R

Racking (A/V)
In Audio/Video production the rotating of the lens turret of the camera in order to change lenses. Also, the term can be used for moving the camera tube closer, to or farther away from the stationary lens by means of the focus knob on the camera.
Radar (communications)
Acronym for Radio Detection and Ranging, the original and still principal application of radar. The same is true to both the technique and the equipment used. The four principal parts are: transmitter, antenna, receiver, and display.

Radio (communications)
Transmission of electromagnetic energy (radiation) over the air or through a hollow tube called a waveguide. Although radio is often thought of as only AM or FM, all airborne transmission, including satellite and line-of-sight microwave, is radio.

Radio Frequency Amplifier (communications)
Tuned amplifier of high-frequency signals commonly used in radio communications. The frequency at which maximum gain occurs in a radio-frequency (rf) amplifier is made variable by changing either the capacitance or the inductance of the tuned circuit. A typical application is the amplification of the signal received from an antenna before it is mixed with a local oscillator signal in the first detector of a radio receiver. The amplifier that follows the first detector is a special type of rf amplifier known as an intermediate frequency amplifier.

Radio Receiver (communications)
That part of a radio communication system which extracts the desired information from the radio frequency (rf) energy collected by the antenna. All radio receivers must perform three basic functions: selectivity, amplification, and detection. Two general types of receivers are in common use: the tuned-radio-frequency (TRF) and the superheterodyne. Both of these can be used for amplitude-modulation (AM) signals. Frequency-modulation (FM) receivers are almost always of the superheterodyne type.

Radio Transmitter (communications)
Generator of high-frequency electric current whose characteristics of amplitude, frequency, or phase angle may be altered, or modulated, in accordance with the intelligence to be transmitted. A radio transmitter consists of components to accomplish the objectives of a particular design for a particular requirement. The power that a transmitter delivers in the antenna may vary from a fraction of a watt to 1,000,000 watts. Lower powers are used by portable or mobile services, while higher powers are required for broadcasting over large areas and in point-to-point communications. The different types of radio transmission are: amplitude modulation (AM); frequency modulation (FM), single sideband/independent sideband (SSB/ISB).

Radome (communications)
Strong, electrically transparent, thin shell to house a radar antenna, or a space-communications antenna or similar structure. It must be large enough not to interfere with the scanning motion of the antenna. In airborne radar the radome prevents the antenna from upsetting the aerodynamics of the aircraft, and protects the antenna against aerodynamic forces.

Ragged Right Alignment (computer)
Nonalignment of text at the right edge of a document.

RAID (computer)
Redundant Array of Inexpensive Disks: term used to describe the capability of installing multiple disk drives within a personal computer or workstation, to store very large amounts of information, while still keeping the information available to the end-user. For example, with the installation of eight, 200 gigabyte disk drives in a disk drive bay, the personal computer can now access 1,600 gigabytes (1.6 terabytes) of available memory storage capacity for an economical price. This system could be used as a file, network, database server.

RAM (computer)
Random Access Memory: computer memory structured so that the time required to access any data item stored in the memory is the same as for any other item.

RAMAC (history / computer)
Random Access Method of Accounting and Control: the IBM 305 RAMAC was among the first (late 1950s), if not the first, data processing systems to employ a magnetic disk file permitting direct random accessing of data records. It was essentially a unit record system enhanced by a stored program and direct access provided by its disk file.

RAM Disk (computer)
IC chip (integrated circuit) that can be installed to allow a personal computer to regard it as part of its memory, as a third or fourth disk drive: also called "phantom" disk. In software, a RAM disk is a block of memory set up to behave as though it were a hard disk drive. A RAM disk provides extremely fast performance, but, if power is lost, the contents of a software RAM disk are lost.

RAM Resident Program (computer)
Program that stays in the background of memory, ready to be activated when needed.

Random Access (computer)
Immediate access to a record in secondary storage, usually on disk.

Random Access Files (computer)
File category with records consisting solely of the user-defined (record or construct) data type. Each record has a fixed length, and individual records are located by calculating their position from the beginning of the file.

Randomize (A/V, computer)
In MIDI sequencing, the opposite of quantizing. Randomizing moves each note off the beat by a random time. Randomizing is used to reduce the mechanical ambience of music that is sequenced exactly on the beat.

Randomizing (computer)
Applying a formula to a key to yield a number that represents a disk address.

Random Number Generation (computer)
Computer procedure which scrambles the digits of an integer to produce a new integer. Scramble means to mix and combine by means of simple computer operations. The idea is to produce a sequence of integers which, in spite of being produced by a fixed procedure, will serve as random variables in computer simulations such as Monte Carlo, which is used to describe any simulation problem that uses random numbers.

Range (computer)
Term sometimes used to describe a group of one or more cells, arranged in a rectangle, that a spreadsheet program treats as a unit.

Range Extender (A/V)
In Audio/Visual production, an optical attachment to the zoom lens that will extend its narrow-angle focal length.

