See also {complete graph}, {complete inference system},
	{complete lattice}, {complete metric space}, {complete partial
	ordering}, {complete theory}.

	[1. or 2. or both?]

	(1996-04-24)

1. <messaging> {Short Message Service}.

	2. <storage> {Storage Management Services}.

	3. <operating system> {System Management Server}.

	(1999-05-02)

<communications> (GSM, originally "Groupe de travail Sp?ciale
	pour les services Mobiles") One of the major {standards} for
	digital {cellular} communications, in use in over 60 countries
	and serving over one billion subscribers.  The GSM standard is
	currently used in the 900 MHz, 1800 MHz and 1900 MHz bands.

	{GPRS} allows {circuit switched} data communications over GSM,
	and is widely used for {World Wide Web} and {electronic mail}
	access from cellular devices.

	{GSM World (http://www.gsmworld.com/)}.

	(2005-01-26)

<hardware, communications> (Modulator/demodulator) An
	electronic device for converting between serial data
	(typically {EIA-232}) from a computer and an audio signal
	suitable for transmission over a telephone line connected to
	another modem.  In one scheme the audio signal is composed of
	silence (no data) or one of two frequencies representing zero
	and one.

	Modems are distinguished primarily by the maximum data rate
	they support.  Data rates can range from 75 bits per second up
	to 56000 and beyond.  Data from the user (i.e. flowing from
	the local terminal or computer via the modem to the telephone
	line) is sometimes at a lower rate than the other direction,
	on the assumption that the user cannot type more than a few
	characters per second.

	Various data {compression} and error correction {algorithms}
	are required to support the highest speeds.  Other optional
	features are {auto-dial} (auto-call) and {auto-answer} which
	allow the computer to initiate and accept calls without human
	intervention.  Most modern modems support a number of
	different {protocols}, and two modems, when first connected,
	will automatically negotiate to find a common protocol (this
	process may be audible through the modem or computer's
	loudspeakers).  Some modem protocols allow the two modems to
	renegotiate ("retrain") if the initial choice of data rate is
	too high and gives too many transmission errors.

	A modem may either be internal (connected to the computer's
	{bus}) or external ("stand-alone", connected to one of the
	computer's {serial ports}).  The actual speed of transmission
	in characters per second depends not just the modem-to-modem
	data rate, but also on the speed with which the processor can
	transfer data to and from the modem, the kind of compression
	used and whether the data is compressed by the processor or
	the modem, the amount of noise on the telephone line (which
	causes retransmissions), the serial character format
	(typically {8N1}: one {start bit}, eight data bits, no
	{parity}, one {stop bit}).

	See also {acoustic coupler}, {adaptive answering}, {baud
	barf}, {Bulletin Board System}, {Caller ID}, {SoftModem},
	{U.S. Robotics}, {UUCP}, {whalesong}.

	{Usenet} newsgroup: {news:comp.dcom.modems}.

	(2002-05-04)

<data> To read data that is not in the native format of the
	application.  For example, a {web browser} will have its own
	way of storing {bookmarks} but it will usually provide a
	function to import bookmarks from {Internet Explorer}.  The
	alternative is to provide an independent external conversion
	utility but this is usually less convenient for the user.

	(2004-11-15)

<file system> An element of data storage in a {file system}.

	The history of computing is rich in varied kinds of files and
	{file systems}, whether ornate (e.g., {Macintosh file system}
	for a well-known case) or deficient (e.g., many simple
	pre-1980s file systems don't allow {directories}).

	However, the prototypical file has these characteristics:

	* It is a single sequence of bytes (but consider {Macintosh}
	{resource forks}).

	* It has a finite length, unlike, e.g. a {Unix} {device}.

	* It is stored in a {non-volatile storage} medium (but see
	{ramdrive}).

	* It exists (nominally) in a {directory}.

	* It has a name that it can be referred to by in file
	operations, possibly in combination with its {path}.

	Additionally, a file system may associate other information
	with a file, such as {permission} bits or other {file
	attributes}; timestamps for file creation, last revision, and
	last access; revision numbers (a` la VMS), and other kinds of
	{magic}.

	Compare: {document}.

	(1997-04-08)

<language, programming> (Or "source", or rarely "source
	language") The form in which a computer program is written by
	the programmer.  Source code is written in some formal
	programming language which can be compiled automatically into
	{object code} or {machine code} or executed by an
	{interpreter}.

	(1995-01-05)

<operating system> A {directory} in the sense of a collection
	of computer {files}.  The term is more common in systems such
	as the {Macintosh} or {Windows 95} which have a {graphical
	user interface} and provide a graphical {file browser} in
	which directories are traditionally depicted as folders (like
	small briefcases).

	(1997-03-20)

1. <operating system> (Or "erase") To make a file
	inaccessible.

	Usually this operation only deletes information from the
	tables the {file system} uses to locate named files; the
	file's contents still exist on {disk} and can sometimes be
	recovered by scanning the whole disk for strings which are
	known to have been in the file.  Files created subsequently on
	the same disk are quite likely to reuse the same blocks and
	thus overwrite the deleted file's data permanently.

	2. <character> The {control character} with {ASCII} code 127.
	Usually entering this character from the keyboard deletes the
	last character typed from the {input buffer}.  Sadly there is
	great confusion between {operating systems} and keyboard
	manufacturers as to whether this function should be assigned
	to the delete or {backspace} key/character.

	The choice of code 127 (binary 1111111) is not arbitrary but
	dates back to the use of {paper tape} for input.  The delete
	key rewound the tape by one character and punched out all
	seven holes, thus obliterating whatever character was there
	before.  The tape reading software ignored any delete
	characters in the input.

	(1996-12-01)