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Glossary Of Computer Terms
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E F G H I J K L M N O
P Q R S T U V W X Y Z
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Easter egg: n. A hidden feature of a computer program. It may be a hidden
command, an animation, a humorous message, or a list of credits for the people who developed the program. In order
to display an Easter egg, a user often must enter an obscure series of keystrokes.
EBCDIC: n. Acronym for Extended Binary Coded Decimal Interchange Code. An IBM
code that uses 8 bits to represent 256 possible characters (compared with unextended ASCII's 7 bits and 128 characters).
It is used primarily in IBM mainframes, whereas personal computers use ASCII. Compare ASCII.
e-bomb: n. Short for e-mail bomb. A technique used by some hackers in which
a target is put on a large number of mailing lists so that network traffic and storage are tied up by e-mail sent
by other mailing list subscribers to the lists' recipients.
ECC: See error-correcting code, error-correction coding.
echo1: n. In communications, a signal transmitted back to the sender that is
distinct from the original signal. Network connections can be tested by sending an echo back to the main computer.
echo2: vb. To transmit a received signal back to the sender. Computer programs,
such as MS-DOS and OS/2, can be commanded to echo input by displaying data on the screen as it is received from
the keyboard. Data communications circuits may echo text back to the originating terminal to confirm that it has
echo check: n. In communications, a method for verifying the accuracy of transmitted
data by retransmitting it to the sender, which compares the echoed signal with the original.
EDI: n. Acronym for electronic data interchange. A set of standards for controlling
the transfer of business documents, such as purchase orders and invoices, between computers. The goal of EDI is
the elimination of paperwork and increased response time. For EDI to be effective, users must agree on certain
standards for formatting and exchanging information, such as the X.400 protocol. See also CCITT X series, standard
edit: vb. 1. To make a change to an existing file or document. Changes to the
existing document are saved in memory or in a temporary file but are not added to the document until the program
is instructed to save them. Editing programs typically provide safeguards against inadvertent changes, such as
by requesting confirmation before saving under an existing filename, by allowing the user to assign a password
to a file, or by giving the option of setting the file to read-only status. 2. To run software that makes extensive,
predictable changes to a file automatically, such as a linker or a filter for graphics.
editing keys: n. A set of keys on some keyboards that assist in editing. Located
between the main keyboard and the numeric keypad, editing keys consist of three pairs: Insert and Delete, Home
and End, and Page Up and Page Down.
edit key: n. In a software application, a predefined key or combination of
keys that, when pressed, causes the application to enter edit mode.
edit mode: n. The mode of a program in which a user can make changes to a document,
as by inserting or deleting data or text. Compare command mode.
editor: n. A program that creates files or makes changes to existing files.
An editor is usually less powerful than a word processor, lacking the latter's capability for text formatting,
such as use of italics. Text or full-screen editors allow the user to move through the document using direction
arrows. In contrast, line editors require the user to indicate the line number on which text is to be edited. See
Edlin: n. An outdated line-by-line text editor used in MS-DOS through version
5. Its OS/2 counterpart is SSE. See also editor.
EDO DRAM: n. Acronym for extended data out dynamic random access memory. A
type of memory that allows for faster read times than DRAM of comparable speed by allowing a new read cycle to
begin while data is being read from a previous cycle. This allows for faster overall system performance. Compare
dynamic RAM, EDO RAM.
EDO RAM: n. Acronym for extended data out random access memory. A type of dynamic RAM that keeps data
available for the CPU while the next memory access is being initialized, resulting in increased speed. Pentium-class
computers using Intel's Triton chip set are designed to take advantage of EDO RAM. See also central processing
unit, dynamic RAM. Compare EDO DRAM.
edutainment: n. Multimedia content in software, on CD-ROM, or on a Web site
that purports to educate the user as well as entertain. See also multimedia.
EEMS: n. Acronym for Enhanced Expanded Memory Specification. A superset of
the original Expanded Memory Specification (EMS). Version 3.0 of EMS allowed only storage of data and supported
4-page frames. EEMS allowed up to 64 pages along with executable code to be stored in expanded memory. The features
of EEMS were included in EMS version 4.0. See also EMS, page frame.