Raster Display (A/V, computer)
Display terminal that generates dots line by line on the screen (TV, Monitor, etc.).

Raster Font (computer/printer)
Font created as a graphic bitmap image. It is available only in a fixed size - not scalable. A raster font is used on screen, but also used by some dot-matrix printers and built into some laser printers.

Raster Graphics (A/V, computer)
Technique for representing a picture image as a matrix of dots. It is the digital counterpart of the analog method used in television. Unlike TV, however, which uses one standard (NTSC), there are may raster graphics standards.

Rasterization of Vectors (computer)
Conversion of graphic objects made up of vectors, or line segments, into dots for output to a raster graphics screen, dot matrix and/or laser printer. Unless vector graphics terminals and plotters are used, all object-oriented graphics must be converted to raster images for display on a terminal screen or for printing.

Raster-Scan Technology (A/V, computer)
Video display technology in which electronic beams cause the cathode-ray tube of the workstation video screen to emit light, to produce the screen image.

Ratings (A/V)
In Audio/Video production a term used to describe a rating system used to measure the percentage of television households with their television set(s) tuned to a particular station, in relation to the total number of television households.

Ray Tracing (computer/photonics)
Tracing of a ray of light as it traverses an optical system, so as to characterize the system. Also, in computer graphics creating reflections and shadows for image realization.

RBOC (communications)
Abbreviation for the original, seven Regional Bell Operating Companies.

RC Time Code (A/V, computer)
Rewritable Consumer time code. RC is a format developed by Sony Corporation and implemented in its VISCA-compatible products such as the Vdeck Hi8 VCR. RC is similar to SMPTE time code and uses Hours, Minutes, Seconds, Frames (HMSF) data to locate a specific frame for editing or synchronization purposes.

RCTL (computer/microelectronics)
Resistor-Capacitor-Transistor-Logic: Logic is performed by Resistors; Capacitors are used to enhance switching speed; Transistors are used to produce an inverted output.

RDBMS (computer)
Abbreviation for Relational Data Base Management Systems.

Reactance (computer/microelectronics)
Opposition that inductance and capacitance offer to alternating current through the effect of frequency. Reactance alters the magnitude of current and changes circuit phase angle.

Reaction Shot (A/V)
In audio/visual production, a shot showing the facial expression or other actions of a person or persons witnessing a news event (can also be called a cutaway).

Read (computer)
To acquire and/or interpret data from a memory device.

Read Only (computer)
Any storage media that permanently holds its content, such as ROM, PROM, CD ROM, compact disc, DVD, videodiscs or even a phonograph record.

Read Only File (computer)
File that the user can only open and read but cannot edit and save again.

Read Only Memory: ROM (computer)
ROM is based on a wide spectrum of storage technologies, the idea behind this storage, is that, for a number of applications, the storage contents are relatively fixed for a long period of time. For some applications, the contents of storage are not altered during the life of the machine.

Read/Write Head (computer)
Device that reads (senses) and writes (records) data on a magnetic disk or tape. For writing, the surface of the disk or tape is moved past the read/write head. By discharging electrical impulses at the appropriate times, bits are recorded as tiny, magnetized spots of positive or negative polarity. For reading, the surface is moved past the read/write head, and the bits that are present induce an electrical current across the gap.

Ready Mode (computer)
Spreadsheet mode indicating the program is ready for whatever action the user specifies.

Realizing The Palette (computer/printer)
Process of assigning a set of colors in the application's logical palette to the system palette, so they appear on the display.

Real Storage (computer)
Term sometimes used to describe that part of memory that temporarily holds part of a program pulled from a virtual storage memory partition, or allocation.

Realtime (communications, computer)
Immediate response - electronic operation that is performed in the same timeframe as its real-world counterpart. For example, it takes a fast computer to simulate complex, solid models moving on screen at the same rate they move in the real world. Realtime video transmission produces a live broadcast. Realtime imaging, in computer graphics, means a graphics image can be animated on screen in the same time frame as in real life. MIDI System Real-Time messages synchronize instruments based on the MIDI clock.

Realtime Processing (computer)
Processing in which the results are available in time to affect the activity at hand.

Realtime Systems (communications, computer)
Computer systems in which the computer is required to perform its tasks within the time constraints of some process or simultaneously with the system it is assisting. Usually the computer must operate faster than the system assisted in order to be ready to intervene appropriately. Real-time computer systems and applications span a number of different types: real-time control; real-time assistance; real-time robotics.

Rear Screen (A/V)
In Audio/Visual production a translucent screen onto which images are projected from the rear and viewed or photographed from the front.

