| | | | Resistors, capacitors, diodes and transistors forming a circuit on a wafer of semiconducting material, typically a crystal of silicon. Performing a wide range of functions, they are also know as ICs, silicon chips, computer chips, microchips or just chips. The circuitry is normally sealed within a plastic case with leads/connectors coming out from it, to handle signals in and out and the power supply required. There may be anything up to several million circuits within a few square millimetres on the chip. ICs can be linear or digital. Linear chips are analogue in that they can have a continuously variable (linear) output depending on the input. Computers use digital ICs (other than perhaps in attached peripherals such as tuners and amplifiers) which operate at only a few pre-defined states on the binary principal of 1 or 0, "on" or "off". The roots of the integrated circuit go back to the start of the 20th century, but it was not put into a configuration useable in every day applications until the 1960's after it's light weight and reduced size, when compared with discrete traditional components, meant it became attractive to the US space and missile programs resulting in a huge injection of develpment funding. The other key advantage of ICs over having separate individual transistors and capacitors etc is cost - it is far cheaper to "print" the circuits on an IC than it is to manufacture the thousands or millions of separate parts that would be required to produce the same device. There have been several distinct generations in the evolution of the integrated circuit: Small Scale Integration (SSI) - using a few dozen transistors, Medium Scale Integration (MSI) - in which the transistors ran into the hundreds and Large Scale Integration - where they numbered tens of thousands, had all occurred by the 1970s. Next came Very Large Scale Integration (VLSI) which continues, with current processor chips containing many billions of transistors. There is little sign of things slowing down as manufacturing processes and design software contine to improve. | | | |
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