AC2
<audio>
An audio format, succeded by AC3.
Last updated: 2001-12-18
AC3
<audio>
An audio format by Sony[?], the successor of AC2. AC3 is used for multi-channel audio for digital video.
Last updated: 2001-12-18
ACA
Application Control ArchitectureACAP
Application Configuration Access ProtocolAccelerated Graphics Port
(AGP) A bus specification by Intel which gives low-cost 3D graphics cards faster access to main memory on personal computers than the usual PCI bus.
AGP dynamically allocates the PC's normal RAM to store the screen image and to support texture mapping, z-buffering and alpha blending. Intel has built AGP into a chipset for its Pentium II microprocessor. AGP cards are slightly longer than a PCI card. AGP operates at 66 MHz, doubled to 133 MHz, compared with PCI's 33 Mhz. AGP allows for efficient use of frame buffer memory, thereby helping 2D graphics performance as well. AGP provides a coherent memory management design which allows scattered data in system memory to be read in rapid bursts. AGP reduces the overall cost of creating high-end graphics subsystems by using existing system memory. Specification.Last updated: 2004-07-19
accelerator
<hardware>
Additional hardware to perform some function faster than is possible in software running on the normal CPU. Examples include graphics accelerators and floating-point accelerators.
Last updated: 1994-11-08
Accent
<language>
A very high level interpreted language from CaseWare, Inc. with strings and tables. It is strongly typed and has remote function calls.
Last updated: 1994-11-08
accept
Berkeley Unix networking socket library routine to satisfy a connection request from a remote host. A specified socket on the local host (which must be capable of accepting the connection) is connected to the requesting socket on the remote host. The remote socket's socket address is returned.
Unix manual pages: accept(2), connect(2).Last updated: 1994-11-08
Acceptable Use Policy
(AUP) Rules applied by many transit networks which restrict the use to which the network may be put. A well known example is NSFNet which does not allow commercial use. Enforcement of AUPs varies with the network.
Last updated: 1994-11-08
acceptance testing
Formal testing conducted to determine whether a system satisfies its acceptance criteria and thus whether the customer should accept the system.
Last updated: 1996-05-10
Acceptance, Test Or Launch Language
<language>
(ATOLL) The language used for automating the checking and launch of Saturn rockets.
["SLCC ATOLL User's Manual", IBM 70-F11-0001, Huntsville AL Dec 1970].Last updated: 2000-04-03
acceptor
Finite State MachineAccess
<language>
1. An English-like query language used in the Pick operating system.
2. Microsoft Access.
Last updated: 1994-11-08
Access Control List
(ACL) A list of the services available on a server, each with a list of the hosts permitted to use the service.
Last updated: 1994-11-08
access method
1. The way that network devices access the network medium.
2. Software in an SNA processor that controls the flow of data through a network. [physical layer?]Last updated: 1998-03-02
access permission
permissionaccess point
(AP) Any device that acts as a communication hub to allow users of a wireless network to connect to a wired LAN. APs are important for providing heightened wireless security and for extending the physical range of service a wireless user has access to.
Last updated: 2010-03-21
access time
The average time interval between a storage peripheral (usually a disk drive or semiconductor memory) receiving a request to read or write a certain location and returning the value read or completing the write.
Last updated: 1997-06-14
ACCLAIM
<project>
A European Union ESPRIT Basic Research Action.
[What's it about?]Last updated: 1994-11-08
Accounting File
A file which holds records of the resources used by individual jobs. These records are used to regulate, and calculate charges for, resources. An entry is opened in the accounting file as each job begins.
Last updated: 1996-12-08
accounting management
The process of identifying individual and group access to various network resources to ensure proper access capabilities (bandwidth and security) or to properly charge the various individuals and departments. Accounting management is one of five categories of network management defined by ISO for management of OSI networks.
Last updated: 1997-05-05
Account Representative
<job>
A person in a company who identifies new accounts, analyses customer needs, proposes business solutions, negotiates and oversees the implementation of new projects.
Last updated: 2004-03-08
ACCU
Association of C and C++ Usersaccumulator
In a central processing unit, a register in which intermediate results are stored. Without an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory and read them back. Access to main memory is slower than access to the accumulator which usually has direct paths to and from the arithmetic and logic unit (ALU).