Reciprocity Principle (computer, microelectronics)
Applies to a physical system whose input and output can be interchanged without altering the system response to a given excitation. Optical, acoustical, electrical, and mechanical devices operatiing equally well in either direction are reciprocal systems, whereas unidirectional devices violate reciprocity. The theory of reciprocity facilitates the evaluation of the performance of a physical system. If a system must operate equally well in two directions, there is no need to consider any non-reciprocal components. Examples of reciprocal systems include: electrical networks composed of resistances, inductances, capacitances, and ideal transformers; systems of antennas; mechanical gear systems; and light sources, lenses, and reflectors.

Record (A/V, computer)
Synonym for a user-defined data type. Also it is used in database applications to define a single element of a relational database file containing each of the fields defined for the file. In A/V terminology to begin to create audio/video information from a source device (camera, TV, VCR, computer, etc.), to a destination device (TV, VCR, computer, etc.).

Record Review (A/V)
In audio/visual production, a feature on some camcorders, while in record/pause mode: the user can use the record review buttons to check the last few second of video tape just recorded. This lets the user make sure that their shots came out the way they wanted.

Record VTR (A/V)
In Audio/Visual production, the videotape recorder that receives and assembles the various program segments as supplied by the source video tape recorder(s).

Rectifier (communications, computer)
Nonlinear circuit component that allows more current to flow in one direction than in the other. An ideal rectifier is one that allows current to flow in one (forward) direction unimpeded but allows no current to flow in the other (reverse) direction. Thus, ideal rectification might be thought of as a switching action, with the switch closed for current in one direction and open for current in the other direction. Rectifiers are used primarily for the conversion of alternating current (ac) to direct current (dc).

RECOVER (computer/DOS)
DOS Command that recovers files from a bad or defective disk. This command reads a disk and recovers sectors from the available files that it can find. This command is used when the user has a damaged disk where there are files that need to be recovered. It may or may not be able to recover these files.

Recursion (computer)
Condition in which a procedure or function calls itself during its execution.

Red Book Audio (A/V, computer, M/M)
Audio storage and CD-ROM output specification in Philips N.V's red-bound book and used in Windows Multimedia extensions as the standard for CD-ROM audio processing.

Reduced Instruction Set Computer: RISC (computer)
Microprocessor that is programmed with RISC set of instructions.

Redundant Array of Inexpensive Disks: RAID (computer)
Class of storage that uses several connected disks that act as a unit. Using multiple disks allows users to partition date, improve security, access time, and data transfer speed.

Reel-To-Reel (A/V)
In audio/visual production, a tape recorder that transports the tape past the heads from one reel (the supply reel), to the other reel (the takeup reel); used in contrast to video cassettes or cartridge type recorders.

Reference White Level (A/V)
In audio/visual production, the level corresponding to the maximum white portion of a video picture that can be reproduced without a total loss of texture.

Reformat (computer)
To format a diskette, again, to insure formatting reliability. Also, to readjust information, text, data, that have been altered during processing.

Reflected Light (A/V)
Light that is bounced off the illuminated object. Reflected light reading is done with a light meter (most are calibrated for reflected light) held close to the illuminated object. Reflected light is measured in footlamberts; while incident light (light falling on the object) is measured in footcandles; the amount of light energy actually leaving the surface of the lamp is called output, or "direct" light, and is measured in watts.

Reflection (A/V, communications/photonics)
Change of direction of the propagation of a light beam after striking a mirror.

Reflective Art (A/V, computer/printing)
Artwork, such as photographs or paintings, viewed by reflected light (not transparency).

Refraction (A/V, communications/photonics)
Bending of rays of light, heat, or sound as they pass through different materials. The change of direction when a light wave passes from on medium to another (say, from water to air).

Refresh (A/V, computer)
Continuous charge to a device that cannot hold its content. Screens (CRTs) must be constantly refreshed because color phosphors hold their glow for only a few milliseconds. Dynamic memory chips (DRAMs) require constant refreshing to maintain their charged bit patterns. Refresh rate in computer graphics, is the time it takes to re-draw or re-display an image on the screen. Also, to update displayed information with current data.

Regeneration (communications, computer)
Process of feeding back a portion of the output signal of an amplifier to its input in such a way that the input signal is reinforced. The result is greatly increased amplification. The feedback must be positive: the two signals must be in phase, and it must be limited in magnitude to prevent the circuit from going into oscillation. In storage devices for computers, regeneration involves the restoration of deteriorating electrostatic, magnetic, or other conditions to their original state. This is essential in charge-storage, cathode-ray tubes (screens) to overcome natural decay effects.

Register (computer/microelectronics)
Memory location used for specific logical or control functions. It is a specialized storage element; its purpose is to store a string of bits representing related information. All registers in a computer are uniquely identified by names or address. Registers are provided with the means to load new words or individual bits and to sense the register's contents. The number of bits that can be stored in a register indicate the register's length (8-bit, 16-bit, 32-bit registers, etc.) Registers of different lengths can be on the same system; the most common length is the word length of the computer.

