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INMOS Ltd. was a British semiconductor company based in Bristol and incorporated in November 1978. The company was founded by Iann Barron, a British computer consultant, Richard Petritz and Paul Schroeder, both American semiconductor industry veterans. Initial funding of £50M was provided by the UK government via the National Enterprise Board. A US subsidiary, INMOS Corporation, was also established in Colorado. Semiconductor fabrication facilities were built in Colorado Springs, Colorado and Newport, Wales.

INMOS's first products were static RAM devices, followed by dynamic RAMs and EEPROMs. Despite early production difficulties, INMOS eventually captured around 60% of the world SRAM market. However, Barron's long-term aim was to produce an innovative microprocessor architecture intended for parallel processing, the transputer. David May and Robert Milne were recruited to design this processor, which eventually went into production in 1985 in the form of the T212 and T414 chips. In the meantime, INMOS had been sold to Thorn-EMI for £95M in September 1984.

The transputer achieved some success as the basis for several parallel supercomputers from companies such as Meiko (formed by ex-INMOS employees in 1985), Floating Point Systems, Parsytec and Parsys. Being a relatively self-contained design, it was also used in some embedded systems. However, the unconventional nature of the transputer and its native occam programming language limited its appeal. During the late 1980s, the transputer (even in its later T800 form) also struggled to keep up with the ever-increasing performance of its competitors.

Other devices produced by INMOS included the A100, A110 and A121 digital signal processors, G364 framebuffer, and a line of video RAMDACs, including the G171, which was adopted by IBM for the original VGA graphics adapter used in the IBM PS/2.

In April 1989, INMOS was sold to SGS-Thomson (now STMicroelectronics). Around the same time, work was started on an enhanced transputer, the T9000. Unfortunately, this encountered various technical problems and delays, and was eventually abandoned, signalling the end of the development of the transputer as a parallel processing platform. However, transputer derivatives such as the ST20 were later incorporated into chipsets for embedded applications such as set-top boxes.

In December 1994, INMOS was fully assimilated into STMicroelectronics, and the INMOS name disappeared from use.

• Arthur Trew and Greg Wilson (eds.) (1991). Past, Present, Parallel: A Survey of Available Parallel Computing Systems. New York: Springer-Verlag. ISBN 0-387-19664-1.
• Mick McClean and Tom Rowland (1986). The Inmos Saga. Quorum Books. ISBN 978-0899301655 .

• INMOS and the transputer: part 1 and part 2 — a talk given by Iann Barron to the Computer Conservation Society of the British Computer Society in 1998
• INMOS ex-employee website