EEPROM: n. Acronym for electrically erasable programmable read-only memory.
A type of EPROM that can be erased with an electrical signal. It is useful for stable storage for long periods
without electricity while still allowing reprogramming. EEPROM contain less memory than RAM, take longer to reprogram,
and can be reprogrammed only a limited number of times before wearing out. See also EPROM, ROM.
e-form: n. Short for electronic form. An online document that contains blank
spaces for a user to fill in with requested information and that can be submitted through a network to the organization
requesting the information. On the Web, e-forms are often coded in CGI and encrypted. See also CGI (definition
EGA: n. Acronym for Enhanced Graphics Adapter. An IBM video display standard introduced in 1984. It
emulates the Color/Graphics Adapter (CGA) and the Monochrome Display Adapter (MDA) and provides medium-resolution
text and graphics. It was superseded by Video Graphics Display (VGA).
EISA: n. Acronym for Extended Industry Standard Architecture. A bus standard
for the connection of add-on cards to a PC motherboard, such as video cards, internal modems, sound cards, drive
controllers, and cards that support other peripherals. EISA was introduced in 1988 by a consortium of nine computer
industry companies. The companies--AST Research, Compaq, Epson, Hewlett-Packard, NEC, Olivetti, Tandy, Wyse, and
Zenith--were referred to collectively as "the Gang of Nine." EISA maintains compatibility with the earlier
Industry Standard Architecture (ISA) but provides for additional features introduced by IBM in its Micro Channel
Architecture bus standard. EISA has a 32-bit data path, and it uses connectors that can accept ISA cards. However,
EISA cards are compatible only with EISA systems. EISA can operate at much higher frequencies than the ISA bus
and provides much faster data throughput than ISA. See also ISA, Micro Channel Architecture.
electromagnetic radiation: n. The propagation of a magnetic field through space.
Radio waves, light, and X rays are examples of electromagnetic radiation, all traveling at the speed of light.
electron gun: n. A device that produces an electron beam, typically found in
television or computer monitors. See also CRT.
electronic commerce: n. Commercial activity that takes place by means of connected
computers. Electronic commerce can occur between a user and a vendor through an online information service, the
Internet, or a BBS, or between vendor and customer computers through electronic data interchange (EDI). Also called
e-commerce. See also EDI.
electronic credit: n. A form of electronic commerce involving credit card transactions
carried out over the Internet. Also called e-credit. See also electronic commerce.
Electronic Frontier Foundation: n. A public advocacy organization dedicated
to the defense of civil liberties for computer users. The organization was founded in 1990 by Mitchell Kapor and
John Perry Barlow as a response to U.S. Secret Service raids on hackers. Acronym: EFF.
electronic mail services: n. Services that allow users, administrators, or
daemons to send, receive, and process e-mail. See also daemon.
electronic mall: n. A virtual collection of online businesses that affiliate
with the intention of increasing the exposure of each business through the fellow businesses.
electronic publishing: n. A general term for distributing information via electronic
media, such as communications networks or CD-ROM.
electronics: n. The branch of physics dealing with electrons, electronic devices,
and electrical circuits.
electronic software distribution: n. A means of directly distributing software
to users on line over the Internet. Electronic software distribution is analogous to direct-mail ordering. Acronym:
electronic storefront: n. A business that displays its merchandise on the Internet
and has provisions for contact or online sales.
ellipsis: n. A set of three dots (...) used to convey incompleteness. In many
windowing applications, selection of a command that is followed by an ellipsis will produce a submenu or a dialog
box. In programming and software manuals, an ellipsis in a syntax line indicates the repetition of certain elements.
