INMOS transputer

The transputer was a series of pioneering microprocessors of the 1980s, featuring integrated memory and serial communication links, intended for parallel computing. It was designed and produced by Inmos, a semiconductor company based in Bristol, United Kingdom.

For some time in the late 1980s, many considered the transputer to be the next great design for the future of computing. While Inmos and the transputer did not ultimately live up to this expectation, the transputer architecture was highly influential in provoking new ideas in computer architecture, several of which have re-emerged in different forms in modern systems.

In the early 1980s, conventional CPUs appeared to reach a performance limit. Up to that time, manufacturing difficulties limited the amount of circuitry designers could place on a chip. Continued improvements in the fabrication process, however, removed this restriction. Soon the problem became that the chips could hold more circuitry than the designers knew how to use. Traditional CISC designs were reaching a performance plateau, and it wasn't clear it could be overcome.

It seemed that the only way forward was to increase the use of parallelism, the use of several CPUs that would work together to solve several tasks at the same time. This depended on the machines in question being able to run several tasks at once, a process known as multitasking. This had generally been too difficult for previous CPU designs to handle, but more recent designs were able to accomplish it effectively. It was clear that in the future this would be a feature of all operating systems.

A side effect of most multitasking design is that it often also allows the processes to be run on physically different CPUs, in which case it is known as multiprocessing. A low-cost CPU built with multiprocessing in mind could allow the speed of a machine to be increased by adding more CPUs, potentially far more cheaply than by using a single faster CPU design.

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