JOYSTICK - A joystick is a two-dimensional potentiometer, an electromechanical input device with a vertical lever, pivoted so that it may be manipulated within 360 degrees. When connected to a computer via a cable, it can provide positional information for the movement of the cursor on a video display screen. The application program that is designed to receive input from a joystick, responds by moving a cursor or an image on the screen in the same direction as the movement of the joystick lever. Joysticks are primarily used to play video games.

JUMPER - Often on Printed Circuit Boards the designer will allow the board to be set-up in a variety of ways depending on the particular needs of the user. This is accomplished by placing a pair of jumper pins in the circuit. If a small plastic-covered metal clip is placed over the open pair of pins, the circuit becomes closed.

KB - KILOBYTE, A unit of measure for computer memory or storage equivalent to approximately one thousand (1,024) bytes. Two blocks.

LAN - Local Area Network - When two or more computers are linked together for the purpose of sharing information and/or peripheral devices, a network is created. When the network is confined to a geographically restricted area, such as within the same building or perhaps on a college campus, it is referred to as a Local Area Network. There are three types of data transmission media used on most of today's LANs: a twisted-pair of wires, coaxial cable, and the newest, fiber optical cable.

LASER PRINTER - A computer printer that uses the electrophotograhic method of printing (like a photocopier) with a laser beam as the light source. Laser printers produce high resolution copy and are especially popular with business users. Laser printers are also very quiet and usually faster than DMPs (Dot Matrix Printers).

LISP - List Processing. An interpreted programming language, first designed by John McCarthy at MIT. LISP is different from most programming languages in that programs and data structures are equivalent, and recursion is the principal control structure. It is widely used for artificial intelligence programming.

LOAD - to transfer information from mass storage (disk) into memory.

LOGICAL OPERATOR - an operator, such as AND, that combines logical values (true, false) to produce a logical result.

LOOP - a section of a program that is executed repeatedly until some condition is met.

LOOP, INFINITE - see INFINITE LOOP.

LOST CHAINS - A DOS utility program exists, called "CHKDSK" which performs an analysis of the integrity of the files on a hard disk. If all of the files and sub-directories are properly accounted for in the File Allocation Table (FAT), then CHKDSK provides information about the disk including its size, the number of files found, the amount of storage space remaining, and other useful data. If CHKDSK encounters a problem with one or more files, you may be presented with a message similar to this:

"5 lost allocation units found in 3 chains.

Convert lost chains to files (Y/N) ?"

This message indicates that portions of a file (or files) have become detached from the rest of the file or that a file has become separated from its directory entry. You have lost chains.

LPT1, LPT2, LPT3 - These are logical device names for parallel printers or ports. With DOS operating system, LPT1, LPT2, and LPT3 are reserved names for up to three parallel printer ports. LPT1 is usually the same as the primary DOS hard-copy output device PRN. UNIX uses 'lpr' as the acronym for the printer or printer port.

MACHINE LANGUAGE - the set of binary encoded instructions that actually are executed by the hardware of the computer.

MAINFRAME - Large computers are referred to as mainframes. More precisely, the mainframe is the piece of equipment on large computers that contains the CPU. Mainframe computers most commonly operate with word lengths of 32-bits or more, have large memory capacities, and are used where large volumes of data are stored and processed. The term 'mainframe' is really a holdover from the days when most computer systems occupied the space of several rooms. There really was a main frame, and several secondary frames or large rack and panel cabinets that held thousands of vacuum tubes.

MASS STORAGE - non-memory storage for data. Floppies are mass storage.

MB - MEGABYTE, A unit of measure for computer memory or storage equivalent to approximately one million (1,048,576) bytes.

MCA - IBM's proprietary Micro Channel Architecture is the data bus of their PS/2 line of microcomputers. This is the data bus of the computer that controls the flow of data between processors and to and from such peripheral devices as the keyboard, monitor, and printer. The Micro Channel has three main aspects: a 32-bit bandwidth, the I/O processors, and the multimaster control, which acts like a data traffic cop to allow multiprocessors to work simultaneously. Boards that plug into the MCA bus are not interchangeable those of standard PCs.

MEMORY - The area where your computer stores data. Data can be permanently stored in ROM (Read Only Memory) or stored temporarily in the computer's RAM (Random Access Memory). A computer's RAM storage space is emptied when the power is turned off; whereas ROMs will retain information with no power.

MEMORY MANAGER - A program that increases the amount of RAM available to programs by making by facilitating the use of Extended or Expanded memory . Some of the more common DOS Memory Managers are HIMEM.SYS, EMM386.EXE, QEMM.EXE, and products from other third party vendors. Not needed on a UNIX machine.

MENU - A list of available services or functions provided by an application program. One selects an option by using a mouse or arrow key to highlight it, and clicking the mouse or pressing Enter. Most menus are pull-down menus located at the top of the screen, and the options for a particular heading appear when that category is selected.