See also dialog box, syntax.
e-mail1or email or E-mail: n. 1. The exchange of text messages and computer
files over a communications network, such as a local area network or the Internet, usually between computers or
terminals. 2. An electronic text message.
e-mail2 or email or E-mail: vb. To send an e-mail message.
e-mail address: n. A string that identifies a user so that the user can receive
Internet e-mail. An e-mail address typically consists of a name that identifies the user to the mail server, followed
by an at sign (@) and the host name and domain name of the mail server. For example, if Anne E. Oldhacker has an
account on the machine called baz at Foo Enterprises, she might have an e-mail address firstname.lastname@example.org, which would
be pronounced "A E O at baz dot foo dot com."
e-mail filter: n. A feature in e-mail-reading software that automatically sorts
incoming mail into different folders or mailboxes based on information contained in the message. For example, all
incoming mail from a user's Uncle Joe might be placed in a folder labeled "Uncle Joe." Filters may also
be used either to block or accept e-mail from designated sources.
embedded: adj. In software, pertaining to code or a command that is built into
its carrier. For example, application programs insert embedded printing commands into a document to control printing
and formatting. Low-level assembly language is embedded in higher-level languages, such as C, to provide more capabilities
or better efficiency.
embedded file: n. An image, sound, video or other file inserted on a page from
files or from the clipboard. When you save your file, embedded files are saved with the file.
embedded hyperlink: n. A link to a resource that is embedded within text or
is associated with an image or an image map. See also hyperlink, image map.
embedded style sheet: n. A cascading style sheet that is embedded on a page.
Styles in an embedded style sheet can be applied only to the page containing the style sheet, and will either extend
or override styles defined in any external style sheet that is linked to the page. Compare external style sheet.
See also cascading style sheet.
em dash: n. A punctuation mark (--) used to indicate a break or interruption
in a sentence. It is named for the em, a typographical unit of measure that in some fonts equals the width of a
capital M. Compare en dash, hyphen.
EMM: n. See Expanded Memory Manager.
e-money: or emoney n. Short for electronic money. A generic name for the exchange
of money through the Internet. Also called cybercash, digicash, digital cash, e-cash.
emoticon: n. A string of text characters that, when viewed sideways, form a
face expressing a particular emotion. An emoticon is often used in an e-mail message or newsgroup post as a comment
on the text that precedes it. Common emoticons include :-) or :) (meaning "I'm smiling at the joke here"),
;-) ("I'm winking and grinning at the joke here"), :-( ("I'm sad about this"), :-7 ("I'm
speaking with tongue in cheek"), :D or :-D (big smile; "I'm overjoyed"), and :-O (either a yawn
of boredom or a mouth open in amazement). Compare emotag.
EMS: n. Acronym for Expanded Memory Specification. A technique for adding memory
to PCs that allows for increasing memory beyond the Intel 80x86 microprocessor real-mode limit of 1 megabyte. In
earlier versions, EMS bypassed this memory board limit with a number of 16-kilobyte banks of RAM that could be
accessed by software. In later versions of Intel microprocessors, including the 80386 and 80486 models, EMS is
converted from extended memory by software memory managers, such as EMM386 in MS-DOS 5. Now EMS is used mainly
for older MS-DOS applications because Windows and other applications running in protected mode on 80386 and higher
microprocessors are free of the 1-MB limit. Also called LIM EMS. See also expanded memory, protected mode. Compare
conventional memory, extended memory.
em space: n. A typographical unit of measure that is equal in width to the
point size of a particular font. For many fonts, this is equal to the width of a capital M, from which the em space
takes its name. Compare en space, fixed space, thin space.
emulate: vb. For a hardware or software system to behave in the same manner
as another hardware or software system. In a network, microcomputers often emulate mainframes or terminals so that
two machines can communicate.
emulation: n. The process of a computer, device, or program imitating the function
of another computer, device, or program.
enable: vb. To activate or turn on. Compare disable.
encapsulate: vb. To treat a collection of structured information as a whole
without affecting or taking notice of its internal structure. In communications, a message or packet constructed
according to one protocol, such as a TCP/IP packet, may be taken with its formatting data as an undifferentiated
stream of bits that is then broken up and packaged according to a lower-level protocol (for example, as ATM packets)
to be sent over a particular network; at the destination, the lower-level packets are assembled, re-creating the
message as formatted for the encapsulated protocol. In object-oriented programming, the implementation details
of a class are encapsulated in a separate file whose contents do not need to be known by a programmer using that
class. See also ATM (definition 1), object-oriented programming, TCP/IP.