The canonical example is summing a list of numbers. The accumulator is set to zero initially, each number in turn is added to the value in the accumulator and only when all numbers have been added is the result written to main memory. Modern CPUs usually have many registers, all or many of which can be used as accumulators. For this reason, the term "accumulator" is somewhat archaic. Use of it as a synonym for "register" is a fairly reliable indication that the user has been around for quite a while and/or that the architecture under discussion is quite old. The term in full is almost never used of microprocessor registers, for example, though symbolic names for arithmetic registers beginning in "A" derive from historical use of the term "accumulator" (and not, actually, from "arithmetic"). Confusingly, though, an "A" register name prefix may also stand for "address", as for example on the Motorola 680x0 family.2. A register, memory location or variable being used for arithmetic or logic (as opposed to addressing or a loop index), especially one being used to accumulate a sum or count of many items. This use is in context of a particular routine or stretch of code. "The FOOBAZ routine uses A3 as an accumulator."
[Jargon File]Last updated: 1999-04-20
accuracy
How close to the real value a measurement is.
Compare precision.Last updated: 1998-04-19
ACE
1. Advanced Computing Environment. 2. Adaptive Communication Environment.ACF
Advanced Communications FunctionACF/NCP
Advanced Communication Function/Network Control ProgramACIA
Asynchronous Communications Interface AdapterACID
A mnemonic for the properties a transaction should have to satisfy the Object Management Group Transaction Service specifications. A transaction should be Atomic, its result should be Consistent, Isolated (independent of other transactions) and Durable (its effect should be permanent).
The Transaction Service specifications which part of the Object Services, an adjunct to the CORBA specifications.Last updated: 1997-05-15
ACIS
<graphics>
Andy, Charles, Ian's System.
A geometric engine that most CAD packages now use. ACIS uses a sophisticated object-oriented approach for modelling, the data is stored in boundary representation. Acis is owned by Spatial Technologies. [How does this differ from "solid modelling"?].Last updated: 1996-03-21
ACK
1. /ak/ The mnemonic for the ACKnowledge character, ASCII code 6.
2. A message transmitted to indicate that some data has been received correctly. Typically, if the sender does not receive the ACK message after some predetermined time, or receives a NAK, the original data will be sent again.
[Jargon File]Last updated: 1997-01-07
ACL
1. Access Control List. 2. Association for Computational Linguistics. 3. A Coroutine Language.ACM
<body>
1. The Association for Computing.
ACME
/ak'mee/ 1. A Company that Makes Everything. The canonical imaginary business. Possibly also derived from the word "acme" meaning "highest point".
2. A program for MS-DOS. [What does it do?]Last updated: 1994-11-08
ACOM
<language>
An early system on the IBM 705.
[Listed in CACM 2(5):16 (May 1959)].Last updated: 1994-11-08
acorn
Acorn Computers Ltd.Acorn Archimedes
ArchimedesAcorn Computer Group
<company>
A holding company for Acorn Computers Limited, Acorn Australia, Acorn New Zealand, Acorn GmbH and Online Media. Acorn Computer Group owns 43% of Advanced RISC Machines Ltd.
Last updated: 1994-11-08
Acorn Computers Ltd.
<company>
A UK computer manufacturer, part of the Acorn Computer Group plc. Acorn was founded on 1978-12-05, on a kitchen table in a back room. Their first creation was an electronic slot machine. After the Acorn System 1, 2 and 3, Acorn launched the first commercial microcomputer - the ATOM in March 1980. In April 1981, Acorn won a contract from the BBC to provide the PROTON. In January 1982 Acorn launched the BBC Microcomputer System. At one time, 70% of microcomputers bought for UK schools were BBC Micros.
