<programming> (Or "remark") Explanatory text embedded in
	program {source} (or less often data) intended to help human
	readers understand it.

	Code completely without comments is often hard to read, but
	too heavily commented code isn't much better, especially if
	the comments are not kept up-to-date with changes to the code.
	Too much commenting may mean that the code is
	over-complicated.  A good rule is to comment everything that
	needs it but write code that doesn't need much of it.

	A particularly irksome form of over-commenting explains
	exactly what each statement does, even when it is obvious to
	any reasonably competant programmer, e.g.

		/* Open the input file */
		infd = open(input_file, O_RDONLY);

	(1998-04-28)

1. <storage> {Main memory} or {RAM}.  This term dates from the
	days of {ferrite core memory}; now archaic most places outside
	{IBM}, but also still used in the {Unix} community and by
	old-time {hackers} or those who would sound like them.

	Some derived idioms are quite current; "in core", for example,
	means "in memory" ({paged in}, as opposed to "on disk", {paged
	out}), and both {core dump} and the "core image" or "core
	file" produced by one are terms in favour.  Some varieties of
	Commonwealth hackish prefer {store}.

	[{Jargon File}]

	(1995-03-03)

	2. <processor> An {integrated circuit} design, usually for a
	{microprocessor}, which includes only the {CPU} and which is
	intended to form part of a complete circuit design which
	incorporates other circuits on the same chip such as {cache},
	{memory management unit}, I/O ports and timers.

	The {ARM6}, {ARM7} and {ARM8} are examples.

	3. <language> A varient on {kernel} as used to describe
	features built into a language as opposed to those provided by
	{libraries}.

	(1995-03-03)

<operating system> (GUI) The use of pictures rather than just
	words to represent the input and output of a program.  A
	program with a GUI runs under some {windowing system}
	(e.g. The {X Window System}, {MacOS}, {Microsoft Windows},
	{Acorn} {RISC OS}, {NEXTSTEP}).  The program displays certain
	{icons}, {buttons}, {dialogue boxes}, etc. in its {windows} on
	the screen and the user controls it mainly by moving a
	{pointer} on the screen (typically controlled by a {mouse})
	and selecting certain objects by pressing buttons on the mouse
	while the pointer is pointing at them.  This contrasts with a
	{command line interface} where communication is by exchange of
	strings of text.

	Windowing systems started with the first {real}-time graphic
	display systems for computers, namely the {SAGE} Project
	[Dates?] and {Ivan Sutherland}'s {Sketchpad} (1963).  {Douglas
	Engelbart}'s {Augmentation of Human Intellect} project at
	{SRI} in the 1960s developed the {On-Line System}, which
	incorporated a mouse-driven cursor and multiple windows.
	Several people from Engelbart's project went to Xerox PARC in
	the early 1970s, most importantly his senior engineer, {Bill
	English}.  The Xerox PARC team established the {WIMP} concept,
	which appeared commercially in the {Xerox 8010} (Star) system
	in 1981.

	Beginning in 1980(?), led by {Jef Raskin}, the {Macintosh}
	team at {Apple Computer} (which included former members of the
	Xerox PARC group) continued to develop such ideas in the first
	commercially successful product to use a GUI, the Apple
	Macintosh, released in January 1984.  In 2001 Apple introduced
	{Mac OS X}.

	{Microsoft} modeled the first version of {Windows}, released
	in 1985, on Mac OS.  Windows was a GUI for {MS-DOS} that had
	been shipped with {IBM PC} and compatible computers since
	1981.  Apple sued Microsoft over infringement of the
	look-and-feel of the MacOS.  The court case ran for many
	years.

	[Wikipedia].

	(2002-03-25)

<process> The approach that engineering (and some other)
	disciplines use to specify how to create or do something.  A
	successful design must satisfies a (perhaps informal)
	{functional specification} (do what it was designed to do);
	conforms to the limitations of the target medium (it is
	possible to implement); meets implicit or explicit
	requirements on performance and resource usage (it is
	efficient enough).

	A design may also have to satisfy restrictions on the design
	process itself, such as its length or cost, or the tools
	available for doing the design.

	In the {software life-cycle}, design follows {requirements
	analysis} and is followed by implementation.

	["Object-Oriented Analysis and Design with Applications", 2nd
	ed., Grady Booch].

	(1996-12-08)

<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)

1. {application program}.

	2. {function application}.

<standard> Standards are necessary for {interworking},
	{portability}, and {reusability}.  They may be {de facto
	standards} for various communities, or officially recognised
	national or international standards.

	{Andrew Tanenbaum}, in his Computer Networks book, once said,
	"The nice thing about standards is that there are so many of
	them to choose from", a reference to the fact that competing
	standards become a source of confusion, division,
	obsolescence, and duplication of effort instead of an
	enhancement to the usefulness of products.

	Some bodies concerned in one way or another with computing
	standards are {IAB} ({RFC} and {STD}), {ISO}, {ANSI}, {DoD},
	{ECMA}, {IEEE}, {IETF}, {OSF}, {W3C}.

	(1999-07-06)

1. <programming> A property of a programming language where
	created objects and variables continue to exist and retain
	their values between runs of the program.

	2. <hardware> The length of time a phosphor dot on the screen
	of a {cathode ray tube} will remain illuminated after it has
	been energised by the electron beam.  Long-persistence
	phosphors reduce flicker, but generate ghost-like images that
	linger on screen for a fraction of a second.

