slovodefinícia
interface
(mass)
interface
- rozhranie
interface
(encz)
interface,interface Zdeněk Brož
interface
(encz)
interface,připojení Kenny74
interface
(encz)
interface,rozhraní
interface
(encz)
interface,rozhraní počítače Kenny74
interface
(czen)
interface,interface Zdeněk Brož
interface
(gcide)
interface \interface\ n.
1. a surface forming a common boundary between two things,
especially between two fluids. [WordNet sense 1]
[WordNet 1.5]

2. (Computers) hardware that links one device with another
(especially a computer). [WordNet sense 2]
[WordNet 1.5]

3. (Computers) That part of a computer program which controls
the way a program interacts with a user; the manner of
inputting and outputting of data, and the way information
is presented on a computer monitor; also called {user
interface}; as, a graphical user interface; a
character-based interface.
[PJC]
interface
(wn)
interface
n 1: (chemistry) a surface forming a common boundary between two
things (two objects or liquids or chemical phases)
2: (computer science) a program that controls a display for the
user (usually on a computer monitor) and that allows the user
to interact with the system [syn: interface, {user
interface}]
3: the overlap where two theories or phenomena affect each other
or have links with each other; "the interface between
chemistry and biology"
4: (computer science) computer circuit consisting of the
hardware and associated circuitry that links one device with
another (especially a computer and a hard disk drive or other
peripherals) [syn: interface, port]
interface
(foldoc)
interface

A boundary across which two systems communicate. An
interface might be a hardware connector used to link to other
devices, or it might be a convention used to allow
communication between two software systems. Often there is
some intermediate component between the two systems which
connects their interfaces together. For example, two EIA-232
interfaces connected via a serial cable.

See also graphical user interface, {Application Program
Interface}.

(1996-05-22)
podobné slovodefinícia
command line interface
(msas)
Command Line Interface
- CLI
graphical user interface
(msas)
Graphical User Interface
- GUI
command line interface
(msasasci)
Command Line Interface
- CLI
graphical user interface
(msasasci)
Graphical User Interface
- GUI
command line interface
(encz)
command line interface, n:
egress interface
(encz)
egress interface,výstupní rozhraní [fráz.] [it.] (síťové rozhraní) Ivan
Masár
graphical user interface
(encz)
graphical user interface, n:
inbound interface
(encz)
inbound interface,vstupní rozhraní [fráz.] [it.] (síťové rozhraní) Ivan
Masár
ingress interface
(encz)
ingress interface,vstupní rozhraní [fráz.] [it.] (síťové rozhraní) Ivan
Masár
interfaced
(encz)
interfaced,
interfacer
(encz)
interfacer,
interfaces
(encz)
interfaces,rozhraní n: pl. Zdeněk Brož
musical instrument digital interface
(encz)
musical instrument digital interface, n:
oil-water interface
(encz)
oil-water interface, n:
outbound interface
(encz)
outbound interface,výstupní rozhraní [fráz.] [it.] (síťové
rozhraní) Ivan Masár
parallel interface
(encz)
parallel interface, n:
small computer system interface
(encz)
small computer system interface, n:
user interface
(encz)
user interface,uživatelské rozhraní n: [it.] xo
fiber distributed data interface
(czen)
Fiber Distributed Data Interface,FDDI[zkr.] [voj.] Zdeněk Brož a
automatický překlad
pilot/vehicle interface
(czen)
Pilot/Vehicle Interface,PVI[zkr.] [voj.] Zdeněk Brož a automatický
překlad
scalable coherent interface
(czen)
Scalable Coherent Interface,SCI[zkr.] [voj.] Zdeněk Brož a automatický
překlad
xml user-interface language
(czen)
XML User-interface Language,XUL[it.] [zkr.] mamm
user interface
(gcide)
interface \interface\ n.
1. a surface forming a common boundary between two things,
especially between two fluids. [WordNet sense 1]
[WordNet 1.5]

2. (Computers) hardware that links one device with another
(especially a computer). [WordNet sense 2]
[WordNet 1.5]

