreadsheet.

Printed Circuit (microelectronics)
Generic term applied to circuits fabricated by any of several graphic art processes. Printed circuits greatly simplify mass production and increase equipment reliability. Their most important contribution, however, is the tremendous reduction achieved in size and weight of electronic devices. Printed circuits are used in practically all types of electronic equipment, radio and TVs, telephone systems, control systems. The different classes of printed circuits include: (1) printed wiring; (2) thick and thin films; (3) hybrid circuits; (4) integrated circuits.

Printed Circuit Board (microelectronics)
Flat board that holds chips and other electronic components. The back side is "printed" with electrically conductive pathways between the components. the printed circuit board of the 1960s connected discrete (elementary) components together. The printed circuit board of the 1990s connects chips together, each chip containing hundreds of thousands of elementary components.

Printer Cartridge Metrics File: PCM (computer/printer)
File that contains Printer Fonts Metrics files for each font on a font cartridge.

Printer Driver (computer/printer)
Software routine that converts an application program's printing request into the language that the printer understands. In Windows, a program that translates generic GDI information into the language understood by a specific printer. The user must use Control Panel to install a printer driver before Windows can use the particular printer.

Printer Font Metrics File: PFM (computer/printer/Windows)
Supplies a Windows printer driver with information about a font, such as family, point size, widths of individual characters, and more.

Printing Plate (computer/printer)
Surface, usually metal, rubber, or plastic, that has been treated to carry an image.

Printer Window (computer/Windows)
Shows information for one of the printers installed or that are connected to the system. For each printer, documents that are waiting to be printed can be seen on a queue, who owns them, how large they are, and other information.

Print Queue (computer/Windows)
One or more jobs waiting to be sent to a specific printer. When the user sends files to the printer faster than they can be printed, Print Manager maintains a print queue of all jobs that haven't yet reached the printer.

Print Server (computer, communications)
Computer assigned on the network to control one or more printers. It stores the print image output from the users of the system and feeds it to the printer a job at a time. The print server function can be added to a network server that provides other file sharing.

Print Spooler (computer/printer)
Software the creates a buffer where files to be printed are stored while waiting to print.

Print Zone (computer/printer)
Area on paper where a printer creates an image. For most laser printers and dot-matrix printers, this area is maximum 8 inches wide. the vertical dimension is unlimited for dot-matrix printers and is usually 13.5 inches for a laser printer with legal-size paper capabilities.

Prism Block (A/V)
Compact, internal optical system of prisms and filters that separate white light into the three primary colors (Red, Green, Blue).

Private Line (communications)
Dedicated line leased from a common carrier: a line dedicated to one customer.

Privacy Systems (communications)
Devices/methods used to ensure privacy of long-distance & overseas telephone calls. This can be accomplished in a variety of ways. The first method employs equipment for inverting speech to make telephone conversations unintelligible to the casual listener. At one end devices change the speech-conveying signal, making high frequencies low and low frequencies high, for example. At the other end, synchronized equipment restores the inverted speech to its original form for delivery to the listener. The other method employs filters to separate the transmitted speech signal into several narrow-frequency bands. Each of these is then treated differently in a prearranged manner, the relative position of individual portions of the signal being interchanged in the frequency spectrum by inversion and transposition (also encryption).

Privileged Instruction (computer)
Improper use of certain instructions can easily affect system integrity in a multiuser environment. In order to prevent accidental or intentional abuse of these instructions, many computers have a special privileged mode in which instructions, called privileged instructions, can be executed. In a processor that possesses such a mode, the instructions are divided into sets; each set can be executed in its own mode.

Probing (computer/microelectronics)
In microelectronics fabrication, term used to describe electrical testing that employs very finely-tipped probes applied sequentially to each of the finished "dice" of a wafer.

Problem Oriented Languages (computer)
In general, any programming language that helps solve problems, also known as applications-oriented or special purpose programs. Some languages have been designed for very special applications such as numerical control programming or electronic circuit analysis. Others are applications oriented, but at the same time are more general purpose.

Procedure (computer)
Self-contained statements in source code assigned a name and executable as an entity. Also, a procedure is a portion of a high-level language program which performs a specific task necessary for that program. The term is normally used interchangeably with the terms sub-program and subroutine when referring to high-level languages, although the term subroutine has a wider meaning outside high-level languages.