Registration (A/V, computer/microelectronics)
In microelectronics fabrication, the degree of proper alignment of a circuit pattern on a substrate. In audio/visual production, adjusting the scanning of the three color generators (tubes, charged coupled devices) so that screen images overlap (register) perfectly; it is the coincident or accurate alignment of RGB images to form a faithful reproduction of the original scene's colors and lines.

Registry (computer/DOS)
Database repository for information about a computer's configuration.

Regression Analysis (computer)
Using computers to build models explaining a dependent variable in terms of a set of independent variables: the hope is that extrapolation into new population sets other than those observed can be performed by choosing values of the independent variables for new cases and thereby predicting the most likely value of the dependent variable. For example, one might wish to predict age at death (the dependent variable) on the basis of life habits, genetic characteristics, living conditions, and physiology (the independent variables).

Regulation (computer/microelectronics)
Process of maintaining a quantity or condition essentially constant despite variations in such factors as line voltage and load. In an industrial process-control system, the speed, temperature, voltage, or position of a critical element can be kept constant by measuring the condition being regulated, and feeding back into the system a signal representing the difference between the actual and the desired quantities.

Regular Expression (computer)
Formal description for a language acceptable by a finite automaton or for the behavior of a sequential switching circuit is known as a regular expression. It tells how a language is built up from atomic languages, using regular operations.

Relational Database (computer)
Organizing files in a database that prohibits linking files together. Relationships between files are created by comparing data (numbers, names). Relational systems can take any two or more files and generate a new file from the records that meet the matching criteria.

Relational Operators (computer)
Consisting of operators such as >, <, <>, and =. that compare values of two operands and return true or false depending on values compared (can be called comparative operators).

Relaxation Oscillator (communications, computer, microelectronics)
Electronic circuit which has two stable states, resulting in two distinct output levels, and which switches between the two states at a rate determined by the rate of rise or decay of voltage across the storage element. The output waveform is usually nonsinusoidal and may approximate a square wave, a sawtooth wave, or a series of short repeating pulses. One of the most widely used forms of relaxation oscillator is the astable multivibrator, which generates a rectangular or square wave. In this circuit, two devices are connected so that they are alternatively ON or OFF. Connected together by a positive feedback path, they are driven rapidly from one state to the other. There is also a class of circuits in which a single device has two stable conditions, either ON-OFF or ON, with two distinct states or levels. The blocking oscillator is representative of such a circuit, which also include a positive feedback path. Negative-resistance devices such as tunnel diodes can be used as a relaxation oscillator.

Relay Lens (A/V)
In audio/visual production, part of the internal optical system of a camera that helps to transport (relay) the separated color light into the pickup tube or photoreceptor.

Reliability Engineering (A/V, communications, computer)
Domain of reliability engineering involving considerations of all aspects of design, development, and implementation so as to minimize system breakdowns. Neglect of reliability considerations can be very costly, from the loss of consumer acceptance of the product to the possibility of endangering human life. The success of complex missions depends heavily on reliability engineering since failure of a single component could result in the total loss of the system.

Reluctance (computer, microelectronics)
Property of a magnetic circuit analogous to resistance in an electric circuit.

REM (computer/DOS)
DOS Command that adds a line that DOS will not process to a batch or CONFIG.SYS file. After the REM command, the user can enter any commentary text.

Remote (A/V)
In audio/visual production, a television production done outside of the studio.

Remote Administration (communications, computer/Windows)
Administration of one computer by an administrator located at another computer and connected to the first computer across the network.

Remote Control Unit (A/V)
In audio/visual production, a term sometimes used to describe the part of the camera chain with which the video operator achieves optimal pictures during remote production.

Remote Job Entry: RJE (computer)
Term refers to the submission of jobs to a central computer from a remote location. the Job entry becomes remote when the length limits of the connection between input/output devices are exceeded, in which case the communications carrier link must be used to bridge the gap. Also, traditionally, RJE jobs are batch jobs, in that they do not require transaction processing (response within seconds or minutes of a system request), nor do they require realtime processing (response that is perceived as instantaneous).

Remote Procedure Call: RPC (communications, computer/Windows)
Message-passing facility that allows a distributed application to call services available on various computers in a network. It is used during remote administration of computers.

Remote Procedure Call Service (computer/Windows)
Remote Procedure Call subsystem for Microsoft Windows Networking. The subsystem includes the endpoint mapper and other miscellaneous RPC services.

Remote Procedure Call Locator Service (computer/Windows)
Allows distributed applications to use RPC Name service. RPC Locator service manages the RPC Name service database. The server side of a distributed application registers its availability with the RPC Locator service. The client side of a distributed application queries the RPC Locator service to find available compatible server applications.

Remote Survey (A/V)
In audio/visual production, an inspection of the remote location by key production people so that they may better plan for the setup and use of production equipment.

Remote Truck (A/V)
In audio/visual production, the vehicle that carries production equipment such as camera control units (CCUs), switchers, monitors, audio control consoles, intercom systems, cabling, video recorders, and which can serve as a production control center.