The Acorn Computer Group went public on the Unlisted Securities Market in September 1983. In April 1984 Acorn won the Queen's Award for Technology for the BBC Micro and in September 1985 Olivetti took a controlling interest in Acorn. The Master 128 Series computers were launched in January 1986 and the BBC Domesday System in November 1986. In 1983 Acorn began to design the Acorn RISC Machine (ARM), the first low-cost, high volume RISC processor chip (later renamed the Advanced RISC Machine). In June 1987 they launched the Archimedes range - the first 32-bit RISC based microcomputers - which sold for under UKP 1000. In February 1989 the R140 was launched. This was the first Unix workstation under UKP 4000. In May 1989 the A3000 (the new BBC Microcomputer) was launched. In 1990 Acorn formed Advanced RISC Machines Ltd. (ARM) in partnership with Apple Computer, Inc. and VLSI to develop the ARM processor. Acorn has continued to develop RISC based products. With 1992 revenues of 48.2 million pounds, Acorn Computers was the premier supplier of Information Technology products to UK education and had been the leading provider of 32-bit RISC based personal computers since 1987. Acorn finally folded in the late 1990s. Their operating system, RISC OS was further developed by a consortium of suppliers. Usenet newsgroups: comp.sys.acorn, comp.sys.acorn.announce, comp.sys.acorn.tech, comp.binaries.acorn, comp.sources.acorn, comp.sys.acorn.advocacy, comp.sys.acorn.games. Acorn's FTP server. HENSA software archive. Richard Birkby's Acorn page. RiscMan's Acorn page. Acorn On The Net. "The Jungle" by Simon Truss. [Recent history?]Last updated: 2000-09-26
Acorn Online Media
<company>
A company formed in August 1994 by Acorn Computer Group plc to exploit the ARM RISC in television set-top box decoders. They planned to woo British Telecommunications plc to use the box in some of its video on demand trials.
The "STB1" box was based on an ARM8 core with additional circuits to enable MPEG to be decoded in software - possibly dedicated instructions for interpolation, inverse DCT or Huffman table extraction. A prototype featured audio MPEG chips, Acorn's RISC OS operating system and supported Oracle Media Objects and Microword. Online planned to reduce component count by transferring functions from boards into the single RISC chip. The company was origianlly wholly owned by Acorn but was expected to bring in external investment. [Article by [email protected] cross-posted from tandem.news.computergram, 1994-07-07]. In 1996 they releasd the imaginatively titled "Set Top Box 2" (STB20M) with a 32 MHz ARM 7500 and 2 to 32 MB RAM. There was also a "Set Top Box 22". http://www.khantazi.org/Archives/MachineLst.html#STB1. http://www.mcmordie.co.uk/acornhistory/riscpc700.shtml. http://acorn.chriswhy.co.uk/NC.html.Last updated: 2007-11-12
Acorn RISC Machine
The original name of the Advanced RISC Machine.
Last updated: 1995-03-07
A Coroutine Language
<language>
(ACL) A Pascal-based implementation of coroutines.
["Coroutines", C.D. Marlin, LNCS 95, Springer 1980].Last updated: 1994-11-08
ACOS
<language>
A BBS language for PRODOS 8 on Apple II. Macos is a hacked version of ACOS.
Last updated: 1994-11-08
acoustic coupler
A device used to connect a modem to a telephone line via an ordinary handset. The acoustic coupler converts electrical signals from the modem to sound via a loudspeaker, against which the mouthpiece of a telephone handset is placed. The earpiece is placed against a microphone which converts sound to electrical signals which return to the modem. The handset is inserted into a sound-proof box containing the louspeaker and microphone to avoid interference from ambient noise.
Acousitic couplers are now rarely used since most modems have a direct electrical connection to the telephone line. This avoids the signal degradation caused by conversion to and from audio. Direct connection is not always possible, and was actually illegal in the United Kingdom before British Telecom was privatised. BT's predecessor, the General Post Office, did not allow subscribers to connect their own equipment to the telephone line.Last updated: 1994-11-08
ACP
Algebra of Communicating ProcessesACPI
Advanced Configuration and Power InterfaceAcrobat
A product from Adobe Systems, Inc., for manipulating documents stored in Portable Document Format. Acrobat provides a platform-independent means of creating, viewing, and printing documents.
Acropolis: the magazine of Acrobat publishing.Last updated: 1995-04-21
acronym
<jargon>
An identifier formed from some of the letters (often the initials) of a phrase and used as an abbreviation.
