1. <operating system> A task running in the background (a
	background task) is detached from the terminal where it was
	started (and often running at a lower priority); opposite of
	{foreground}.  This means that the task's input and output
	must be from/to files (or other processes).

	Nowadays this term is primarily associated with {Unix}, but it
	appears to have been first used in this sense on {OS/360}.

	Compare {amp off}, {batch}, {slopsucker}.

	2. <jargon> For a human to do a task "in the background" is to
	do it whenever {foreground} matters are not claiming your
	undivided attention, and "to background" something means to
	relegate it to a lower priority.  "For now, we'll just print a
	list of nodes and links; I'm working on the graph-printing
	problem in the background."  Note that this implies ongoing
	activity but at a reduced level or in spare time, in contrast
	to mainstream "back burner" (which connotes benign neglect
	until some future resumption of activity).  Some people prefer
	to use the term for processing that they have queued up for
	their unconscious minds (often a fruitful tack to take upon
	encountering an obstacle in creative work).

	(1996-05-28)

See {safe}, {safety-critical system}.

1. The {supervisor} program or {operating system} on a
	computer.

	2. The entire computer system, including input/output devices,
	the {supervisor} program or {operating system} and possibly
	other {software}.

	3. Any large program.

	4. Any method or {algorithm}.

	[{Jargon File}]

<data, data processing, jargon> /day't*/ (Or "raw data")
	Numbers, {characters}, {images}, or other method of recording,
	in a form which can be assessed by a human or (especially)
	input into a {computer}, stored and {processed} there, or
	transmitted on some {digital channel}.  Computers nearly
	always represent data in {binary}.

	Data on its own has no meaning, only when interpreted by some
	kind of {data processing system} does it take on meaning and
	become {information}.

	People or computers can find patterns in data to perceive
	information, and information can be used to enhance
	{knowledge}.  Since knowledge is prerequisite to wisdom, we
	always want more data and information.  But, as modern
	societies verge on {information overload}, we especially need
	better ways to find patterns.

	1234567.89 is data.

	"Your bank balance has jumped 8087% to $1234567.89" is
	information.

	"Nobody owes me that much money" is knowledge.

	"I'd better talk to the bank before I spend it, because of
	what has happened to other people" is wisdom.

	(1999-04-30)

<programming> (Or "computer program", "program", "code") The
	instructions executed by a computer, as opposed to the
	physical device on which they run (the "{hardware}").

	The term was coined by the eminent statistician, {John Tukey}.

	Programs stored on {non-volatile storage} built from
	{integrated circuits} (e.g. {ROM} or {PROM}) are usually
	called {firmware}.

	Software can be split into two main types - {system software}
	and application software or {application programs}.  System
	software is any software required to support the production or
	execution of application programs but which is not specific to
	any particular application.  Examples of system software would
	include the {operating system}, {compilers}, editors and
	sorting programs.

	Examples of application programs would include an accounts
	package or a {CAD} program.  Other broad classes of
	application software include {real-time} software, {business
	software}, scientific and engineering software, {embedded
	software}, personal computer software and {artificial
	intelligence} software.

	Software includes both {source code} written by humans and
	executable {machine code} produced by {assemblers} or
	{compilers}.  It does not usually include the data processed
	by programs unless this is in a format such as {multimedia}
	which depends on the use of computers for its presentation.
	This distinction becomes unclear in cases such as {spread
	sheets} which can contain both instructions (formulae and
	{macros}) and data.  There are also various intermediate
	compiled or {semi-compiled}, forms of software such as
	{library} files and {byte-code}.

	Some claim that {documentation} (both paper and electronic) is
	also software.  Others go further and define software to be
	programs plus documentation though this does not correspond
	with common usage.