3. (Computers) That part of a computer program which controls
the way a program interacts with a user; the manner of
inputting and outputting of data, and the way information
is presented on a computer monitor; also called {user
interface}; as, a graphical user interface; a
character-based interface.
[PJC]
command line interface
(wn)
command line interface
n 1: a user interface in which you type commands instead of
choosing them from a menu or selecting an icon [syn:
command line interface, CLI]
graphical user interface
(wn)
graphical user interface
n 1: a user interface based on graphics (icons and pictures and
menus) instead of text; uses a mouse as well as a keyboard
as an input device [syn: graphical user interface, GUI]
musical instrument digital interface
(wn)
musical instrument digital interface
n 1: a standard protocol for communication between electronic
musical instruments and computers [syn: {musical instrument
digital interface}, MIDI]
oil-water interface
(wn)
oil-water interface
n 1: an interface forming the boundary between the non-miscible
liquids oil and water
parallel interface
(wn)
parallel interface
n 1: an interface between a computer and a printer where the
computer sends multiple bits of information to the printer
simultaneously [syn: parallel interface, parallel port]
small computer system interface
(wn)
small computer system interface
n 1: interface consisting of a standard port between a computer
and its peripherals that is used in some computers [syn:
small computer system interface, SCSI]
user interface
(wn)
user interface
n 1: (computer science) a program that controls a display for
the user (usually on a computer monitor) and that allows
the user to interact with the system [syn: interface,
user interface]
ada semantic interface specification
(foldoc)
Ada Semantic Interface Specification

(ASIS) An intermediate representation for Ada.

E-mail: .

See also Diana.

(1995-02-15)
adaptable user interface
(foldoc)
Adaptable User Interface
Oracle Toolkit

(AUI, Oracle Toolkit) A toolkit from Oracle
allowing applications to be written which will be portable
between different windowing systems. AUI provides one {call
level interface} along with a resource manager and editor
across a range of "standard" GUIs, including Macintosh,
Microsoft Windows and the X Window System.

(1995-03-16)
advanced configuration and power interface
(foldoc)
Advanced Configuration and Power Interface
ACPI

(ACPI) An open industry standard
developed by Intel, Microsoft, and Toshiba for
configuration and power management.

The key element of the standard is power management with two
important improvements. First, it puts the OS in control of
power management. In the currently existing APM model most
of the power management tasks are run by the BIOS, with
limited intervention from the OS. In ACPI, the BIOS is
responsible for the dirty details of communicating with
hardware equipment but the control is in the OS.

The other important feature is bringing power management
features now available only in portable computers to
desktop computers and servers. Extremely low consumption
states, i.e., in which only memory, or not even memory is
powered, but from which ordinary interrupts (real time clock,
keyboard, modem, etc.) can quickly wake the system, are today
available in portables only. The standard should make these
available for a wider range of systems.

For ACPI to work the operating system, the motherboard
chipset, and for some functions even the CPU has to be
designed for it. Microsoft is heavily driving a move toward
ACPI, both Windows NT 5.0 and Windows 98 will support it.
It remains to be seen how much hardware manufacturers will
embrace the technology and whether other operating system
vendors will support it.

ACPI Information Page (http://teleport.com/~acpi/).

(1998-03-27)
advanced scsi peripheral interface
(foldoc)
Advanced SCSI Peripheral Interface
ASPI

(ASPI) A set of libraries designed to
provide programs running under Microsoft Windows with a
consistent interface for accessing SCSI devices. ASPI has
become a de facto standard.

The ASPI layer is a collection of programs (DLLs) that
together implement the ASPI interface. Many problems are
caused by device manufacturers packaging incomplete sets of
these DLLs with their hardware, often with incorrect date
stamps, causing newer versions to get replaced with old.
ASPICHK from Adaptec will check the ASPI components installed
on a computer.

The latest ASPI layer as of March 1999 is 1014.

The ATAPI standard for IDE devices makes them look to the
system like SCSI devices and allows them to work through ASPI.

(http://resource.simplenet.com/primer/aspi.htm).

(1999-03-30)
advanced technology attachment interface with extensions
(foldoc)
Advanced Technology Attachment Interface with Extensions
ATA-2
EIDE
Enhanced IDE
Enhanced Integrated Drive Electronics
Fast ATA
Fast ATA-2

(ATA-2, Enhanced Integrated Drive
Electronics, EIDE) A proposed (May 1996 or earlier?)
standard from X3T10 (document 948D rev 3) which extends
the Advanced Technology Attachment interface while
maintaining compatibility with current IBM PC BIOS
designs.

ATA-2 provides for faster data rates, 32-bit transactions and
(in some drives) DMA. Optional support for power saving
modes and removable devices is also in the standard.

ATA-2 was developed by Western Digital as "Enhanced
Integrated Drive Electronics" (EIDE) around 1994.
Marketroids call it "Fast ATA" or "Fast ATA-2".

ATA-2 was followed by ATA-3 and ATA-4 ("Ultra DMA").