	(1994-11-09)

<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)

<hardware> To press and release a {button} on a {mouse} or
	other {pointing device}.  This generates an {event}, also
	specifying the screen position, which is processed by the
	{window manager} or {application program}.  On a mouse with
	more than one button, the unqualified term usually implies
	pressing the left-most button (with the right index finger),
	other buttons would be qualified, e.g. "{right-click}".
	{Keyboard} modifiers may also be used, e.g. "shift-click",
	meaning to hold down the shift key on the keyboard while
	clicking the mouse button.

	If the mouse moves while the button is pressed then this is a
	{drag}.

	(1995-03-14)

<programming, mathematics> A {Boolean} {relation}, often an
	equality or {ineqality} relation, between the values of one or
	more mathematical variables (often two).  E.g. x>3 is a
	constraint on x.  {constraint satisfaction} attempts to assign
	values to variables so that all constraints are true.

	{Usenet} newsgroup: {news:comp.constraints}.  {FAQ
	(http://www.cs.unh.edu/ccc/archive/)}.

	(2002-06-08)

1. The portion of a {packet}, preceding the actual data,
	containing source and destination addresses, error checking
	and other fields.

	2. The part of an {electronic mail} message or {news} article
	that precedes the body of a message and contains, among other
	things, the sender's name and e-mail address and the date and
	time the message was sent.

To change a {bit} from whatever state it is in to the other
	state; to change from 1 to 0 or from 0 to 1.  This comes from
	"toggle switches", such as standard light switches, though the
	word "toggle" actually refers to the mechanism that keeps the
	switch in the position to which it is flipped rather than to
	the fact that the switch has two positions.  There are four
	things you can do to a bit: set it (force it to be 1), clear
	(or zero) it, leave it alone, or toggle it.

	[{Jargon File}]

	(1994-12-12)

<operating system> A common {graphical user interface}
	component, consisting of a permanently visible row of button
	{icons} that, when clicked with the {mouse}, cause the program
	to perform some action such as printing the current document
	or changing the {mode} of operation.

	The toolbar buttons often invoke functions accessible via
	{menus} but they are easier to use since they are permanently
	visible.  A typical use would be in a {paint} program where
	the toolbar allows the users to select one of the various
	painting "tools" - brush, pencil, bucket etc.

	Some {application programs} under some {operating systems} may
	allow the user to customise the functions accessible via
	toolbars; in others, the choice is fixed by the programmer.

	(2003-10-24)

1. Not operating.  "The up escalator is down" is considered a
	humorous thing to say, and "The elevator is down" always
	means "The elevator isn't working" and never refers to what
	floor the elevator is on.  With respect to computers, this
	term has passed into the mainstream; the extension to other
	kinds of machine is still hackish.

	2. "go down" To stop functioning; usually said of the
	{system}.  The message from the {console} that every hacker
	hates to hear from the operator is "System going down in 5
	minutes".

	3. "take down", "bring down" To deactivate purposely, usually
	for repair work or {PM}.  "I'm taking the system down to work
	on that bug in the tape drive."  Occasionally one hears the
	word "down" by itself used as a verb in this sense.

	See {crash}; opposite: {up}.

	[{Jargon File}]

	(1994-12-07)

The structure of strings in some language.  A language's
	syntax is described by a {grammar}.  For example, the syntax
	of a binary number could be expressed as

		binary_number = bit [ binary_number ]

		bit = "0" | "1"

	meaning that a binary number is a bit optionally followed by a
	binary number and a bit is a literal zero or one digit.

	The meaning of the language is given by its {semantics}.

	See also {abstract syntax}, {concrete syntax}.

	(1994-10-31)

<operating system> A list from which the user may select an
	operation to be performed.  This is often done with a {mouse}
	or other pointing device under a {graphical user interface}
	but may also be controlled from the keyboard.

	Menus are very convenient for beginners because they show what
	commands are available and make experimentating with a new
	program easy, often reducing the need for user documentation.
	Experienced users however, often prefer keyboard commands,
	especially for frequently user operations, because they are
	faster to use.  In situations such as text entry where the
	keyboard must be used anyway, having to move your hand to the
	mouse to invoke a menu operation is slow.

	There are many different ways of presenting menus but the most
	common are the {menu bar} (with {pull-down menus}) and the
	{context-sensitive menu}.

	The term "menu" tends to be reserved for a list of actions or
	global options, whereas a "{list box}" or other graphical
	{widget} might present any kind of choice.

	See also {menuitis}.

	(1994-12-02)

1. Executable code, especially a "pure code" portion shared
	between multiple instances of a program running in a
	{multitasking} {operating system}.

	Compare {English}.

	2. Textual material in the mainstream sense; data in ordinary
	{ASCII} or {EBCDIC} representation (see {flat ASCII}).  "Those
	are text files; you can review them using the editor."

	These two contradictory senses confuse hackers too.

	[{Jargon File}]

	(1995-03-16)

1. <chat> {Unix}'s simple {talk} command and {protocol}.
	write has been largely superseded by {talk} and then {irc}.

	An enhancement, {RWP}, has been proposed.

	2. <tool> A simple {text editor} for {Windows}.

	(1998-04-28)