Procedure Oriented Languages (computer)
Language that expresses commands to a computer in a form somewhat similar to such natural languages as English and mathematics. It is distinguished from machine language and assembly language, and problem-oriented language. It is also distinguished from list-processing and string-processing languages which do not express procedures or problems, but which are different since the information processed is almost entirely symbolic.

Process (computer)
Element of a data flow diagram that represents actions taken on data: comparing, checking, stamping, authorizing, filing, etc.

Process Box (computer)
In flowcharting, a rectangular box that indicates an action to be taken.

Processing Amplifier (A/V)
In Audio/Visual production, the portion of a video camera used to modify the camera signal in areas such as white level, black level, gamma, and color balance, as well as amplifying the signal to a level that is useable by the remaining elements of the video system. Processing Amplifiers can also be external to the camera but supporting similar video processing requirements (camera control unit) (sometimes abbreviated to "Proc Amp").

Process Message (A/V)
Interaction between the percipient and the audio/visual stimuli of the television program.

Process Shot (A/V)
Photographing foreground objects against a usually moving background projection.

Producer (A/V)
Creator and organizer of the show, film; usually in charge of financial matters. Also, the person in overall command and with overall responsibility for all elements.

Production (computer)
Rule (rule of inference) in a grammar that describes how parts of a string ( word, phrase, construct) can be replaced by other strings. The set of productions of a grammar describe all the rules by which strings of the language can be generated by the grammar.

Production Switcher (A/V)
Audio/Video switcher located in the studio control room or remote van.

PROFS (computer)
Professional Office System – an older proprietary program from IBM that runs in a VM mainframe environment. It provides an electronic mail facility for text and graphics, a basic type of library service for centrally storing text, electronic calendars and appointment scheduling, and it allows document interchange with DISOSS users.

Program (A/V, computer, M/M)
Complete sequence of computer instructions necessary to solve a specific problem, perform a specific action, or respond to external stimuli in a prescribed manner. A collection of instructions that tell the computer what to do. Program, software and instructions are synonymous. Programs are written in program language and converted into the computer's machine language by software called assemblers and compilers.

Application Programs are programs that organize information but do not instruct the computer to do everything. When application programs need input or are ready to output data, they send a request to the operating system, which contains the actual instructions to perform those activities. The operating system performs the task and turns control back to the application program (i.e. Access, Excel, Office, Word, WordPerfect are application programs).

In MIDI, a numbered definition of a combination of instrument voices and their MIDI channel assignments, volume levels, and other parameters chosen by the manufacturer of the synthesizer. This definition is similar to a user-defined record in computer programming. Programs, also called patches, are stored in synthesizer memory and selected by MIDI program change messages.

Program Bus (A/V)
In Audio/Video production, the bus on a switcher whose inputs are directly switched to the line-out (also called the direct bus).

Program Counter (computer)
CPU register containing the address of the next instruction to be fetched and executed.

Program File (computer/DOS/Windows)
File that starts an application or program. A program file can have filename extensions such as: .EXE, .PIF, .COM, .BAT.

Program Group (computer/Windows)
In Program Manager, a collection of applications. Grouping applications makes them easier to find (in a group) in order to start them, individually.

Program Information File: PIF (computer/Windows)
File that provides information about how Windows Networking should run a non-Windows Networking application. PIF's contain such items as the name of the file, a start-up directory, and multitasking options for applications.

Program Item Icon (computer/Windows)
Application accessory, or document represented as an icon in a group window.

Program Speaker (A/V)
Loudspeaker in the control room carrying program sound; its volume can be controlled without affecting the actual line-out program feed (also called audio monitor).

Programmer (computer)
In computing, the programmer is the link between a problem or process to be computerized and its successful realization on the computer. In the fullest meaning of the term, the programmer will participate in the definition and specification of the problem itself, as well as the algorithms to be used in its solution. He/She will then design the more detailed structure of the implementation, select the most suitable language, write and debug the necessary programs, and provide clear documentation for both the user and other programmers who may modify the program.

Programmer/Analyst (computer)
Individual who may perform systems analysis functions in addition to programming.