(2000-10-07)
apple attachment unit interface
(foldoc)
Apple Attachment Unit Interface
AAUI

(AAUI) A 14-position, 0.050-inch-spaced
ribbon contact connector. Early Power Macs and Quadras had
an AAUI (Apple Attachment Unit Interface) port (rectangular
shaped) for Ethernet, which requires a transceiver. To
use twisted pair cabling, you would need to get a {twisted
pair} transceiver for the computer with an AAUI port. Some
Power Mac computers had both an AAUI and RJ-45 port; you
can use one or the other, but not both.

The pin-out is:

Pin Signal Name Signal Description
---- -------------- ---------------------------------
1 FN Pwr Power (+12V @ 2.1W or +5V @ 1.9W)
2 DI-A Data In circuit A
3 DI-B Data In circuit B
4 VCC Voltage Common
5 CI-A Control In circuit A
6 CI-B Control In circuit B
7 +5V +5 volts (from host)
8 +5V Secondary +5 volts (from host)
9 DO-A Data Out circuit A
10 DO-B Data Out circuit B
11 VCC Secondary Voltage Common
12 NC Reserved
13 NC Reserved
14 FN Pwr Secondary +12V @ 2.1W or +5V @ 1.9W
Shell Protective Gnd Protective Ground

AAUI signals have the same description, function, and
electrical requirements as the AUI signals of the same name,
as detailed in IEEE 802.3-1990 CSMA/CD Standard, section 7.

(2000-02-10)
application binary interface
(foldoc)
Application Binary Interface
ABI

(ABI) The interface by which an {application
program} gains access to operating system and other
services. It should be possible to run the same compiled
binary applications on any system with the right ABI.

Examples are 88open's Binary Compatibility Standard, the
PowerOpen Environment and Windows sockets.

(1994-11-08)
application program interface
(foldoc)
Application Program Interface
API
Application Programming Interface
Applications Programming Interface

(API, or "application programming interface")
The interface (calling conventions) by which an {application
program} accesses operating system and other services. An
API is defined at source code level and provides a level of
abstraction between the application and the kernel (or
other privileged utilities) to ensure the portability of the
code.

An API can also provide an interface between a {high level
language} and lower level utilities and services which were
written without consideration for the calling conventions
supported by compiled languages. In this case, the API's main
task may be the translation of parameter lists from one format
to another and the interpretation of call-by-value and
call-by-reference arguments in one or both directions.

(1995-02-15)
application programming interface
(foldoc)
Application Program Interface
API
Application Programming Interface
Applications Programming Interface

(API, or "application programming interface")
The interface (calling conventions) by which an {application
program} accesses operating system and other services. An
API is defined at source code level and provides a level of
abstraction between the application and the kernel (or
other privileged utilities) to ensure the portability of the
code.

An API can also provide an interface between a {high level
language} and lower level utilities and services which were
written without consideration for the calling conventions
supported by compiled languages. In this case, the API's main
task may be the translation of parameter lists from one format
to another and the interpretation of call-by-value and
call-by-reference arguments in one or both directions.

(1995-02-15)
applications programming interface
(foldoc)
Application Program Interface
API
Application Programming Interface
Applications Programming Interface

(API, or "application programming interface")
The interface (calling conventions) by which an {application
program} accesses operating system and other services. An
API is defined at source code level and provides a level of
abstraction between the application and the kernel (or
other privileged utilities) to ensure the portability of the
code.

An API can also provide an interface between a {high level
language} and lower level utilities and services which were
written without consideration for the calling conventions
supported by compiled languages. In this case, the API's main
task may be the translation of parameter lists from one format
to another and the interpretation of call-by-value and
call-by-reference arguments in one or both directions.

(1995-02-15)
asynchronous communications interface adapter
(foldoc)
Asynchronous Communications Interface Adapter
ACIA

(ACIA) A kind of {integrated
circuit} that provides data formatting and control to EIA-232
serial interfaces.

[Is this the same as a UART?]

(1997-05-07)
at attachment packet interface
(foldoc)
AT Attachment Packet Interface
ATAPI

(ATAPI) Part of the EIDE interface that provides
additional commands to control a CD-ROM drive or {magnetic
tape}.

[Winn L. Rosch "The Winn L. Rosch Hardware Bible"
(Third Edition), Sams Publishing, 1994].

(1998-11-01)
attachment unit interface
(foldoc)
Attachment Unit Interface

(AUI) The part of the IEEE Ethernet
standard located between the MAC, and the MAU. The AUI
is a transceiver cable that provides a path between a
node's Ethernet interface and the MAU.

