David May (computer scientist)
Lead architect of the transputer and founder of XMOS Semiconductor.
David May (born 1951) is a British computer scientist whose work spans computer architecture, parallel computing, and robotics. He is a professor in the Department of Computer Science at the University of Bristol and founded XMOS Semiconductor, acting as its chief technology officer until February 2014. May led the design of the transputer, the first microprocessor built for parallel and distributed computing. He is among a small group of people to have overseen the creation of a CPU architecture, an interconnect, and a modern programming language.
May was born in Holmfirth, Yorkshire, and attended Queen Elizabeth Grammar School in Wakefield. From 1969 to 1972, he studied at King’s College, Cambridge, first mathematics and then computer science at the University of Cambridge Mathematical Laboratory (now the Computer Laboratory). There, he learned computer architecture from David Wheeler, who worked on EDSAC and pioneered subroutines, and compiler writing from Martin Richards, who developed BCPL, the language that laid the groundwork for C.
After moving to the University of Warwick, May began research in robotics. The difficulty of building sensing and control systems led him to create an early concurrent programming language, EPL, which ran on a cluster of single-board microcomputers linked by serial connections. This work connected him with Tony Hoare and Iann Barron, a founder of Inmos. In 1995, May became Head of Computer Science at the University of Bristol, where he introduced degree programmes with entrepreneurial elements that spawned multiple student start-ups and helped establish the Bristol Robotics Laboratory. He held the post until 2005, when he co-founded XMOS and became its CTO. He remains a professor at Bristol, focusing on computer architecture and programming languages for robotics, the internet of things, and edge computing.
Inmos was founded in 1978 with a £50 million UK government investment. May joined to work on microcomputer architecture and became the lead architect of the transputer, which has been used in over a billion units worldwide for applications including massively parallel supercomputing, digital image processing, high-energy physics, robotics, and military systems. Alongside the transputer, May designed the Occam programming language, extending his earlier work and influenced by Tony Hoare’s CSP.
Quick Facts
- Honorific Prefix
- Professor
- Workplaces
- University of Bristol
- Education
- University of Cambridge
- Thesis Title
- <!--(or
- Known For
- Parallel computing / Processor design / Transputer / Occam / Formal Methods
- Awards
- FRS (1991) / FREng (2010) / Patterson Medal (1992)
Facts from the source article.
Lore & Background
May studied at King's College, Cambridge, first Mathematics then Computer Science, learning computer architecture from David Wheeler and compiler writing from Martin Richards. He moved to the University of Warwick for robotics research, where he designed an early concurrent programming language, EPL, running on a cluster of single-board microcomputers. This work brought him into contact with Tony Hoare and Iann Barron, leading to his involvement with Inmos, formed in 1978 with a £50m UK government investment. At Inmos, May became lead architect of the transputer and designed the associated programming language Occam, influenced by Hoare's CSP. He introduced formal verification techniques into the design of the T800 floating point unit and the T9000 transputer, some of the earliest uses of formal verification in microprocessor design. May also initiated the design of one of the first VLSI packet switches, the C104. In 1995, he became Head of the Computer Science Department at the University of Bristol, introducing degree programmes with entrepreneurial activity and helping set up the Bristol Robotics Laboratory. He held that post until 2005, when he co-founded XMOS Semiconductor, serving as CTO until 2014.
Reader's Guide
May's significance lies in his pioneering contributions to parallel computing and formal methods in microprocessor design. The transputer, which he led architecting, was the first microprocessor designed for parallel and distributed computing, used in over 1 billion units worldwide across supercomputing, image processing, scientific computing, robotics, and military applications. His design of the Occam programming language extended his earlier work and was influenced by Tony Hoare. The formal verification techniques he introduced with Hoare and the Oxford Programming Research Group, involving specifications, correctness preserving transformations, and model checking, gave rise to the initial version of the FDR checker. May's work on communication and networking is particularly influential: the standard IEEE 1355 derives from the transputer's network interface and underpins SpaceWire, a spacecraft communication network used by NASA and ESA, including the James Webb Space Telescope. His law, May's Law, states that software efficiency halves every 18 months, compensating Moore's Law. As of 2026, he holds 54 patents in microprocessors, multi-processing, and communication protocols.
Did You Know?
- The transputer processor has been used in over 1 billion units worldwide.
- May's work on the transputer's network interface led to the IEEE 1355 standard, which underpins SpaceWire used by NASA and ESA.
- May wrote the original instruction set for Picochip, later acquired by Mindspeed Technologies and then Intel.
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