MHz - megahertz is a unit of frequency measurement. One Hertz (Hz) is equal to one cycle per second. Heinrich R. Hertz, a German physicist, first detected electromagnetic waves in 1883. 1 Megahertz is one million electrical vibration cycles per second. The original IBM-Personal Computers in the early 1980's were controlled by Central Processing Units (CPUs) that were synchronized with clock crystals vibrating at 4.77 MHz. Present PCs operate at frequencies as high as 200 MHz.

MICROPROCESSOR - A single large-scale integrated circuit containing all of the central processing functions of a computer. (See also CPU)

MIDI - Musical Instrument Digital Interface. An interface card or adapter board for connecting a musical instrument to a microcomputer is called a MIDI Adapter. Multiple musical instrument keyboards can be daisy-chained together and played simultaneously with the help of the computer and related software. The various operations of the musical keyboard can be captured, saved, edited, and played back to one or more musical instruments. Each instrument, of course, must be MIDI compatible. Music can be digitally recorded and then played back as new tracks are recorded, creating the sound of an entire orchestra.

MIME - Multipurpose Internet Mail Extensions. An encoding scheme for allowing non-ASCII data, such as word processor formatting, to be included in an e-mail message.

MIPS - Million Instructions Per Second. MIPS is a unit for measuring the average number of machine language instructions a computer can perform or execute in one second. However, it can be shown that the same computer can execute two different loops of code to estimate MIPS, and their execution times will differ significantly. A MIPS value should therefore be used only as a very general measure of performance when comparing different types of computers. In order to obtain accurate performance data to compare similar computers, each subsystem must be isolated, and practically speaking, this is an almost impossible task. More realistic benchmark testing occurs at the application level. MIPS is sometimes jokingly referred to as Meaningless Indicator of Processor Speed.

MODEM - Modulator-demodulator. A piece of computer hardware that allows a computer to communicate with other computers (if they also have a modem attached) via a telephone line. Originally, modems converted electrical signals to audio tones and sent them through a telephone mouthpiece; current modems introduce the electrical signals directly into the phone line.

MONITOR - the part of the computer containing the video display unit; so called because it allows you to monitor processes visually.

MOTHERBOARD - The printed circuit board that is the foundation of a PC or workstation system. This board contains the computer's CPU (Central Processing Unit), RAM (Random Access Memory) chips and expansion slots that enable one to add more functions/features to the machine.

MOUSE - A device about the size of the palm of your hand that one rolls around on a flat, smooth surface to move the computer's cursor (pointer) quickly over the screen. As the mouse moves, a plastic ball on the bottom creates signals that move the cursor on the screen. Clicking the buttons on the mouse sends signals equivalent to those that are generated by various keyboard combinations. For example, clicking the left button rapidly twice in succession usually is equivalent to pressing the Enter key. So named because its slender connecting cable reminded someone of a mouse's hairless tail.

MPC - Multimedia PC. A specification developed by Tandy(R) and Microsoft(R) for the minimum platform capable of running multimedia software. PCs carrying the MPC logo are able to run any software that also displays the MPC logo, which consists of rainbow-colored letters on a black background.

MULTIMEDIA - The presentation of information on a computer using a combination of sound, still graphics, animation and video.

MULTI SYNC monitor - A video display monitor that is capable of automatically adjusting to the synchronization frequency of the video board that is sending signals to it.

NESTED - contained within. A nested loop is one contained within, and executed within, another loop.

NETWORK - When two or more computers are linked together for the purpose of sharing information and/or peripheral devices, a network is created. A network is also a database design technique for managing a collection of related programs for loading, accessing, and controlling the information that makes up the database.

NIBBLE - half a byte.

NNTP - Network News Transfer Protocol. The protocols for dissemination of "news" articles (topical messages) via TCP/IP.

NODE - When any number of computers are connected together in a network, each of the workstations or terminals is referred to as a node, and is assigned a unique address within that network. A node is also an electrical connection point on a printed circuit board or component. With online services, a node is the local collection of relay modems.

NOT - a unary logical operator that produces a true result if its operand is false, and a false result if the operand is true.

NULL MODEM CABLE - The RS-232 standard defines two types of interfaces, data terminal equipment (DTE), and data communication equipment (DCE). Personal computers are almost always configured as DTE devices while a device like a modem or mouse is typically configured as a DCE device. When connecting two like devices, DTE to DTE or DCE to DCE, you must use a null modem cable or modem-eliminator adapter. The following list shows the pin to pin connections required to make a null modem cable between DB-25S and DB-25P connectors:

1-1, 2-3, 3-2, 4-5, 5-4, 6-20, 7-7, 20-6

[Index] [A-C] [D-E] [F-I] [J-N] [O-S] [T-Z