Programming Language (computer)
Assembler language (low-level language), the first programmer language, eased the communication between programmers and machines by permitting symbolic rather than numeric or positional (machine code) references for operation codes and addresses. Added data and instruction could therefore be added to a program without changes to existing instructions. High-Level languages allow programmers to communicate more easily by providing structures that hide the architecture of the machine. Expressions in high-level languages can be written almost as they are, in say algebra, so that the programmer need not worry about which register contains a particular computation or which registers are available. Higher level control structures like IF, THEN, ELSE, WHEN statements make it easier to see the overall structure of a program than do lower-level branch instructions. The High-level programming language used for the DOS Operating System, for example, is called BASIC. The programming language used for Unix and Unix derivations, for example, is called "C". The High-level language for the new WindowsNT Operating System is C++, a more compact and more efficient, some say a more mature "C". Others that have developed over time for different types of computing applications include: ADA, ALGOL, APL, COBOL, FORTRAN, LISP, PASCAL, PL/1, RATFOR, SNOBOL, and others.

Program Language Semantics (computer)
Term used in computer science to refer to the meanings of the symbol strings of a language. A program in a programming language is represented by a symbol string, but denotes a sequence of instructions to be executed by a computer. The symbol string is a syntactic representation of the program. Semantics associates meanings with syntactic program representations, although, there are several alternative ways of doing this.

Program Libraries (computer)
For a computer, a program library can be a collection of programs for a particular use or application. These libraries contain programs for the solution of differential equations, for analysis of variance, for numerical integration, and other statistical applications.

Progressive Proofs (computer/printing)
Set of press proofs that includes the individual process colors, plus overprints of two, three, and four-color combinations in their order of printing.

Projection Television System (A/V)
Projector that takes composite or component input from and audio/visual source and projects the image, using special lenses, onto a wall or screen up to 10 feet diameter (depending on the quality of the projection unit). Different technologies include Liquid Crystal Display Panels within the projector (Red, Green, Blue), as well as oil-based "light valve" projection techniques (range of prices from $2,000 to over $40,000).

PROM (computer)
Programmable Read Only Memory: ROM into which the user can write information.

Prompt (computer)
Signal that the computer or an operating system is waiting for data or a command.

PROMPT (computer/DOS)
DOS Command that changes the appearance of the DOS command prompt that prompts the user for the next command that the user would want to perform.

Proofs (computer/printing)
Hard-Copy sample designed to show how an image or document will appear when printed.

Propagation Delay (computer/microelectronics)
In microelectronic fabrication terms, a measure of the time required for a change in logic level to be transmitted through an element or a chain of elements.

Propagation Time (computer/microelectronics)
In microelectronic fabrication terms, the time necessary for a unit of binary information (high voltage or low voltage) to be transmitted or passed from one physical point in a system or subsystem to another: for example, from the input of a device to the output.

Property (computer)
Other principal characteristic of objects (first is methods). Properties may be defined for an object or for the class of objects to which the particular object belongs. If the latter occurs, the properties are said to be inherited.

Proportionally Space Font (computer/Windows)
Font in which some characters are wider than other characters. Proportionally spaced fonts produce a typeset appearance (contrast with Monospaced Font).

Props (A/V)
Properties: furniture and other objects used for set decorations by actors/performers.

Prosumer (A/V)
Contraction of professional and consumer. Prosumer sometimes describes A/V components such as camcorders and VCRs, bridging the gap between consumer-grade products and industrial-quality devices. Prosumer video equipment is usually capable of being remotely controlled by a computer or edit controller.

Protected Mode (computer/DOS/Windows)
Operating mode of a computer that is capable of addressing extended memory directly.

Protocol (communications)
Set of rules and regulations that govern the transmitting and receiving of information. Also, a set of specifications that describes the rules and procedures that products should follow to perform activities on a network. Protocols provide some help to enable products from different vendors to communicate on the same network.

Prototyping System (computer/microelectronics)
Hardware system used to bench-test ("breadboard") a microprocessor-based product.

Pseudo-Duplexing (communications)
Communications technique that simulates full-duplex transmission in a half-duplex line by turning the line around very quickly.

PSTN (communications)
Public Switched Telephone Network - the worldwide voice telephone network.

PTT (communications)
Postal, Telegraph & Telephone: government controlled agency in many European countries that controls postal, telegraph, and telephone services (common service).

P-Type Semiconductor (computer/microelectronics)
Extrinsic (outward side) semiconductor in which the hole density exceeds the conduction electron density. An electron acceptor type.

PU: Physical Unit (communications, computer)
Representing a tangible unit, devices, under IBM's SNA such as a terminal or intelligent controller (SNA = System Network Architecture).

Public Domain Software (computer)
Software that is free and not copyrighted.

