Advanced Audio Coding


(AAC) A successor to MP3, allowing lower bit rates and more stable quality.

See MPEG-2 AAC Low Profile and MPEG-4 AAC Main Profile.

Last updated: 2001-12-02

Advanced Communication Function/Network Control Program


(ACF/NCP, usually called just "NCP") The primary SNA network control program, one of the ACF products. ACF/NCP resides in the communications controller and interfaces with ACF/VTAM in the host processor to control network communications.

NCP can also communicate with multiple hosts using local channel or remote links (PU type 5 or PU type 4) thus enabling cross domain application communication. In a multiple mainframe SNA environment, any terminal or application can access any other application on any host using cross domain logon.

See also Emulator program.

[Communication or Communications?]

Last updated: 1999-01-29

Advanced Communications Function


(ACF) A group of IBM SNA products that provide distributed processing and resource sharing such as VTAM and NCP.

[Communication or Communications?]

Last updated: 1997-05-07

Advanced Computing Environment


(ACE) A consortium to agree on an open architecture based on the MIPS R4000 chip. A computer architecture ARCS will be defined, on which either OS/2 or Open Desktop can be run.

Last updated: 1995-02-03

Advanced Configuration and Power Interface

<hardware, standard>

(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.

Last updated: 1998-03-27

Advanced Data Communications Control Protocol


An ANSI standard bit-oriented data link control protocol.

Last updated: 1997-05-07

Advanced Encryption Standard

<cryptography, algorithm>

(AES) The NIST's replacement for the Data Encryption Standard (DES). The Rijndael /rayn-dahl/ symmetric block cipher, designed by Joan Daemen and Vincent Rijmen, was chosen by a NIST contest to be AES.

AES is Federal Information Processing Standard FIPS-197.

AES currently supports 128, 192 and 256-bit keys and encryption blocks, but may be extended in multiples of 32 bits.

Rijndael home page.

Last updated: 2003-07-04

Advanced Function Presentation

<printer, language>

(AFP) A page description language from IBM introduced in 1984 initially as Advanced Function Printing. AFP was first developed for mainframes and then brought to minicomputers and workstations. It is implemented on the various platforms by Print Services Facility (PSF) software, which generates the native IBM printer language, IPDS and, depending on the version, PostScript and LaserJet PCL as well. IBM calls AFP a "printer architecture" rather than a page description language.

Advanced Function Printing

Advanced Function Presentation

Advanced Intelligent Tape


(AIT) A form of magnetic tape and drive using AME developed by Sony for storing large amounts of data. An AIT can store over 50 gigabytes and transfer data at six megabytes/second (in February 1999). AIT features high speed file access, long head and media life, the ALDC compression algorithm, and a MIC chip.


Last updated: 1999-04-16

Advanced Interactive eXecutive

<operating system>

(AIX) IBM's version of Unix, taken as the basis for the OSF standard.

Usenet newsgroup: comp.sys.unix.aix.

Last updated: 1994-11-24

Advanced Micro Devices, Inc.


(AMD) A US manufacturer of integrated circuits, founded in 1969. AMD was the fifth-largest IC manufacturer in 1995. AMD focuses on the personal and networked computation and communications market. They produce microprocessors, embedded processors and related peripherals, memories, programmable logic devices, circuits for telecommunications and networking applications.

In 1995, AMD had 12000 employees in the USA and elsewhere and manufacturing facilities in Austin, Texas; Aizu-Wakamatsu, Japan; Bangkok, Thailand; Penang, Malaysia; and Singapore.

AMD made the AMD 2900 series of bit-slice TTL components and clones of the Intel 80386 and Intel 486 microprocessors.

AMD Home.

Address: Sunnyvale, CA, USA.

Last updated: 1995-02-27

Advanced Network Systems Architecture


(ANSA) A "software bus" based on a model for distributed systems developed as an ESPRIT project.

Last updated: 1996-04-01

Advanced Peer-to-Peer Networking

<networking, product>

(APPN) IBM data communications support that routes data in a network between two or more APPC systems that need not be adjacent.

Last updated: 1995-02-03

Advanced Power Management


(APM) A feature of some displays, usually but not always, on laptop computers, which turns off power to the display after a preset period of inactivity to conserve electrical power. Monitors with this capability are usually refered to as "green monitors", meaning environmentally friendly.

Not to be confused with a screen blanker which is software that causes the display to go black (by setting every pixel to black) to prevent burn-in.

Last updated: 1997-08-25

Advanced Programmable Interrupt Controller

<integrated circuit>

(APIC) A Programmable Interrupt Controller (PIC) that can handle interrupts from and for multiple CPUs, and, usually, has more available interrupt lines that a typical PIC.

Last updated: 2003-03-18

Advanced Program-to-Program Communications

<networking, product>

(APPC) An implementation of the IBM SNA/SDLC LU6.2 protocol that allows interconnected systems to communicate and share the processing of programs.

Last updated: 1995-02-03

Advanced Research Projects Agency

Defense Advanced Research Projects Agency

Advanced Research Projects Agency Network


(ARPANET) A pioneering longhaul wide area network funded by DARPA (when it was still called "ARPA"?). It became operational in 1968 and served as the basis for early networking research, as well as a central backbone during the development of the Internet. The ARPANET consisted of individual packet switching computers interconnected by leased lines. Protocols used include FTP and telnet. It has now been replaced by NSFnet.

[1968 or 1969?]

Last updated: 1994-11-17

Advanced Revelation


(AREV) A database development environment for personal computers available from Revelation Software since 1982. Originally based on the PICK operating system, there are over one million users worldwide in 1996.

Last updated: 1996-12-12

Advanced RISC Computing Specification

<standard, hardware>

(ARC, previously ARCS) The baseline hardware requirements for an ACE-compatible system.