Removable Disk (computer)
Disk that can be inserted and removed at the user's discretion (form example mini diskettes).

Repeater/Regenerator (communications)
Device that amplifies or regenerates a signal in order to extend the distance of the transmission. It is available for both analog and digital signals. Repeaters generally now imply analog amplification. Regenerators in digital communications, reference and check the bit stream, bytes, packets for correctness and then re-generate the patterns, thus preventing any "De-Generation" or distortion of the original bit pattern. This enables voice and data signals that are packetized to remain as good at the last re-generation point as at the first, as opposed to repeaters that can induce their own "noise", and can only amplify what they receive whether it is "clean" or "noisy".

REPLACE (computer/DOS)
DOS Command that replaces all files on one disk with those from another, or adds files from one disk to another. This command is used to update the contents of directories.

Report Generator (computer)
Program or routine that provides the user with a set of functions which are oriented towards the generation of a report, either standardized or specialized (unique), thereby greatly reducing the programming problems associated with generating specific reports on information databases (also provides specialized formatting features).

Reserved Word (computer)
Synonym for keyword. A reserved word sometimes indicates a subset of keywords that do not include embedded keywords.

Reset (computer/microelectronics)
In microelectronics a term describing a logic function "To clear"; similar to "Set", except that Reset is the input through which Q output can be made to go to the condition "0".

Residual Error Rate (communications, computer)
Error rate remaining after attempts at correction are made.

Resist (computer/microelectronics)
In microelectronics fabrication, material such as ink, paint, or metallic plating, used to protect the portions of the printed conductive pattern from the action of the etchant, solder, or plating.

Resistance Measurement (computer/microelectronics)
Quantitative determination of that property of an electrically conductive material, component, or circuit called electrical resistance. The unit of measurement is called the ohm. Resistance may be measured by using either direct or alternating current (dc or ac). If dc is used, the true resistance of the conductor is measured. When the measurement is made with ac, the result is usually called the effective resistance.

Resistor (compute/microelectronics)
Component of an electric circuit that produces heat while offering opposition, or resistance, to the flow of electric current. All conductors exhibit resistance in varying degrees; however, the term resistor is generally used only to describe a device specifically used to introduce resistance into an electric circuit. the unit of resistance measurement is the ohm. Resistors are described by starting their total resistance in ohms along with their safe power-dissipating ability in watts. Resistors can be classified according to the general field of engineering in which they are used, such as: power resistors; instrument resistors; resistors for electronic circuits; composition resistors, film-type resistors; wire-wound resistors; potentiometer/variable resistors.

Resolution (A/V, computer)
Degree of sharpness of a displayed or printed character or image. On screen, resolution may be expressed as the number of dots per line by the number of lines. A 680x400 resolution means 680 dots across each of 400 lines. The same resolution looks sharper on a small screen than it does on a large screen. For printers, resolution is expressed as the number of dots per linear inch. A desktop laser printer prints at 300 dpi (300 across, 300 down) or 90,000 dots per square inch. A 600 dpi prints 360,000 dots per square inch. It can also be stated as the measure of the division of the duration of an event into smaller parts. The resolution of the timing of MIDI messages is determined by the MIDI clock rate. The resolution of a digital sample is measured in bits. The higher the number of bits in the sample, the greater the possible fidelity of its reproduction (and the greater the amount of storage space is required).

Resonance (A/V, communications/photonics)
Condition in which the frequency of an input wave is the same as an inherent frequency of a physical device, and the wave can cause large oscillations.

RESTORE (computer/DOS)
DOS Command restoring files from a backup disk made with BACKUP command. The switches and parameters let a user select the backed up files that are restored.

Restore (computer/Windows)
In Windows, to return an application window or document window to the size and position it had before it was maximized or minimized.

Restore Button (computer/Windows)
In Windows, a small box containing a Down arrow and an Up arrow at the right of the title bar. the Restore button appears after the user has enlarged a window to its full size. Mouse users can click the Restore button to return the window to its previous size. Other methods include using the Restore command on the Control Menu.

Replication (computer/Windows)
Copying of a master set of directories from a server (called an export server) to specified servers or workstations (called import computers) in the same or other domains. Replication simplifies the task of maintaining identical sets of directories and files on multiple computers, because only a single master copy of the data must be maintained. Files are replicated when they are added to an exported directory and every time a change is saved to the file (Directory Replicator Service).

Resolution (A/V)
In audio/visual terms, a characteristic of a camera that determines the sharpness of the picture received. The lower a camera's resolution, the less fine the picture detail. Resolution can be affected by a number of elements: pickup tube or photoreceptor, lens, internal optical systems, and the monitor or television the image is viewed on.

