Q

QAM (communications)
Quadrature Amplitude Modulation - a modulation technique that generates four bits out of one signal shift (baud). For example a 600 baud line (600 shifts in the signal per second) can effectively transmit 2,400 bits per second using this method. Both phase and amplitude are shaped with each signal shift resulting in four possible patterns.

QBASIC (computer/DOS)
DOS Command that loads the BASIC interpreter that lets a user program in BASIC and run the programs. BASIC is a programming language that can be used to develop end-user programs. The editor for BASIC programs is similar to the EDIT system editor.

QMF: Query Management Facility (computer)
IBM mainframe fourth generation language implemented on the DB2 database platform.

Q Output (computer/microelectronics)
Reference Output of a flip-flop. When this output is "1", the flip-flop is said to be in the "1" state; when it is "0" the output is said to be in the "0" state.

Quadruplex (A/V)
In Audio/Visual production, a scanning system of videotape recorders that uses four rotating heads for recording and playing back of video information. All quadruplex, or quad recorders, use 2-inch wide format videotape.

Quad-Split (A/V)
In Audio/Visual production, a switcher mechanism that makes it possible to divide the screen into four variable-sized quadrants and fill each one with a different image.

Quantize (A/V, computer)
Process in a MIDI sequencer application causing notes to be precisely aligned at fractional intervals of a measure (exact quarter, eight, sixteenth, or thirty-second notes). Excessive quantizing of music leads to a mechanical sound, causing MIDI choke, a condition caused by a controller trying to send an excessive number of MIDI messages at a single instance.

Quantum Theory (communications, microelectronics)
Fundamental hypothesis that matter may be endowed with a dualistic nature, that particles such as electrons may also have the characteristics of waves. This hypothesis found expression in the definite form now known as the Schrodinger wave equation, whereby an electron is represented by a solution to these equations. The nature of such solutions implies an ability to penetrate classically forbidden regions of negative kinetic energy and a probability of tunnelling from one classically allowed region to another. The concept of tunnelling arises from this quantum-mechanical result. The subsequent experimental manifestation of this concept, such as high-field electron emission from cold metals, in the 1920s can be regarded as one of the early triumphs of the quantum theory.

Quarter-Track (A/V)
In Audio/Visual production, an audiotape recorder, or recording, that uses one-fourth of the width of the tape for recording an audio signal: generally used by stereo recorders. The first and third tracks are taken up by the first pass of the tape through the recording heads; the second and fourth tracks by the second pass, when the tape as been reversed (that is, the full take-up reel becomes the supply reel for the second recording).

Quartz Crystal (computer/communications)
Thin slice of quartz that has been cut and ground to a prescribed thickness, which vibrates at a specific and steady frequency when stimulated by electricity. This small crystal, approximately 1/20th by 1/5th inch, creates the computer clock pulse timing mechanism.

Quartz Light (A/V)
In Audio/Visual production, a high-intensity light whose lamp consists of a quartz or silica housing (instead of the customary glass) and a tungsten-halogen filament: it produces a very bright light of stable color temperature (about 3,200 degrees Kelvin).

Query (computer)
Term used to describe an inquiry and manipulation of a database.

Query Language (computer)
Term used to describe a specialized language for database queries (i.e. SQL).

Queuing Network Models (computer)
Modelling for a wide variety of important aspects of multi-programmed computer systems including: multiple-task jobs, different job classes, queuing for resources, concurrency among devices, bottlenecks, and saturation.

Queuing Theory (computer)
Whenever demands occur in production, transportation, communications, computer usage, or other types of service systems, waiting lines are built up, resulting in the blocking of resources and in losses of time, money, patience, and good will. Efforts to control congestion can be of vital importance, and have led to rapid growth "queuing theory", which is the study of waiting-line processes through the use of mathematical/computational and simulation models.

QuickDraw (computer)
Apple Computer graphics - describes graphical objects created on Macintosh computers.

Quick Format (computer/DOS/Windows)
Deletes file allocation table and root directory of a disk but does not scan for bad areas.

Quick Study (A/V)
In audio/visual production, a performer who memorizes lines quickly and effortlessly.

QuickTime (computer)
Apple Computer - method employed for digital imaging and audio multimedia. The Microsoft AVI Development Kit includes a QuickTime to AVI conversion application.

Qwerty Keyboard (computer/typewriter)
Standard English typewriter keyboard. Q W E R T and Y are the first letters starting at the top left row. It was originally designed to slow down the typist to prevent the keys from jamming.