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integrated circuit

(IC, or "chip") A microelectronic semiconductor device consisting of many interconnected transistors and other components. ICs are constructed ("fabricated") on a small rectangle (a "die") cut from a Silicon (or for special applications, Sapphire) wafer. This is known as the "substrate". Different areas of the substrate are "doped" with other elements to make them either "p-type" or "n-type" and polysilicon or aluminium tracks are etched in one to three layers deposited over the surface. The die is then connected into a package using gold wires which are welded to "pads", usually found around the edge of the die.

Integrated circuits can be classified into analogue, digital and hybrid (both analogue and digital on the same chip). Digital integrated circuits can contain anything from one to millions of logic gates - inverters, AND, OR, NAND and NOR gates, flip-flops, multiplexors etc. on a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration.

The first integrated circuits contained only a few transistors. Small Scale Integration (SSI) brought circuits containing transistors numbered in the tens. Later, Medium Scale Integration (MSI) contained hundreds of transistors. Further development lead to Large Scale Integration (LSI) (thousands), and VLSI (hundreds of thousands and beyond). In 1986 the first one megabyte RAM was introduced which contained more than one million transistors.

LSI circuits began to be produced in large quantities around 1970 for computer main memories and pocket calculators. For the first time it became possible to fabricate a CPU or even an entire microprocesor on a single integrated circuit. The most extreme technique is wafer-scale integration which uses whole uncut wafers as components.

[Where and when was the term "chip" introduced?]

Last updated: 1997-07-03

Integrated Database Management System

<database>

(IDMS) A network DBMS written by the staff of B.F.Goorich (Akron, Ohio, USA) circa 1972 and sold to Cullinet (Originally Cullinane, now part of Computer Associates).

IDMS was licensed to ICL in 1976 for porting to, and subsequent development on, their computers. It was implemented on the ICL 1900 Series (DME George 2, George 3, CME, TME), System 4, and ICL 2900 Series (later Series 39 Corporate Servers). The latest version runs on Series 39 OpenVME as IDMSX (IDMS extended).

[Was it a relational database?]

Last updated: 1995-04-19

Integrated Development Environment

Interactive Development Environment

Integrated Drive Electronics

Advanced Technology Attachment

Integrated Information Technology

<company>

(IIT) A Santa Clara based company producing a programmable, single chip H.261 and MPEG system. The chip contains a RISC processor, originally based on the MIPS architecture but now called RISCit, and a "Pixel Processor".

Last updated: 1994-11-03

Integrated Modelling Support Environment

<project>

(IMSE) An Esprit programme.

[Details?]

Last updated: 1999-04-26

Integrated Project Support Environment

<software>

(IPSE) A set of management and technical tools to support software development, usually integrated in a coherent framework, equivalent to a Software Engineering Environment.

Last updated: 1999-04-26

Integrated Services Digital Network

<communications>

(ISDN) A set of communications standards allowing a single wire or optical fibre to carry voice, digital network services and video. ISDN is intended to eventually replace the plain old telephone system.

ISDN was first published as one of the 1984 ITU-T Red Book recommendations. The 1988 Blue Book recommendations added many new features. ISDN uses mostly existing Public Switched Telephone Network (PSTN) switches and wiring, upgraded so that the basic "call" is a 64 kilobits per second, all-digital end-to-end channel. Packet and frame modes are also provided in some places.

There are different kinds of ISDN connection of varying bandwidth (see DS level):

 DS0  =    1 channel  PCM at      64 kbps
 T1  or DS1  =   24 channels PCM at   1.54  Mbps
 T1C or DS1C =   48 channels PCM at   3.15  Mbps
 T2  or DS2  =   96 channels PCM at   6.31  Mbps
 T3  or DS3  =  672 channels PCM at  44.736 Mbps
 T4  or DS4  = 4032 channels PCM at 274.1   Mbps

Each channel here is equivalent to one voice channel. DS0 is the lowest level of the circuit. T1C, T2 and T4 are rarely used, except maybe for T2 over microwave links. For some reason 64 kbps is never called "T0".

A Basic Rate Interface (BRI) is two 64K "bearer" channels and a single "delta" channel ("2B+D"). A Primary Rate Interface (PRI) in North America and Japan consists of 24 channels, usually 23 B + 1 D channel with the same physical interface as T1. Elsewhere the PRI usually has 30 B + 1 D channel and an E1 interface.

A Terminal adapter (TA) can be used to connect ISDN channels to existing interfaces such as EIA-232 and V.35.

Different services may be requested by specifying different values in the "Bearer Capability" field in the call setup message. One ISDN service is "telephony" (i.e. voice), which can be provided using less than the full 64 kbps bandwidth (64 kbps would provide for 8192 eight-bit samples per second) but will require the same special processing or bit diddling as ordinary PSTN calls. Data calls have a Bearer Capability of "64 kbps unrestricted".

ISDN is offered by local telephone companies, but most readily in Australia, France, Japan and Singapore, with the UK somewhat behind and availability in the USA rather spotty.

(In March 1994) ISDN deployment in Germany is quite impressive, although (or perhaps, because) they use a specifically German signalling specification, called 1.TR.6. The French Numeris also uses a non-standard protocol (called VN4; the 4th version), but the popularity of ISDN in France is probably lower than in Germany, given the ludicrous pricing. There is also a specifically-Belgian V1 experimental system. The whole of Europe is now phasing in Euro-ISDN.

See also Frame Relay, Network Termination, SAPI.

FAQ.

Usenet newsgroup: comp.dcom.isdn.

Last updated: 1998-03-29

Integrated Systems Architecture

(ISA for ODP) An Esprit 2 project continuing the ANSA project.

Last updated: 1995-02-21

Integrated Systems Laboratory

<company>

A joint project of Control Data Corporation and NCR Corporation, established in 1973 and dissolved in 1976.

Integrated Systems Laboratory developed Software Writer's Language.

Address: Escondidio, California, USA.

Last updated: 2003-12-31

Nearby terms:

Integer SPECratio ♦ integrated circuit ♦ Integrated Database Management System

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