J

J – Jack (A/V, communications, computer) to Justification (computer)



Jack (A/V, communications, computer)
Sometimes called a "jack" a receptacle into which a plug is inserted.

Jaggies (computer)
Stair-stepped appearance of diagonal lines on a low-resolution graphics screen.

Jam (communications)
Signal sent through a network indicating that there has been a data collision.

Jitter (A/V, communications, computer)
Flickering transmission signal or display image: also picture instability in VTR playback.

Job (computer)
Task or group of tasks performed by a computer: the number of tasks (or steps) per job is usually a preference of the programmer, but is also subject to the conventions of the operating system.

Jogging (A/V, production)
Frame-by-Frame advancement of videotape with a VTR or VCR (also called jog-shuttle).

Josephson Effect (computer/microelectronics)
Term used in microelectronic fabrication for the tunnelling of electron pairs through a thin insulating barrier between two superconducting materials.

Josephson Junction Devices (computer/microelectronics)
This tunnel junction, whose effect was first predicted by Brian Josephson in 1962, typically consists of a thin insulating layer (about 15 atomic layers thick) sandwiched between two superconducting (zero resistance at -270 celsius) films. When placed in a suitable cryogenic environment (such as liquid helium) these junctions form the basis of ultra-fast switching circuits with transition times of only tens of picoseconds, and power dissipations of a few microwatts. Such high-speed and low-power dissipation make the technology of Josephson junction devices useful in ultra-high performance computers.

Joule's Law (computer/microelectronics)
Quantitative relationship between the quantity of heat produced in a conductor and an electric current flowing through it. The law (J.P. Joule) states that when a current of voltaic electricity is propagated along a metallic conductor, the heat evolved in a given time is proportional to the resistance of the conductor, multiplied by the square of the electric intensity. Today, the law would be stated as H=RI(squared), where H is the rate of evolution of heat in watts, the unit of heat being the joule; R is the resistance in ohms; and the I is current in amperes (squared).

Joystick (computer)
Manual input device for graphics display consoles that allows the user to specify simultaneously the two or three coordinates of a point in two or three dimensional space (it is most popularly employed in the home, as a device for playing video games).


Joystick Positioned (A/V)
Audio/Visual term used to describe the video switcher control that allows the user to move wipe patterns about the screen.

JPEG (A/V, computer)
Joint Photographic Experts Group - JPEG has established an industry standard for photographic image compression.

JPG (A/V, computer)
File extension for graphic image files stored using JPEG compression.

Jump (computer)
In programming, execution of code in a sequence different from how it appears in the source code. In most cases, a jump will skip over lines of code as the result of the evaluation of a conditional expression. In some cases, a jump will cause another subroutine to be executed.

Jump Cut (A/V)
Cutting between shots that are identical in subject yet slightly different in screen location. Through the cut, the subject seems to jump from one screen location to another for no apparent reason. Any abrupt transition between shots violating the established continuity.

Jumper (A/V, computer)
In communications a "Jumper" is a term sometimes used to describe a short cable with two connectors that connects to ports on a modular panel or between two devices.

In computers, a small plastic spring clip making an electrical connection between two adjacent square metal pins, usually in the form of a header. Jumpers are used to set device addresses, interrupt levels, and other options of adapter cards. They are also found on motherboards.

Junction (computer/microelectronics)
Joining of two different semiconductors or a joining of semiconductor and metal. Alloy, diffused, electrochemical, and grown, are the four junction fabrication types.

Junction Diode (computer/microelectronics)
Semiconductor rectifying device in which the barrier between two regions of opposite conductivity type produces the rectification. Junction diodes are used in computers, radio and television, brushless generators, battery chargers, and electrochemical processes requiring high direct current and low voltage.

Justification (computer)
In the context of programming, justification refers to the left or right alignment of a piece of information, typically a bit or character string, in a field that is assumed to be larger (greater in length) than the data. Right justifying a bit string of length 2 in an 8-bit byte means that the rightmost of the two data bits is placed in the rightmost position of the byte. In the context of text processing, justification is the left and/or right character justification and margin alignment.