Resonance (communications, computer/microelectronics)
Condition in a circuit characterized by relatively unimpeded oscillation of energy from a potential to a kinetic form. In an electrical network there is oscillation between the potential energy of charge on capacitance and the kinetic energy of current in inductance. This is analogous to the mechanical resonance seen in a pendulum. Resonance is of great importance in communications, permitting certain frequencies to be passed and others to be rejected. Thus a pair of telephone wires can carry many messages at the same time, each modulating a different carrier frequency, and each being separated from the others at the receiving end of the line by an appropriate arrangement of resonant filters.

Resource (computer)
Any part of a computer system or a network, such as a disk drive, printer, or memory, that can be allocated to a program or a process while it is running.

Resource Allocation (computer)
Process of assigning resources to certain programs.

Response (A/V, communications, microelectronics)
Quantitative expression of the manner in which a microphone, amplifier, loudspeaker, or other component or system performs its intended function. A linear response means that the output signal is exactly proportional to the input signal for the entire range of frequencies over which the device is intended to operate.

Response Time (computer)
Time between the input of a request to the computer, and the computer's response.

RETMA (A/V)
Radio Electronics and Television Manufacturers Association - originally the RMA U.S. Cabling standards such as RS-170, RS-170-A, and RS-232-C and the color codes for the values of resistors and capacitors were originally developed by RETMA. Most of the standardization activities of RETMA now have been taken over by the IEC.

Retouching (A/V, computer/printing)
Correcting imperfections in a photograph before it is reproduced.

Retrieval (computer)
Recovery of information stored in a computer system.

Reverberation (A/V, music, M/M)
Acoustic echoes changing the nature of sound in different environments. Higher levels of reverberation occur from live acoustic environments characterized by hard surfaces such as plastered walls. Longer reverberation delays occur with larger enclosures such as concert halls. Reverberation effects can be duplicated by digital signal processing.

Reverse Engineering (computer)
Term describing the competitive facility to take an original product, break it down into generic, component parts, rebuild it without appearance of infringement on any patents or copyrights.

Reverse Shot (A/V)
In audio/visual production, a shot taken from exactly opposite the previous one; the reverse angle to show a scene "from the other side".

Reverse Type (computer/printing)
White type against a black ground (as opposed to normal black on white).

Reverse Video (A/V, computer)
Display mode sometimes used for highlighting characters on the screen. For example, if the normal display mode is white on blue, the reverse video would be blue on white.

RF (communications)
Radio Frequency - the range of electromagnetic frequencies above the audio range and below visible light. All broadcast transmission, from AM radio to satellites, falls into this range, which is between, 30 kHz and 300 Ghz.

RFP (A/V, communications, computer)
Abbreviation for Request For Proposals, a term used to describe a comprehensive request for equipment, services, and/or maintenance on complete systems, or hardware and software items. This is usually prepared by the customer and sent out to interested suppliers of equipment and services, after which an evaluation of the responses is made, before the actual award of the RFP and purchasing is made.

RF Modulation (communications)
Transmission of a signal through a carrier frequency. Some home computers and all VCRs provide RF modulation of a TV channel, such as Channel 3 or 4, to hook up directly to a TV.

RGB (A/V, computer)
Red, Green, Blue - the method of recording and generating colors in a video system. On a television or color monitor, colors are displayed as varying intensities of red, green and blue dots. When red, green and blue are all turned on high, white is produced. As the intensities are equally lowered, shades of gray are produced. When all dots are turned off, the base color of the screen appears. Color printing uses the CMY or cyan, magenta, yellow system for mixing colors. In RGB, colors add to create white. In CMY, colors are subtracted to create white.

RGB Monitor (A/V, computer)
A video display screen that requires separate red, green, and blue signals from the computer. It generates a higher-quality image than composite signals, in which all three colors are transmitted together (standard TV). RGB monitors come in both varieties.

Ribbon Cable (computer)
Thin, flat, multiconductor cable widely used in electronic systems, for example, to interconnect peripheral devices to the computer internally and externally (usually short). The multiconductor cable comes with each, individual conductor moulded together. One side of the ribbon cable is marked with a printed line, usually blue or red. This line identifies the conductor corresponding to pin 1 of the attached connectors.

Ribbon Microphone (A/V)
Term used for a microphone with a ribbon device that vibrates according to acoustic pressure (sound) within a magnetic field (also, sometimes called a velocity microphone).

RIFF (computer/Windows)
Windows Resource Interchange File Format - it is used in conjunction with Multimedia Extensions. Depending upon their definition, these files may contain MIDI sequence, sample dump, or system exclusive data; waveform audio files; or data to create graphic images. RIFF is the preferred file format for Windows multimedia files, however, some third-party applications currently create RIFF files, except in WAVE format (WAV files).

RIFF Files (computer/Windows)
Files that are format compatible with the joint IBM-Microsoft specification for RIFF files. Examples are WAVE (WAV) files for WaveAudio sound, RMID (RMI) files for MIDI applications, and RMMP (MMM) files for the Multimedia Movie Player.