Encapsulated PostScript: n. See EPS.
encode: vb. 1. In data security, to encrypt. See also encryption. 2. In programming,
to put something into code, which frequently involves changing the form--for example, changing a decimal number
to binary-coded form. See also binary-coded decimal, EBCDIC.
encryption: n. The process of encoding data to prevent unauthorized access,
especially during transmission. Encryption is usually based on a key that is essential for decoding. The U.S. National
Bureau of Standards created a complex encryption standard, Data Encryption Standard (DES), which provides almost
unlimited ways to encrypt documents. See also DES.
encryption key: n. A sequence of data that is used to encrypt other data and
that, consequently, must be used for the data's decryption. See also decryption, encryption.
endless loop: n. See infinite loop.
end-of-file: n. A code placed by a program after the last byte of a file to tell the computer's operating
system that no additional data follows. In ASCII, end-of-file is represented by the decimal value 26 (hexadecimal
1A) or the Ctrl-Z control character. Acronym: EOF.
End-User License Agreement: n. A legal agreement between a software manufacturer
and the software's purchaser with regard to terms of distribution, resale, and restricted use. Acronym: EULA.
Energy Star: n. A symbol affixed to systems and components that denotes lower
power-consumption design. Energy Star is the name of an Environmental Protection Agency program that encourages
PC manufacturers to build systems that are energy efficient. Requirements dictate that systems or monitors be capable
of automatically entering a lower power-consumption state or "sleep state" while the unit is inactive,
where the low-power state is defined as 30 watts or less. Systems and monitors that comply with these guidelines
are marked with an Energy Star sticker.
engine: n. A processor or portion of a program that determines how the program
manages and manipulates data. The term engine is most often used in relation to a specific program; for example,
a database engine contains the tools for manipulating a database. Compare back-end processor, front-end processor.
Enhanced Graphics Display: n. A PC video display capable of producing graphic
images with resolutions ranging from 320 × 200 to 640 × 400 pixels, in color or in black and white.
Resolution and color depth depend on the vertical and horizontal scanning frequencies of the display, the capabilities
of the video display controller card, and available video RAM.
Enhanced IDE: n. Short for Enhanced Integrated Drive Electronics. An extension
of the IDE standard, Enhanced IDE is a hardware interface standard for disk drive designs that house control circuits
in the drives themselves. It allows for standardized interfaces to the system bus while providing for advanced
features, such as burst data transfer and direct data access. Enhanced IDE accommodates drives as large as 8.4
gigabytes (IDE supports up to 528 megabytes). It supports the ATA-2 interface, which permits transfer rates up
to 13.3 megabytes per second (IDE permits up to 3.3 megabytes per second), and the ATAPI interface, which connects
drives for CD-ROMs, optical discs and tapes, and multiple channels. Most PCs have Enhanced IDE drives, which are
cheaper than SCSI drives and provide much of the same functionality. See also IDE, SCSI. Acronym: EIDE.
enhanced keyboard: n. An IBM 101/102-key keyboard that replaced the PC and
AT keyboards. It features 12 function keys across the top (rather than 10 on the left side), extra Control and
Alt keys, and a bank of cursor and editing keys between the main keyboard and number pad. It is similar to the
Apple Extended Keyboard.
enhanced parallel port: n. A connection port for peripheral devices, most often
used for printers, external disk drives, or tape drives. Enhanced parallel ports utilize high-speed circuits for
faster data throughput. Data and communications control lines are wired in parallel; each data line corresponds
to 1 data bit. Data is transferred across all lines in sync. See also input/output port. Acronym: EPP.
enhanced serial port: n. A connection port for peripheral devices, commonly
used for mice and external modems. Enhanced serial ports utilize 16550-type or newer high-speed UART circuits for
faster data throughput. Data is transferred as a sequence of bits and bytes on a pair of lines, either synchronously
(data flows in one direction only) or asynchronously (data flows each way in turn). See also input/output port,
UART. Acronym: ESP.
