The unit of a computing system containing the circuits that performarithmetic and logical operations
pertaining to a characteristic or property involving a selection, choice,or condition in which there are two possibilities, or showing the datain base 2.
an electronic vacuum tube that displays the output of a computer signal
central processing unit (CPU)
the unit of a computer system that include the circuits that controlthe interpretation and execution of instruction. In many computer systems,the CPU includes the arithmetic logic unit, the control unit, and primarystorage unit.
client/server
a computing environment where end user workstations (clients) are connectedto micro or mini LAN servers and possibly to mainframe superservers
computer system
computer hardware as a system of input, processing, output, storage,and control components. Thus a computer system consists of input and outputdevices, primary and secondary storage devices, the central processingunit, the control unit within the CPU, and other peripheral devices
computer terminal
any input/output device connected by telecommunications links to a computer
control unit
a subunit of the central processing unit that controls and directs theoperations of the computer system. The control unit retrieves computerinstructions in proper sequence, interprets each instruction, and thendirects the other parts of the computer system in their implementation
a method of storage where each storage position has a unique addressand can be individually accessed in approximately the same period of timewithout having to search through other storage positions. The same as randomaccess.
direct input/output devices
devices such as terminals that allow data to be input into a computersystem or output from the computer system without use of machine-readablemedia distributed processing
a form of decentralization of information processing made possible bya network of computers dispersed throughout the organization. Processingof user applications is accomplished by several computers interconnectedby a telecommunications network, that relying on one large centralizedcomputer facility or on the decentralized operations of several independentcomputers
downsizing
moving to smaller computing platforms, such as mainframe systems tonetworks of personal computers and servers
a small figure on a video display that looks like a familiar officeorder device such as a file folder (for storing a file), a wastebasket(for deleting a file), or a calculator (for switching to a calculator mode.)
a photoelectronic device that allows data to be entered on the faceof a video display terminal
liquid crystal displays (LCD’s)
electronic visual displays that form characters by applying an electricalcharge to selected silicon crystals
local area network (LAN)
a communications network that typically connects computers, terminal,and other computerized devices within a limited physical area such as anoffice, building, manufacturing plant, or other worksite.
a flat circular plate with a magnetic surface of which data can be storedby selective magnetization of portions of the curved surface
floppy disk
a small plastic disk coated with iron oxide that resembles a small phonographrecord encoded in a protective enveloped. It is a widely used form of magneticdisk media that provide a direct access storage capability for microcomputersystems
hard disk
magnetic tape
a plastic tape with a magnetic surface on which data can be stored byselective magnetization of portions of the surface
mainframe computer
a large-size computer system, typically with a separate central processingunit, as distinguished from microcomputer and minicomputer
microcomputer
a very small computer, range in size from "computer on a chip"to a small typewriter size unit.
Microprocessor
a microcomputer central processing unit (CPU) on a chip. Without input/outputor primary storage capabilities in most types
midrange computer
a computer category between microcomputers and mainframes. Examplesinclude minicomputers, network servers, and technical stations.
Minicomputer
a small (e.g. the size of a desk0 electronic, digital, stored-program,general-purpose computer
multimedia presentations
providing information using a variety of media, including text and graphicsdisplays, voice and other audio, photographs, and video segments
multiprocessing
pertaining to the simultaneous execution of two or more instructionsby a computer or computer network
an interconnected system of computers, terminals, and communicationschannels and devices
off-line
pertaining to equipment or devices not under control of the centralprocessing unit
online
pertaining to equipment or devices under control of the central processingunit
optical character recognition (OCR)
the machine identification of printed characters through the use oflight sensitive devices
optical disk storage
a secondary storage medium using laser technology to read tiny spotson a plastic disk. The disks are currently capable of storing billionsof characters of information
CD-ROM
an optical disk technology for microcomputers featuring compact diskswith a storage capacity of over 500 megabytes
optical scanner
a device that optically scans characters or images and generates theirdigital representations
tablet-style microcomputers that recognize handwriting and hand drawingdone by a pen-shaped device on their pressure-sensitive display screens
peripheral devices
in a computer system, any unit of equipment, distinct from the centralprocessing unit, that provides the system with input, output, or storagecapabilities
plasma displays
output device that generate a visual display with electrically chargedparticles of gas trapped between glass plates
plotters
a hard-copy output device that produces drawings and graphical displayson paper or other materials
pointing devices
devices that allow end users to issue commands to make choices by movinga cursor on the display screen
mouse
a small device that is electronically connected to a computer and ismoved by hand on a flat surface in order to move the cursor on a videoscreen in the same direction. Buttons on the mouse allow users to issuecommands and make responses and selection.
pointing stick
a small buttonlike device on a keyboard which moves the cursor on thescreen in the direction of the pressure placed upon it
tracer ball
a rollerball device set in a case used to move the cursor on a computer’sdisplay screen
primary storage unit printers processing speeds secondary storage device
storage that supplements the primary storage of a computer. Synonymouswith auxiliary storage
microelectronics storage circuitry etched on tiny chips of silicon orother semiconducting material. The primary storage of most modern computersconsists of microelectronics semiconductor storage chips for random accessmemory (RRAM) and read only memory (ROM).
RAM: Random Access Memory. One of the basic typesof semiconductor memory used for temporary storage of data or programsduring processing. Each memory position can be directly sensed (read) orchanged (write) in the same length of time, irrespective of its locationon the storage medium.
ROM: Read Only Memory. A basic type of semiconductormemory used for permanent storage. Can only be read, not "written",that is, changed. Variations are Programmable Read Only Memory (PROM) andErasable Programmable Read Only Memory (EPROM).
sequential access
A sequential method of storing and retrieving data from a file.
storage capacity elements
bit: a contraction of "binary digit."It can have the value of 0 or 1.
Byte: a sequence of adjacent binary digits operatedon as a unit and usually shorter than a computer word. In many computersystems, a byte is a grouping of eight bits that can represent one alphabeticor special character or can be "packed’ with two decimal digits
kilobyte: megabyte: one million bytes. More accurately,2 to the 20th power, or 1,048,576 in decimal notation
gigabyte: one billion bytes or 2 to the 30th power
terabyte: on trillion bytes, or 2 to the 40th power,or 1,0009,5111,627,776 bytes in decimal form
supercomputer
a special category of large computer systems tat are the most powerfulavailable. They are designed to solve massive computational problems.
millisecond: a thousandth of a second
microsecond: a millionth of a second
nanosecond: one billionth of a second
picosecond: one trillionth of a second
touch-sensitive screen:
an input device that accepts data input by the placement of a fingeron or close to the CRT screen
voice recognition
direct conversation of spoken data into electronic form sizable forentry into a computer system. Also called voice data entry
voice response
volatile memory
memory (such as electronic semiconductor memory) that loses its contentswhen electrical power is interrupted
This page was created by David Lewis on 6/18/97