Pull Focus (A/V)
A/V term to describe an on-air focusing adjustment technique involving the foreground and background of the scene whereby sharp focus is shifted from one to the other.

Pulse (computer/microelectronics)
Signal of very short duration.

Pulse-Code Modulation: PCM (communications, microelectronics)
Pulse-code modulation, invented by H.A. Reeves in 1939, is a method of transmitting continuously varying message waves in which: (1) the message wave is sampled; (2) the value of each sample is replaced by the closest one of a finite set of permitted values; (3) these permitted values are then each unambiguously represented by choosing one of the possible patterns of on-or-off pulses. These three operations are known as sampling, quantizing, and coding, respectively. Examples are: Electronic Switching Systems, Optical Fiber transmission systems, Nationwide digital transmission PCM systems.

Pulse-Count System (A/V)
In Audio/Visual production a term sometimes used to describe types of address code systems used to identify exact locations on the videotape. It counts the control track pulses and translates this count into elapsed time and frame number (see SMPTE).

Pulse Generator (computer/microelectronics)
Electronic circuit capable of producing a waveform that rises abruptly, maintains a relatively flat top for an extremely short interval, and then rapidly falls to zero. A relaxation oscillator, such as a multivibrator, may be adjusted to generate a rectangular waveform having an extremely short duration, thus referred to as a pulse generator.

Pulse Modulation (communications/microelectronics)
System of modulation in which the amplitude, duration, position, or mere presence of discrete pulses may be so controlled as to represent the message to be communicated. These forms of pulse modulation are commonly called: (1) Pulse-amplitude modulation or PAM; (2) Pulse-code modulation or PCM; (3) Pulse-duration modulation or PDM; (4) Pulse-position modulation, or PPM. Of all the different forms of pulse modulation, PCM is the most outstanding. With PCM, transmission circuits are simplified; overall transmission losses are avoided; crosstalk, interference, and distortion are virtually eliminated; signals may be repeated again and again without accumulating significant distortion; patterns of on-or-off pulses constitute the only type of signals that are propagated, regardless of the type of message to be communicated; in the interest of reliability, no on-or-off pulse can be lost or wrongly identified; and in the interests of efficiency and economy, little time is wasted.

Pulse Modulator (communications/microelectronics)
Device used for the creating of modulation of a radio-frequency carrier signal. In pulse modulation, information is transmitted by generating a train of discrete pulses whose amplitude, duration, position, or mere presence is controlled in accordance with the signal.

Pulse Transformer (communications/microelectronics)
Iron-cored devices which are used in the transmission and shaping of low-power pulses whose widths range from a fraction of a microsecond to about 25 microseconds. Among the extensive applications of pulse transformers are the following: (1) coupling between the stages of pulse amplifiers; (2) inverting the polarity of a pulse; (3) changing the amplitude and impedance level of a pulse; (4) differentiating a pulse; (5) to effect "dc isolation" between source and load; (6) act as coupling element in certain pulse-generating circuits. As a passive element, it has none of the instability related to active elements.

Punch-in Recording (A/V, M/M)
A feature of MIDI sequencers and audio tape recorders enabling you to re-record only a particular segment of a performance, usually by live musicians.

Punch Register (computer/printing)
Use of punched holes and pins or studs to hold copy, film, masks, negatives, positives, and plates in precise register.

Purple Plague (computer/microelectronics)
Destructive, defect-causing formation of gold-aluminum chemical compounds often produced when gold and aluminum are bonded. Purple in color, brittle, subject to degenerative failure, and sometimes compounded by the inclusion of silicon.

Push/Pop (computer)
Term used for instructions that store and retrieve an item from a stack. Push enters the item on the stack, and pop retrieves an item, moving the other items up one level.

Push-Pull Amplifier (communications, microelectronics)
Two-transistor or two-tube amplifier circuit often used as the power-output stage of a multistage amplifier. A simplified circuit for a push-pull amplifier can be designed by having the input signals of equal magnitude but 180 degrees out of phase from each other. The collector current in the transistor with the positive signal is increasing while the transistor current in the other transistor is decreasing. This relation between the collector currents give rise to the name push-pull. Because of their phase relationship, the 2 currents flowing in the two halves of the primary winding produce an output similar to that of a single source connected to the transformer.

Pylon (A/V)
In Audio/Visual production, a pylon can be a triangular set piece, similar to a pillar.