ENIAC: n. An 1800-square-foot, 30-ton computer containing 17,468 vacuum tubes and 6,000 manual switches.
Developed between 1942 and 1946 for the U.S. Army by J. Presper Eckert and John Mauchly at the University of Pennsylvania,
ENIAC is considered to have been the first truly electronic computer. It remained in operation until 1955.
enlarge: vb. In Microsoft Windows and other graphical user interfaces, to increase
the size of a window. See also maximize. Compare minimize, reduce.
E notation: n. See floating-point notation.
Enter key: n. The key that is used at the end of a line or command to instruct
the computer to process the command or text. In word processing programs, the Enter key is used at the end of a
paragraph. Also called Return key.
enterprise computing: n. In a large enterprise such as a corporation, the use
of computers in a network or series of interconnected networks that generally encompass a variety of different
platforms, operating systems, protocols, and network architectures. Also called enterprise networking.
enterprise network: n. In a large enterprise such as a corporation, the network
(or interconnected networks) of computer systems owned by the enterprise, which fills the enterprise's various
computing needs. This network can span diverse geographical locations and usually encompasses a range of platforms,
operating systems, protocols, and network architectures.
EOL: n. Acronym for end of line. A control (nonprinting) character that signals
the end of a data line in a data file.
EOT: n. See end-of-transmission.
EPP IEEE standard: n. An IEEE standard relating to the Enhanced Parallel Port (EPP) protocol. This protocol
was originally developed by Intel, Xircom, and Zenith Data Systems as a means to provide a high-performance parallel
port link that would still be compatible with the standard parallel port. This protocol capability was implemented
by Intel in the 386SL chip set (82360 I/O chip), prior to the establishment of the IEEE 1284 committee and the
associated standards work. The EPP protocol offered many advantages to parallel port peripheral manufacturers and
was quickly adopted by many as an optional data transfer method. A loose association of around 80 interested manufacturers
was formed to develop and promote the EPP protocol. This association became the EPP Committee and was instrumental
in helping to get this protocol adopted as one of the IEEE 1284 advanced modes. See also IEEE, parallel port, protocol.
EPROM: n. Acronym for erasable programmable read-only memory. A nonvolatile
memory chip that is programmed after it is manufactured. EPROMs can be reprogrammed by removing the protective
cover from the top of the chip and exposing the chip to ultraviolet light. Though EPROMS are more expensive than
PROM chips, they can be more cost-effective if many changes are required. Also called reprogrammable read-only
memory (RPROM). See also EEPROM, PROM, ROM.
EPS: n. Acronym for Encapsulated PostScript. A PostScript file format that
can be used as an independent entity. The EPS image must be incorporated into the PostScript output of an application
such as a desktop publisher. Many high-quality clip-art packages consist of such images. See also PostScript.
erase: vb. To remove data permanently from a storage medium. This is usually
done by replacing existing data with zeros or meaningless text or, in magnetic media, by disturbing the magnetic
particles' physical arrangement, either with the erase head or with a large magnet. Erase differs from delete in
that delete merely tells the computer that data or a file is no longer needed; the data remains stored and is recoverable
until the operating system reuses the space containing the deleted file. Erase, on the other hand, removes data
permanently. See also erase head. Compare delete.
erase head: n. The device in a magnetic tape machine that erases previously
ergonomic keyboard: n. A keyboard designed to reduce the risk of wrist and
hand injuries that result from prolonged use or repetitive movement. An ergonomic keyboard can include such features
as alternative key layouts and palm rests. See also Dvorak keyboard, keyboard, Kinesis ergonomic keyboard.
ergonomics: n. The study of people (their physical characteristics and the
ways they function) in relation to their working environment (the furnishings and machines they use). The goal
of ergonomics is to incorporate comfort, efficiency, and safety into the design of keyboards, computer desks, chairs,
and other items in the workplace.