Right (computer/Windows)
Authorizes a user to perform certain actions on the system. Rights apply to the system as a whole, and are different from permissions, which apply to specific objects.

Ringing (A/V)
In audio/visual production, term used to describe the secondary edge or ghost edge, usually on the right side of objects in the picture, caused by excessive video enhancement.

Ring Network (communications, computer)
Term sometimes used to describe a "circle" of connections between computers at local sites. A ring network does not usually contain a central host computer (see token ring). A Ring Network Implementation can have a Local Area network that connects terminals and computers in a physical or logical circle. It can be a large circle running around the perimeter of the Local Area Network Workstations, or it can be a tiny circle that is implemented on an integrated circuit board, with longer workstation connections to the LAN controller IC boards (physical or logical ring implementation remains the same).

RIP: Raster Image Processor (computer/printing)
Component of an output device that rasterizes the image.

Ripple (computer/microelectronics)
Transmission of data serially (one bit at a time). It is a serial reaction analogous to a row of falling domino blocks (one cascading into another, appearing like a ripple).

Ripple ADDER (computer/microelectronics)
Binary adding system similar to the system used for adding decimal numbers: adding the units column first, get the carry, add it to the "10s" column, get the carry, add it to the "100s" column, and so on. In a binary system, the same process is used except that there are only two numbers (0 and 1) not 10 as in a decimal system. With the Ripple ADDER, it is necessary to wait for the signal to propagate through all the adder columns even though all columns may present at once (as in parallel circuit). The Carry is "rippled".

Ripple Counter (computer/microelectronics)
Binary counting system, in which flip-flops are connected in series. When the first flip-flop changes, it effects the second, which effects the third, and so (like falling dominoes). If there are ten flip-flops in a row, the signal must go sequentially from, first to tenth.

Ripple Voltage (computer/microelectronics)
Total voltage across the load resistor of a rectifier minus the average voltage across the same resistor. The ripple can be expressed as a Fourier series. The fundamental frequency of the ripple voltage of single-phase, half-wave circuits is identical to the alternating-current input.

Riser (A/V)
Term used in audio/visual production to describe a small platform, or the vertical frame that supports the horizontal top of the platform.

Riser Room (communications)
Term used in communications cabling within a building to describe the communications rooms or closets that are stacked, one on top of the other, in a vertical row, that provide access to large cabling groups, from floor to floor in a building.

Risers (communications, computer/microelectronics)
In communications terms, the cabling bundles that "rise" at specific locations, vertically, within communications rooms or "riser rooms" in a building.

In microelectronic fabrication, risers describe, in a multilayer substrate, the conductive paths that vertically connect to various levels in the stacked wafer grid (multilayer substrate).

Rise Time (computer/microelectronics)
Measure of the time required for the output voltage of a state to go from a low voltage level ("0") to a high voltage level ("1") once a level of change has been put in motion.

Ritardando (A/V, music, M/M)
A musical term indicating the playing tempo is gradually slowing.

RISC (computer)
Reduced Instruction Set Computer - computer architecture that performs a limited number of instructions. The concept is that most programs generally use only a few instructions, and if those instructions are made to execute faster, performance is increased. RISC eliminates a layer of overhead called microcode, which is used to make it easier to add new and complex instructions to a computer. RISC computers have a small number of instructions built into the lowest level circuits. RISC computers are somewhat less flexible than CISC (complex instruction set) computers. RISC computers are about 15% to 35% faster than their CISC counterparts. There is controversy over RISC. Its proponents claim its speed and lower cost is an extreme advantage. Its opponents claim its improvements are not worth proliferating the industry with new machine languages and that far greater performance improvements will be coming anyway. In addition, because many instructions are eliminated, the software (assemblers, compilers) must generate more code to do what used to be done by hardware. With a 6 or 10 gigabit per second central processing chip, at this speed - using CISC or RISC becomes a moot point.

RMDIR or RD (computer/DOS)
DOS Command that removes the specified directory.

Robot (computer)
Computer-controlled devices that can physically manipulate its surroundings.

Robotics (computer)
Study of the design, application, and control and sensory systems of robots. The emergence of robotics as a separate discipline has been given impetus by the developing complexity of robot systems, which has emphasized the interdependence of the design of the mechanical, electronic, and computational aspects of robots.

Rock Ridge Format (A/V, computer)
Standard for CD-WO providing directory structures updated as additional files are added. Rock Ridge directory format is used for multiple session Photo CD-ROMs.

Roll (A/V)
Term used in audio/visual production to describe graphics, usually credits, that move slowly up the screen. Roll can also mean to roll tape or film.

ROM (computer)
Read Only Memory - memory chip that permanently stores instructions and data. Its contents are placed in ROM when made and can’t be altered. It is used to hold codes and programs that are permanent. ROMs are used in cartridges for calculators, game computers, and laser printers. They are used in some (very few) notebook computers to hold operating systems, however, if there is an update to any of the program, the ROM chip has to be replaced. ROM chips are also used to store prerecorded, digitized sound samples in sample-playback musical synthesizers.