	The noun "program" describes a single, complete and
	more-or-less self-contained list of instructions, often stored
	in a single {file}, whereas "code" and "software" are
	uncountable nouns describing some number of instructions which
	may constitute one or more programs or part thereof.  Most
	programs, however, rely heavily on various kinds of {operating
	system} software for their execution.  The nounds "code" and
	"software" both refer to the same thing but "code" tends to
	suggest an interest in the implementation details whereas
	"software" is more of a user's term.

	(2002-07-21)

<language> (After {Ada Lovelace}) A {Pascal}-descended
	language, designed by Jean Ichbiah's team at {CII Honeywell}
	in 1979, made mandatory for Department of Defense software
	projects by the Pentagon.  The original language was
	standardised as "Ada 83", the latest is "{Ada 95}".

	Ada is a large, complex, {block-structured} language aimed
	primarily at {embedded} applications.  It has facilities for
	{real-time} response, {concurrency}, hardware access and
	reliable run-time error handling.  In support of large-scale
	{software engineering}, it emphasises {strong typing}, {data
	abstraction} and {encapsulation}.  The type system uses {name
	equivalence} and includes both {subtypes} and {derived types}.
	Both fixed and {floating-point} numerical types are supported.

	{Control flow} is fully bracketed: if-then-elsif-end if,
	case-is-when-end case, loop-exit-end loop, goto.  Subprogram
	parameters are in, out, or inout.  Variables imported from
	other packages may be hidden or directly visible.  Operators
	may be {overloaded} and so may {enumeration} literals.  There
	are user-defined {exceptions} and {exception handlers}.

	An Ada program consists of a set of packages encapsulating
	data objects and their related operations.  A package has a
	separately compilable body and interface.  Ada permits
	{generic packages} and subroutines, possibly parametrised.

	Ada support {single inheritance}, using "tagged types" which
	are types that can be extended via {inheritance}.

	Ada programming places a heavy emphasis on {multitasking}.
	Tasks are synchronised by the {rendezvous}, in which a task
	waits for one of its subroutines to be executed by another.
	The conditional entry makes it possible for a task to test
	whether an entry is ready.  The selective wait waits for
	either of two entries or waits for a limited time.

	Ada is often criticised, especially for its size and
	complexity, and this is attributed to its having been designed
	by committee.  In fact, both Ada 83 and Ada 95 were designed
	by small design teams to be internally consistent and tightly
	integrated.  By contrast, two possible competitors, {Fortran
	90} and {C++} have both become products designed by large and
	disparate volunteer committees.

	See also {Ada/Ed}, {Toy/Ada}.

	{Home of the Brave Ada Programmers
	(http://lglwww.epfl.ch/Ada/)}.  {Ada FAQs
	(http://lglwww.epfl.ch/Ada/FAQ/)} (hypertext), {text only
	(ftp://lglftp.epfl.ch/pub/Ada/FAQ)}.

	{(http://wuarchive.wustl.edu/languages/ada/)},
	{(ftp://ajpo.sei.cmu.edu/)},
	{(ftp://stars.rosslyn.unisys.com/pub/ACE_8.0)}.

	E-mail: <adainfo@ajpo.sei.cmu.edu>.

	{Usenet} newsgroup: {news:comp.lang.ada}.

	{An Ada grammar (ftp://primost.cs.wisc.edu/)} including a lex
	scanner and yacc parser is available.  E-mail:
	<masticol@dumas.rutgers.edu>.

	{Another yacc grammar and parser for Ada by Herman Fischer
	(ftp://wsmr-simtel20.army.mil/PD2:<ADA.EXTERNAL-TOOLS>GRAM2.SRC)}.

	An {LR parser} and {pretty-printer} for {Ada} from NASA is
	available from the {Ada Software Repository}.

	{Adamakegen} generates {makefiles} for {Ada} programs.

	["Reference Manual for the Ada Programming Language", ANSI/MIL
	STD 1815A, US DoD (Jan 1983)].  Earlier draft versions
	appeared in July 1980 and July 1982.  ISO 1987.

	[{Jargon File}]

	(2000-08-12)