error: n. A value or condition that is not consistent with the true, specified,
or expected value or condition. In computers, an error results when an event does not occur as expected or when
impossible or illegal maneuvers are attempted. In data communications, an error occurs when there is a discrepancy
between the transmitted and received data. See also critical error, error message, error rate, error ratio, fatal
error, hard error, inherent error, intermittent error, logic error, machine error, overflow error, parity error,
propagated error, read error, recoverable error, syntax error, system error, write error. Compare fault.
error checking: n. A method for detecting discrepancies between transmitted
and received data during file transfer.
error detection and correction: n. A method for discovering and resolving errors
during file transfer. Some programs only detect errors; others detect and attempt to fix them.
error file: n. A file that records the time and type of data processing and
error handling: n. The process of dealing with errors (or exceptions) as they
arise during the running of a program. Some programming languages, such as C++, Ada, and Eiffel, have features
that aid in error handling. See also bug (definition 1).
error message: n. A message from the system or program indicating that an error
requiring resolution has occurred.
escape code: n. A character or sequence of characters that indicates that a
following character in a data stream is not to be processed in the ordinary way. In the C programming language,
the escape code is the backslash \, which has several uses, as shown by the statement printf ("The backslash
\"\\\" is the escape code.\n") ;. The last backslash, which is the next-to-last character in the
string, indicates that the following n is not to be printed but that the sequence \n represents the newline character.
By contrast, the backslashes before the quotation marks indicate that the latter are to be printed, rather than
marking the end of one string and the beginning of another; similarly, the backslash before a backslash indicates
that the second backslash is to be printed, rather than serving as an escape code. The resulting output is The
backslash"\" is the escape code.
Escape key: n. A key on a computer keyboard that sends the escape (ESC) character
to the computer. In many applications, the Escape key moves the user back one level in the menu structure or exits
the program. See also Clear key.
escape sequence: n. A sequence of characters that usually begins with the ESC
character (ASCII 27, hexadecimal 1B), which is followed by one or more additional characters. An escape sequence
escapes from the normal sequence of characters (such as text) and issues an instruction or command to a device
ESC character: n. One of the 32 control codes defined in the ASCII character
set. It usually indicates the beginning of an escape sequence (a string of characters that give instructions to
a device such as a printer). It is represented internally as character code 27 (hexadecimal 1B) Also called escape
ESDI: n. Acronym for Enhanced Small Device Interface. A device that allows
disks to communicate with computers at high speeds. ESDI drives typically transfer data at about 10 megabits per
second, but they are capable of doubling that speed.
ESP: n. See enhanced serial port.
ESP IEEE standard: n. Short for Encapsulating Security Payload IEEE standard.
A standard for providing integrity and confidentiality to IP (Internet Protocol) datagrams. In some circumstances,
it can also provide authentication to IP datagrams. See also authentication, datagram, IEEE, IP.
e-text: n. Short for electronic text. A book or other text-based work that
is available on line in an electronic media format. An e-text can be read on line or downloaded to a user's computer
for offline reading. See also ezine.
Ethernet: n. 1. An IEEE 802.3 standard for contention networks. Ethernet uses
a bus or star topology and relies on the form of access known as Carrier Sense Multiple Access with Collision Detection
(CSMA/CD) to regulate communication line traffic. Network nodes are linked by coaxial cable, by fiber-optic cable,
or by twisted-pair wiring. Data is transmitted in variable-length frames containing delivery and control information
and up to 1500 bytes of data. The Ethernet standard provides for baseband transmission at 10 megabits (10 million
bits) per second. See also 10Base2, 10Base5, 10BaseF, 10BaseT, baseband, bus network, coaxial cable, contention,
CSMA/CD, IEEE 802 standards, twisted-pair cable. 2. A widely used local area network system developed by Xerox
in 1976, from which the IEEE 802.3 standard was developed.
Ethernet/802.3: n. The IEEE standard for 10- or 100-Mbps transmissions over
an Ethernet network. Ethernet/802.3 defines both hardware and data packet construction specifications.