(1996-12-08)
basic rate interface
(foldoc)
Basic Rate Interface
2B1D
2B+D
BRI

(BRI, 2B+D, 2B1D) An {Integrated Services
Digital Network} channel consisting of two 64 kbps "bearer"
(B) channels and one 16 kbps "delta" (D) channel, giving a
total data rate of 144 kbps. The B channels are used for
voice or user data, and the D channel is used for control and
signalling and/or X.25 packet networking. BRI is the kind
of ISDN interface most likely to be found in residential
service.

(2002-01-13)
business application programming interface
(foldoc)
Business Application Programming Interface
BAPI

(BAPI) /bap'ee/ A set of
methods provided by an SAP business object.

Release 4.0 of SAP AG's R/3 system supports
object-oriented programming via an interface defined in
terms of objects and methods called BAPIs. For example if
a material object provides a function to check availability,
the corresponding SAP business object type "Material" might
provide a BAPI called "Material.CheckAvailability".

The definitions of SAP business objects and their BAPIs are
kept in an SAP business object repository. SAP provide
classes and libraries to enable a programming team to
build SAP applications that use business objects and BAPIs.
Supported environments include COM and Java.

The {Open BAPI Network
(http://sap.com/solutions/technology/bapis/index.htm)}.
gives background information and lists objects and BAPIs.

(2002-08-30)
calendar application programming interface
(foldoc)
Calendar Application Programming Interface
Calendar API

(CAPI, Calendar API) An API for calendar software.

Microsoft has defined a CAPI for their Schedule+
application.

(1995-01-11)
call-level interface
(foldoc)
Call-Level Interface

(SQL/CLI) A programming interface
designed to support SQL access to databases from
shrink-wrapped application programs.

CLI was originally created by a subcommittee of the {SQL
Access Group} (SAG). The SAG/CLI specification was published
as the Microsoft Open DataBase Connectivity (ODBC)
specification in 1992. In 1993, SAG submitted the CLI to the
ANSI and ISO SQL committees.

SQL/CLI provides an international standard
implementation-independent CLI to access SQL databases.
Client-server tools can easily access databases through
dynamic link libraries. It supports and encourages a rich
set of client-server tools.

SQL/CLI is an addendum to 1992 SQL standard (SQL-92). It was
completed as ISO standard ISO/IEC 9075-3:1995 Information
technology -- Database languages -- SQL -- Part 3: Call-Level
Interface (SQL/CLI). The current SQL/CLI effort is adding
support for SQL3.

(http://jcc.com/sql_cli.html).

(1996-10-27)
command line interface
(foldoc)
command line interface

A means of communication between a
program and its user, based solely on textual input and
output. Commands are input with the help of a keyboard or
similar device and are interpreted and executed by the
program. Results are output as text or graphics to the
terminal.

Command line interfaces usually provide greater flexibility
than graphical user interfaces, at the cost of being harder
for the novice to use. Consequently, some hackers look down
on GUIs as designed For The Rest Of Them.

(1996-01-12)
common gateway interface
(foldoc)
Common Gateway Interface
cgi-bin
CGI program
CGI script

(CGI) A standard for running external
programs from a web HTTP server. CGI
specifies how to pass arguments to the program as part of
the HTTP request. It also defines a set of {environment
variables} that are made available to the program. The
program generates output, typically HTML, which the web
server processes and passes back to the browser.
Alternatively, the program can request URL redirection. CGI
allows the returned output to depend in any arbitrary way on
the request.

The CGI program can, for example, access information in a
database and format the results as HTML. The program can
access any data that a normal application program can, however
the facilities available to CGI programs are usually limited
for security reasons.

Although CGI programs can be compiled programs, they are more
often written in a (semi) interpreted language such as
Perl, or as Unix shell scripts, hence the common name
"CGI script".

Here is a trivial CGI script written in Perl. (It requires
the "CGI" module available from CPAN).

#!/usr/bin/perl
use CGI qw(:standard);

print header, start_html,
h1("CGI Test"),
"Your IP address is: ", remote_host(),
end_html;

When run it produces an HTTP header and then a simple HTML
page containing the IP address or hostname of the machine
that generated the initial request. If run from a command
prompt it outputs:

Content-Type: text/html; charset=ISO-8859-1




Untitled Document



CGI TestYour IP address is: localhost



The CGI program might be saved as the file "test.pl" in the
appropriate directory on a web server,
e.g. "/home/httpd/test".