Last updated: 1995-01-16

Advanced RISC Machine


(ARM, Originally Acorn RISC Machine). A series of low-cost, power-efficient 32-bit RISC microprocessors for embedded control, computing, digital signal processing, games, consumer multimedia and portable applications. It was the first commercial RISC microprocessor (or was the MIPS R2000?) and was licensed for production by Asahi Kasei Microsystems, Cirrus Logic, GEC Plessey Semiconductors, Samsung, Sharp, Texas Instruments and VLSI Technology.

The ARM has a small and highly orthogonal instruction set, as do most RISC processors. Every instruction includes a four-bit code which specifies a condition (of the processor status register) which must be satisfied for the instruction to be executed. Unconditional execution is specified with a condition "true".

Instructions are split into load and store which access memory and arithmetic and logic instructions which work on registers (two source and one destination).

The ARM has 27 registers of which 16 are accessible in any particular processor mode. R15 combines the program counter and processor status byte, the other registers are general purpose except that R14 holds the return address after a subroutine call and R13 is conventionally used as a stack pointer. There are four processor modes: user, interrupt (with a private copy of R13 and R14), fast interrupt (private copies of R8 to R14) and supervisor (private copies of R13 and R14). The ALU includes a 32-bit barrel-shifter allowing, e.g., a single-cycle shift and add.

The first ARM processor, the ARM1 was a prototype which was never released. The ARM2 was originally called the Acorn RISC Machine. It was designed by Acorn Computers Ltd. and used in the original Archimedes, their successor to the BBC Micro and BBC Master series which were based on the eight-bit 6502 microprocessor. It was clocked at 8 MHz giving an average performance of 4 - 4.7 MIPS. Development of the ARM family was then continued by a new company, Advanced RISC Machines Ltd.

The ARM3 added a fully-associative on-chip cache and some support for multiprocessing. This was followed by the ARM600 chip which was an ARM6 processor core with a 4-kilobyte 64-way set-associative cache, an MMU based on the MEMC2 chip, a write buffer (8 words?) and a coprocessor interface.

The ARM7 processor core uses half the power of the ARM6 and takes around half the die size. In a full processor design (ARM700 chip) it should provide 50% to 100% more performance.

In July 1994 VLSI Technology, Inc. released the ARM710 processor chip.

Thumb is an implementation with reduced code size requirements, intended for embedded applications.

An ARM800 chip is also planned.

AT&T, IBM, Panasonic, Apple Coputer, Matsushita and Sanyo either rely on, or manufacture, ARM 32-bit processor chips.

Usenet newsgroup: comp.sys.arm.

Last updated: 1997-08-05

Advanced RISC Machines Ltd.


(ARM) A company formed in 1990 by Acorn Computers Ltd., Apple Computer, Inc. and VLSI Technology to market and develop the Advanced RISC Machine microprocessor family, originally designed by Acorn.

ARM Ltd. also designs and licenses peripheral chips and supplies supporting software and hardware tools. In April 1993, Nippon Investment and Finance, a Daiwa Securities company, became ARM's fourth investor. In May 1994 Samsung became the sixth large company to have a licence to use the ARM processor core.

The success of ARM Ltd. and the strategy to widen the availability of RISC technology has resulted in its chips now being used in a range of products including the Apple Newton. As measured by an independent authority, more ARM processors were shipped than SPARC chips in 1993. ARM has also sold three times more chips than the PowerPC consortium.


Address: Advanced RISC Machines Ltd. Fulbourn Road, Cherry Hinton, Cambridge CB1 4JN, UK.

Telephone: +44 (1223) 400 400. Fax: +44 (1223) 400 410.

Last updated: 1994-11-03

Advanced SCSI Peripheral Interface

<storage, programming>

(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.

Last updated: 1999-03-30

Advanced Software Environment


(ASE) An object-oriented application support system from Nixdorf.

Last updated: 1995-09-12

Advanced STatistical Analysis Program

<tool, electronics>

(ASTAP) A program for analysing electronic circuits and other networks.

["Advanced Statistical Analysis Program (ASTAP) Program Reference Manual", SH-20-1118, IBM, 1973].

Last updated: 2000-01-27

Advanced Technology Attachment

<storage, hardware, standard>

(ATA, AT Attachment or "Integrated Drive Electronics", IDE) A disk drive interface standard based on the IBM PC ISA 16-bit bus but also used on other personal computers. ATA specifies the power and data signal interfaces between the motherboard and the integrated disk controller and drive. The ATA "bus" only supports two devices - master and slave.

ATA drives may in fact use any physical interface the manufacturer desires, so long as an embedded translator is included with the proper ATA interface. ATA "controllers" are actually direct connections to the ISA bus.

Originally called IDE, the ATA interface was invented by Compaq around 1986, and was developed with the help of Western Digital, Imprimis, and then-upstart Conner Peripherals. Efforts to standardise the interface started in 1988; the first draft appeared in March 1989, and a finished version was sent to ANSI group X3T10 (who named it "Advanced Technology Attachment" (ATA)) for ratification in November 1990.

X3T10 later extended ATA to Advanced Technology Attachment Interface with Extensions (ATA-2), followed by ATA-3 and ATA-4.


Last updated: 1998-10-08

Advanced Technology Attachment Interface with Extensions

<storage, standard>

(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").

Last updated: 2000-10-07

Advanced Video Coding


Advanced WavEffect

<multimedia, music, hardware>

(AWE) The kind of synthesis used by the EMU 8000 music synthesizer integrated circuit found on the SB AWE32 card.

Last updated: 1996-12-15

Nearby terms:

Advanced Audio CodingAdvanced Communication Function/Network Control Program

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