A TLA is a meta-acronym, i.e. an acronym about acronyms. This dictionary contains a great many acronyms; see the contents page for a list.Last updated: 2014-08-14
ACSE
Association Control Service ElementACT
<software>
<company>
ACT++
<language>
A concurrent extension of C++ based on actors.
["ACT++: Building a Concurrent C++ With Actors", D.G. Kafura TR89-18, VPI, 1989].Last updated: 1994-11-08
Act1
<language>
An actor language descended from Plasma.
["Concurrent Object Oriented Programming in Act1", H. Lieberman in Object Oriented Concurrent Programming, A. Yonezawa et al eds, MIT Press 1987].Last updated: 1994-11-08
ACT 1
Algebraic Compiler and TranslatorAct2
<language>
An actor language.
["Issues in the Design of Act2", D. Theriault, TR728, MIT AI Lab, June 1983].Last updated: 1994-11-08
Act3
<language>
A high-level actor language by Carl Hewitt. A descendant of Act2 which provides support for automatic generation of customers and for delegation and inheritance.
["Linguistic Support of Receptionists for Shared Resources", C. Hewitt et al in Seminar on Concurrency, S.D. Brookes et al eds, LNCS 197, Springer 1985, pp. 330-359].Last updated: 1994-11-08
Actalk
<language>
A Smalltalk-based actor language developed by J-P Briot in 1989.
["Actalk: A Testbed for Classifying and Designing Actor Languages in the Smalltalk-80 Environment", J-P. Briot, Proc ECOOP '89, pp. 109-129].Last updated: 1994-11-08
Actis
An approach to integrated CASE by Apollo.
Last updated: 1994-11-08
activation record
<compiler>
(Or "data frame", "stack frame") A data structure containing the variables belonging to one particular scope (e.g. a procedure body), as well as links to other activation records.
Activation records are usually created (on the stack) on entry to a block and destroyed on exit. If a procedure or function may be returned as a result, stored in a variable and used in an outer scope then its activation record must be stored in a heap so that its variables still exist when it is used. Variables in the current scope are accessed via the frame pointer which points to the current activation record. Variables in an outer scope are accessed by following chains of links between activation records. There are two kinds of link - the static link and the dynamic link.Last updated: 1995-03-07
active DBMS
<database>
A conventional or passive DBMS combined with a means of event detection and condition monitoring. Event handling is often rule-based, as with an expert system.
Last updated: 1994-11-08
Active Directory
A directory service from Microsoft Corporation, similar in concept to Novell Netware Directory Services, that also integrates with the user organisation's DNS structure and is interoperable with LDAP. Active Directory is included in Windows 2000.
Last updated: 2000-03-28
Active Language I
<tool, mathematics>
An early interactive mathematics system for the XDS 930 at the University of California at Berkeley.
["Active Language I", R. de Vogelaere in Interactive Systems for Experimental Applied Mathematics, A-P 1968].Last updated: 1994-11-08
active matrix display
<hardware>
A type of liquid crystal display where each display element (each pixel) includes an active component such as a transistor to maintain its state between scans.
Contrast passive matrix display.Last updated: 1995-12-09
Active Measurement Project
<networking, tool, project>
(AMP) An NLANR project undertaking site-to-site measurement across the HPC networks. This work is intended to compliment the measurements taken by MCI and Abilene within the networks' infrastructure. Currently round trip times, topology, and packet loss are being measured.
Last updated: 2004-01-18
Active Monitor
A process in an IBM token ring network which ensures a token is present on the ring, removes circulating frames with unknown or invalid destinations, and performs introductions between machines on the ring.
Last updated: 1996-06-18
active object
An object each instance of which has its own thread running as well as its own copies of the object's instance variables.
Last updated: 1998-03-08
Active Reconfiguring Message
<hardware>
(ARM) An efficient mechanism which allows reconfiguration of the hardware logic of a system according to the particular data received or transmitted.
In ARM each message contains extra information in a Reconfiguring Header in addition to the data to be transferred. Upon arrival of the message the Reconfiguring Header is extracted, decoded and used to perform on-the-fly hardware reconfiguration. As soon as the hardware has been reconfigured the data information of the message can be processed. [In what contect is this term used?]Last updated: 1997-06-06
active record pattern
Martin Fowler's name for object relational mapping viewed as a software architecture pattern.