Accessing the appropriate URL, e.g.
http://acme.com/test/test.pl, would cause the program to
run and a custom page produced and returned.

Early web servers required all CGI programs to be installed in
one directory called cgi-bin but it is better to keep them
with the HTML files to which they relate unless they are truly
global to the site. Similarly, it is neither necessary nor
desirable for all CGI programs to have the extension ".cgi".

Each CGI request is handled by a new process. If the process
fails to terminate for some reason, or if requests are
received faster than the server can respond to them, the
server may become swamped with processes. In order to improve
performance, Netscape devised NSAPI and Microsoft
developed the ISAPI standard which allow CGI-like tasks to
run as part of the main server process, thus avoiding the
overhead of creating a new process to handle each CGI
invocation. Other solutions include mod_perl and FastCGI.

(http://hoohoo.ncsa.uiuc.edu/cgi).

(2007-05-22)
common isdn application programming interface
(foldoc)
Common ISDN Application Programming Interface
Common-ISDN-API

(CAPI, Common-ISDN-API) A programming interface
standard for an application program to communicate with an
ISDN card.

Work on CAPI began in 1989, focussing on the German ISDN
protocol, and was finished in 1990 by a CAPI working group
consisting of application providers, ISDN equipment
manufacturers, large customers, user groups and DBP Telekom,
resulting in COMMON-ISDN-API Version 1.1. Following
completion of the international protocol specification, almost
every telecommunication provider offers BRI and PRI with
protocols based on Q.931 / ETS 3009 102. Common-ISDN-API
Version 2.0 was developed to support all Q.931 protocols.

(http://capi.org/).

[Why not CIAPI?]

(1998-09-07)
common program interface
(foldoc)
Common Program Interface
CPI

(CPI) The API of SAA.

(1997-12-01)
copper distributed data interface
(foldoc)
Copper Distributed Data Interface
CDDI

(CDDI) FDDI running over conventional copper cables.
A Cisco/Crescendo copyright term(?). All FDDI connections,
single-attached or dual-attached, can be either optical fibre
or copper.

(1994-12-14)
data link provider interface
(foldoc)
Data Link Provider Interface
DLPI

(DLPI) The interface that a network driver
presents to the (higher level) logical link layer for
driving the network at the datagram level in a Unix
STREAMS environment and possibly elsewhere.

DLPI corresponds to ISO 8802/2 (LLC) which covers both
connection-oriented and connectionless protocols.

[Is this correct? Better explanation?]

(1996-01-29)
data over cable service interface specification
(foldoc)
Data Over Cable Service Interface Specification
Data Over Cable Systems Interface Specifications
DOCSIS

(DOCSIS) ITU-approved interface
requirements for cable modems involved in high-speed data
distribution over a cable television network. DOCSIS
compatible equipment uses a 6 MHz carrier band for
downstream, using 64 and 256 QAM (ITU Annex B), and QPSK
and 16 QAM for upstream, allowing up to 36 and 10 Mb/s,
respectively for downstream and upstream channels.

CableLabs FAQ (http://cablemodem.com/FAQs.html).

(2001-07-10)
data over cable systems interface specifications
(foldoc)
Data Over Cable Service Interface Specification
Data Over Cable Systems Interface Specifications
DOCSIS

(DOCSIS) ITU-approved interface
requirements for cable modems involved in high-speed data
distribution over a cable television network. DOCSIS
compatible equipment uses a 6 MHz carrier band for
downstream, using 64 and 256 QAM (ITU Annex B), and QPSK
and 16 QAM for upstream, allowing up to 36 and 10 Mb/s,
respectively for downstream and upstream channels.

CableLabs FAQ (http://cablemodem.com/FAQs.html).

(2001-07-10)
desktop management interface
(foldoc)
Desktop Management Interface
DMI

(DMI) A specification from the
Desktop Management Task Force (DMTF) that establishes a
standard framework for managing networked computers. DMI
covers hardware and software, desktop systems and
servers, and defines a model for filtering events and
describing interfaces.

DMI provides a common path for technical support, IT managers,
and individual users to access information about all aspects
of a computer - including processor type, installation date,
attached printers and other peripherals, power sources,
and maintenance history. It provides a common format for
describing products to aid vendors, systems integrators, and
end users in enterprise desktop management.

DMI is not tied to any specific hardware, operating system, or
management protocols. It is easy for vendors to adopt,
mappable to existing management protocols such as {Simple
Network Management Protocol} (SNMP), and can be used on
non-network computers.