Eudora: n. An e-mail client program originally developed as freeware for Macintosh
computers by Steve Dorner at the University of Illinois, now maintained in both freeware and commercial versions
for both Macintosh and Windows by Qualcomm, Inc.
EULA: n. See End-User License Agreement.
evaluation: n. The determination, by a program, of the value of an expression
or the action that a program statement specifies. Evaluation can take place at compile time or at run time.
exa-: prefix Abbreviated E. A prefix meaning one quintillion (1018). In computing,
which is based on the binary (base-2) numbering system, exa- has a literal value of 1,152,921,504,606,846,976,
which is the power of 2 (260) closest to one quintillion.
exabyte: n. Abbreviated EB. Roughly 1 quintillion bytes, or a billion billion
bytes, or 1,152,921,504,606,846,976 bytes.
exception: n. In programming, a problem or change in conditions that causes
the microprocessor to stop what it is doing and handle the situation in a separate routine. An exception is similar
to an interrupt; both refer the microprocessor to a separate set of instructions. See also interrupt.
exception error 12: n. An error created in DOS environments caused by a stack
overflow. This problem may be corrected by modifying the CONFIG.SYS file and editing the STACKS= entries.
executable1: adj. Of, pertaining to, or being a program file that can be run.
Executable files have extensions such as .bat, .com, and .exe.
executable2: n. A program file that can be run, such as file0.bat, file1.exe,
executable program: n. A program that can be run. The term usually applies
to a compiled program translated into machine code in a format that can be loaded into memory and run by a computer's
processor. In interpreter languages, an executable program can be source code in the proper format. See also code
(definition 1), compiler (definition 2), computer program, interpreter, source code.
execute: vb. To perform an instruction. In programming, execution implies loading
the machine code of the program into memory and then performing the instructions.
exit: vb. In a program, to move from the called routine back to the calling
routine. A routine can have more than one exit point, thus allowing termination based on various conditions.
expanded: adj. A font style that sets characters farther apart than the normal
spacing. Compare condensed.
expanded memory: n. A type of memory, up to 8 MB, that can be added to IBM
PCs. Its use is defined by the Expanded Memory Specification (EMS). Expanded memory is not accessible to programs
in MS-DOS, so the Expanded Memory Manager (EMM) maps pages (blocks) of bytes from expanded memory into page frames
in accessible memory areas. See also EEMS, EMS, Expanded Memory Manager, page frame.
Expanded Memory Manager: n. A driver that implements the software portion of the Expanded Memory Specification
(EMS) to make expanded memory in IBM and compatible PCs accessible. See also EMS, expanded memory, extended memory.
expansion: n. A way of increasing a computer's capabilities by adding hardware
that performs tasks that are not part of the basic system. Expansion is usually achieved by plugging printed circuit
boards (expansion boards) into openings (expansion slots) inside the computer. See also expansion board, expansion
slot, open architecture (definition 2), PC Card, PCMCIA slot.
expansion board: n. A circuit board that is plugged into a computer's bus (main
data transfer path) to add extra functions or resources to the computer. Typical expansion boards add memory, disk
drive controllers, video support, parallel and serial ports, and internal modems. For laptops and other portable
computers, expansion boards come in credit card-sized devices called PC Cards that plug into a slot in the side
or back of the computer. Also called expansion board, extender board. See also expansion slot, PC Card, PCMCIA
expansion slot: n. A socket in a computer, designed to hold expansion boards
and connect them to the system bus (data pathway). Expansion slots are a means of adding or enhancing the computer's
features and capabilities. In laptop and other portable computers, expansion slots come in the form of PCMCIA slots
designed to accept PC Cards. See also expansion board, PC Card, PCMCIA slot.
expert system: n. An application program that makes decisions or solves problems
in a particular field, such as finance or medicine, by using knowledge and analytical rules defined by experts
in the field. It uses two components, a knowledge base and an inference engine, to form conclusions. Additional
tools include user interfaces and explanation facilities, which enable the system to justify or explain its conclusions
as well as allowing developers to run checks on the operating system. See also artificial intelligence, inference
engine, intelligent database, knowledge base.
expiration date: n. The date on which a shareware, beta, or trial version of
a program stops functioning, pending purchase of the full version or the entry of an access code.