Last updated: 2014-12-03
Active Server Pages
<web, programming>
(ASP) A scripting environment for Microsoft Internet Information Server in which you can combine HTML, scripts and reusable ActiveX server components to create dynamic web pages.
IIS 4.0 includes scripting engines for Microsoft Visual Basic Scripting Edition (VBScript) and Microsoft JScript. ActiveX scripting engines for Perl and REXX are available through third-party developers. [URL?]Last updated: 1999-12-02
ActiveX
A type of COM component that can self-register, also known as an "ActiveX control". All COM objects implement the "IUnknown" interface but an ActiveX control usually also implements some of the standard interfaces for embedding, user interface, methods, properties, events, and persistence.
ActiveX controls were originally called "OLE Controls", and were required to provide all of these interfaces but that requirement was dropped, and the name changed, to make ActiveX controls lean enough to be downloaded as part of a web page. Because ActiveX components can support the OLE embedding interfaces, they can be included in web pages. Because they are COM objects, they can be used from languages such as Visual Basic, Visual C++, Java, VBScript. ["Understanding ActiveX and OLE", David Chappell, MS Press, 1996]. http://microsoft.com/com/tech/activex.asp.Last updated: 2002-04-19
ActiveX Data Objects
<database, Microsoft, programming>
(ADO) Microsoft's library for accessing data sources through OLE DB. Typically it is used to query or modify data stored in a relational database.
Home.Last updated: 2003-07-08
ACT ONE
A specification language.
["An Algebraic Specification Language with Two Levels of Semantics", H. Ehrig et al, Tech U Berlin 83-1983-02-03].Last updated: 1994-11-08
Actor
<language>
An object-oriented language for Microsoft Windows written by Charles Duff of the Whitewater Group ca. 1986. It has Pascal/C-like syntax. Uses a token-threaded interpreter. Early binding is an option.
["Actor Does More than Windows", E.R. Tello, Dr Dobb's J 13(1):114-125 (Jan 1988)].Last updated: 1994-11-08
actor
1. In object-oriented programming, an object which exists as a concurrent process.
2. In Chorus, the unit of resource allocation.
Last updated: 1994-11-08
Actors
<theory>
A model for concurrency by Carl Hewitt. Actors are autonomous and concurrent objects which execute asynchronously. The Actor model provides flexible mechanisms for building parallel and distributed software systems.
http://osl.cs.uiuc.edu/. ["Laws for Communicating Parallel Processes", C. Hewitt et al, IFIP 77, pp. 987-992, N-H 1977]. ["ACTORS: A Model of Concurrent Computation in Distributed Systems", Gul A. Agha <[email protected]>, Cambridge Press, MA, 1986].Last updated: 1999-11-23
actor/singer/waiter/webmaster
<web>
An elaboration of the ages-old concept of the actor/singer/waiter, someone who waits tables for now, but who has aspirations of breaking into the glamorous worlds of acting or New Media or both!
He keeps going to auditions and sending a resumes to C|Net because you have to pay your dues. His credits include being on "Friends" (as an extra), in "ER" (actually, in an ER - he twisted his ankle once; but he counts the x-rays as screen credits), and having been the webmaster of an extensive multimedia interactive website (his hotlist of "Simpsons" links).Last updated: 1998-04-04
Actra
<language>
A multi-processor exemplar-based Smalltalk.
[LaLonde et al, OOPSLA '86].Last updated: 1994-11-08
actual argument
A value, expression, or reference passed to a function or subroutine when it is called and which replaces or is bound to the corresponding formal argument.
See: argument.Last updated: 2002-07-02
actuator/health
/actuator/healthActus
<language>
Pascal with parallel extensions, similar to the earlier Glypnir. It has parallel constants and index sets. Descendants include Parallel Pascal, Vector C and CMU's language PIE.
["A Language for Array and Vector Processors," R.H. Perrott, ACM TOPLAS 1(2):177-195 (Oct 1979)].Last updated: 1994-11-08
Nearby terms:
Abstract Windowing Toolkit ♦ Abstract Window Toolkit ♦ ABSYS ♦ AC2 ♦ AC3 ♦ ACA ♦ ACAP
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