ROM BIOS (computer)
ROM Basic Input/Output System - a set of routines stored in a ROM chip in a PC. The BIOS contains the drivers, or access methods, that activate devices directly.

ROM Burner (computer/microelectronics)
Term sometimes used for a specialized device used to program read-only memory.

Rosettes (computer/printing)
Patterns formed when halftone color images are printed in registration at the correct screen angles (used in photo-art, photo-typesetting, offset printing, color printing).

Root Directory (computer)
In hierarchical file systems, the starting point in the hierarchy. Access to directories in the hierarchy (i.e. DOS) requires naming the directories in the path from the current directory to the destination directory, but going back up or sideways requires naming the entire path starting from the root directory.

Rotary Motion (computer/microelectronics)
Also called "theta" motion: in fabrication, an angular (rotary) adjustment of image to substrate, it allows for registration in angularity in addition to "x" and "y" screen printing (theta motion).

Rotational Delay (computer)
Time it takes for a record on a track to revolve under the disk drive read/write head.

Rough Cut (A/V)
In audio/visual terms, the first arrangement of shots and sequences in the approximate sequence and length for a particular shot, scene, or program element.

Roundoff Error (computer)
Errors that can occur when data for a calculation must be rounded to n-bits when read into and stored in the computer (can be significant when dealing with millions of numbers), or when the final total number is based on approximations at the input stage of the program calculation.

Round Robin Scheduling (computer)
Term sometimes used to describe a system to share computer resources (taking turns).

Router (communications)
Device that selects the appropriate travel path and routes a message accordingly. Routers are used in networks where there are many pathways in the network. The router examines the destination address of the message and determines the most effective route.

RPC: Remote Procedure Call (computer/Windows)
Message passing facility that allows a distributed application to call services available on various computers in a network: used during remote administration of computers.

RPC Locator Service (computer/Windows)
Service that allows distributed applications to use the RPC Name service. The RPC Locator service manages the RPC Name service database. The service side of a distributed application registers its availability with the RPC Locator service. The client side of a distributed application queries the RPC Locator service to find available compatible server applications.

RPC Service (computer/Windows)
Remote Procedure Call services is the RPC subsystem for Microsoft Windows Networking. The RPC subsystem includes the endpoint mapper and other miscellaneous RPC services.

RPG: Report Program Generator (computer)
Problem-oriented language designed to help produce customized, personalized reports.

RPM (computer)
Revolutions Per Minute - used to measure the speed of a disk drive. Floppy disks rotate at 300 rpm, while hard disks rotate at 2,400, 3,600, 4,800, 5,400, 6000, 7,200 rpm.

RS-232-C (computer)
Connector: 25-wire electrical interface between a computer and a peripheral device, such as a modem, drawing tablet or printer. It is an EIA standard for serial transmission that uses a 25-pin DB-25 or 9-pin DB-9 connector. Its normal cable limitation is 50 feet but with higher quality cables it can be extended to 100 or more. The same DB-25 connector used in RS-232 cables is also used as a connector for parallel printer cables (only used locally, at the machine - not for LANs or long signalling cabling). It was originally used to connect modems, but is now used to describe the PC's serial I/O port(s). COM1 through COM4, and any device or cable connecting to them. It is used to control many types of devices (Sony's VISCA-compatible camcorders and VCRs). The C suffix is often dropped when referring to RS-232-C.

RS-422, 423, 449 (computer)
Connectors: EIA standards for serial transmission that extend distance and speeds beyond the RS-232 standard. Both interfaces typically use a DB-37 connector, but may be implemented with a variety of other connectors. RS-422 is a balanced system requiring more wire pairs than RS-423. RS-449 specifies the pin definitions for RS-422 and 423. RS-422 and 423 are subsets of RS-449, each specifying the electrical and timing characteristics of the lines (only used locally at the machine - not for LANS or long signalling cabling). RS-422 is an updated version of the RS-232-C standard. The RS-422 was first designed for use with higher-speed modems. Some VCRs with remote control, such as the Panasonic AU-series use RS-422 connections for their control signals.

RTL (computer/microelectronics)
Resistor-Transistor-Logic: Logic is performed by resistors; Transistors are used to produce an inverted output (see RCTL also).

Run (computer)
In computer terms, Run describes the execution of a program (i.e. "to run the program").

Rundown Sheet (A/V)
Term sometimes used in audio/visual production to describe a fact sheet (information).

Running Time (A/V)
Term used in audio/visual production to describe the duration of a production, or a production element (also can be called program length).

Runout Signal (A/V)
Term used in audio/visual production to describe the recording of a few seconds of black (no information) at the end of a videotape recording to keep the screen in place for a video roll-over, change-over, or some other edited addition.

Run-Through (A/V)
Term used in audio/visual production to describe a rehearsal ("from the top", etc.).