Explorer: n. See Internet Explorer, Windows Explorer.
export: vb. To move information from one system or program to another. Files
that consist only of text can be exported in ASCII (plain text format). For files with graphics, however, the receiving
system or program must offer some support for the exported file's format. See also EPS, PICT, TIFF. Compare import.
extended ASCII: n. Any set of characters assigned to ASCII values between decimal 128 and 255 (hexadecimal
80 through FF). The specific characters assigned to the extended ASCII codes vary between computers and between
programs, fonts, or graphics characters. Extended ASCII adds capability by allowing for 128 additional characters,
such as accented letters, graphics characters, and special symbols. See also ASCII.
extended characters: n. Any of the 128 additional characters in the extended
ASCII (8-bit) character set. These characters include those used in several foreign languages, such as accent marks,
and special symbols used for creating pictures. See also extended ASCII.
extended memory: n. System memory beyond 1 megabyte in computers based on the
Intel 8086 processors. This memory is accessible only when an 80386 or higher-level processor is operating in protected
mode or in emulation on the 80286. To use extended memory, MS-DOS programs need the aid of software that temporarily
places the processor into protected mode or by the use of features in the 80386 or higher-level processors to remap
portions of extended memory into conventional memory. Programs running under Microsoft Windows, OS/2, and other
operating systems that run on Intel processors and use the protected mode of the 80386 and higher-level processors
can access all system memory in the same way. See also EMS, extended memory specification, protected mode.
extended memory specification: n. A specification developed by Lotus, Intel,
Microsoft, and AST Research that defines a software interface allowing real-mode applications to use extended memory
and areas of memory not managed by MS-DOS. Memory is managed by an installable device driver, the Expanded Memory
Manager (EMM). The application must use the driver to access the additional memory. See also Expanded Memory Manager,
extended memory. Acronym: XMS.
extended VGA: n. An enhanced set of Video Graphics Array (VGA) standards that
is capable of displaying an image of from 800 × 600 pixels to 1600 × 1200 pixels and that can support
a palette of up to 16.7 million (224) colors. This palette approaches the 19 million colors that a normal person
can distinguish, so it is considered a digital standard for color realism that parallels analog television. Also
called Super VGA, SVGA. See also analog-to-digital converter, CRT, VGA.
extension manager: n. On the Macintosh, a utility that allows the user to determine
which extensions are loaded when the computer is turned on. See also extension (definition 4).
External Gateway Protocol: n. A protocol for distributing information regarding
availability to the routers and gateways that interconnect networks. See also gateway, router. Acronym: EGP.
external hard disk: n. A free-standing hard disk with its own case and power
supply, connected to the computer with a data cable and used mainly as a portable unit. See also hard disk.
external modem: n. A stand-alone modem that is connected via cable to a computer's
serial port. See also internal modem.
external style sheet: n. A cascading style sheet is a file with a .css file
extension. The .css file is comprised solely of style rules in valid .css syntax, without any surrounding HTML
tags. By defining styles in one or more external style sheets and linking them to pages in your web, you ensure
consistency of appearance throughout those pages. If you change a style in the external style sheet, the change
will be reflected in all of the pages linked to that style sheet. Compare embedded style sheet. See also cascading
extract: vb. 1. To remove or duplicate items from a larger group in a systematic
manner. 2. In programming, to derive one set of characters from another by using a mask (pattern) that determines
which characters to remove.
ezine: n. Short for electronic magazine. A digital production available on
the Internet, a BBS, or other online service, often free of charge.
Many definitions maybe similar to the Microsoft Computer Dictionary,
5th Edition. Purchase information found at Microsoft Press.
The contributors of these definitions is far too numerous to mention, however
if you see something that you feel shouldn't be here let us know.