DMI's four components are:

Management Information Format (MIF) - a text file containing
information about the hardware and software on a computer.
Manufacturers can create their own MIFs specific to a
component.

Service layer - an OS add-on that connects the management
interface and the component interface and allows management
and component software to access MIF files. The service layer
also includes a common interface called the local agent, which
is used to manage individual components.

Component interface (CI) - an application program interface
(API) that sends status information to the appropriate MIF
file via the service layer. Commands include Get, Set, and
Event.

Management interface (MI) - the management software's
interface to the service layer. Commands are Get, Set, and
List.

CI, MI, and service layer drivers are available on the
Internet. Intel's LANDesk Client Manager (LDCM) is based
on DMI.

Version: 2.0s (as of 2000-01-19).

(http://dmtf.org/spec/dmis.html).

{Sun overview

(http://sun.com/solstice/products/ent.agents/presentations/sld014.html)}.

(2000-01-19)
dos protected mode interface
(foldoc)
DOS Protected Mode Interface
DPMI

(DPMI) The method which Microsoft prescribes for a DOS
program to access extended memory under a multitasking
environment, e.g. Microsoft Windows. This service is
provided by the HIMEM.SYS driver on IBM PCs.

The DPMI specification was finalized in 1990. The
specification itself is available from {Intel Literature
Sales}.

VCPI (Virtual Control Program Interface), which was an
alternative, and incompatible method for doing the same thing.

["Windows 3.1 Secrets", Brian Livingston, 1992, ISBN
1-878058-43-6, pages 280-281 and 302].

(1995-01-12)
enhanced small disk interface
(foldoc)
Enhanced Small Disk Interface
ESDI

(ESDI) An obsolete hard disk
controller standard, first introduced by Maxtor in 1983,
and intended to be the successor to the original
ST-506/ST-412. ESDI was faster and more reliable, but
still could not compete with IDE and SCSI.

EDSI used two cables: a 20-pin data cable to each drive and a
single 34-pin control cable daisy chain with the controller
at one end and a terminator at the other. In PCs, it
supported up to two drives at 1-2MB/s with drives up to 2GB.

{PC Guide
(http://pcguide.com/ref/hdd/if/obsoESDI-c.html)}.

(2003-08-01)
extensible firmware interface
(foldoc)
Extensible Firmware Interface
EFI

(EFI) A specification originating from {Intel
Corporation}, defining the interface between an {operating
system} and platform firmware, and aiming to reduce OS
dependence on details of the firmware implementation.

EFI Home (http://intel.com/technology/efi/).

(2004-10-23)
external machine interface
(foldoc)
External Machine Interface
EMI

(EMI) A protocol primarily used to connect to
short message service centres for mobile telephones. EMI
is an extension to Universal Computer Protocol (UCP). EMI was
was developed by CMG, now a part of LogicaCMG, the current
SMSC market leader.

Each byte of the message is encoded as two hexadecimal
characters using an encoding not quite like ASCII.

{EMI specification
(http://www.netfunitalia.it/downloads/SMSC_EMI_Specification.PDF)}

(2007-09-10)
fiber distributed data interface
(foldoc)
Fiber Distributed Data Interface
FDDI

(FDDI) A 100 Mbit/s ANSI standard local area network
architecture, defined in X3T9.5. The underlying medium is
optical fibre (though it can be copper cable, in which case
it may be called CDDI) and the topology is a
dual-attached, counter-rotating token ring.

FDDI rings are normally constructed in the form of a "dual
ring of trees". A small number of devices, typically
infrastructure devices such as routers and concentrators
rather than host computers, are connected to both rings -
these are referred to as "dual-attached". Host computers
are then connected as single-attached devices to the
routers or concentrators. The dual ring in its most
degenerate form is simply collapsed into a single device. In
any case, the whole dual ring is typically contained within a
computer room.

This network topology is required because the dual ring
actually passes through each connected device and requires
each such device to remain continuously operational (the
standard actually allows for optical bypasses but these are
considered to be unreliable and error-prone). Devices such as
workstations and minicomputers that may not be under the
control of the network managers are not suitable for
connection to the dual ring.

As an alternative to a dual-attached connection, the same
degree of resilience is available to a workstation through a
dual-homed connection which is made simultaneously to two
separate devices in the same FDDI ring. One of the
connections becomes active while the other one is
automatically blocked. If the first connection fails, the
backup link takes over with no perceptible delay.

Usenet newsgroup: news:comp.dcom.lans.fddi.

(1994-12-13)