Regardless of the technology you are using to read this post, you need to know that its processor was early designed by a trans woman named Sophie Wilson. The ARM microprocessor core is now used in thousands of different products, including smartphones, tablets, gaming consoles and broadband routers. Because of this, the British engineer Sophie Wilson is said to be one of the architects of the modern world.
Over a summer holiday and while she was still a student, Wilson designed and constructed a prototype computer. Her summer project later became the basis for Acorn’s first computer called Acorn System 1, launched in 1979 by the newly established Acorn Computers company. System 1 was cheap and came as a kit that the user would assemble by themself with a manual, but even as its following versions, it was far from being a popular item.
They became well-known after the BBC Broadcaster’s Literacy Program payed Sophie and her co-workers to build the BBC Micro, seeking to bring computers to kids at school in a sort of old-school “One Laptop per Child” project. The BBC Micro was a real success but the processor behind that computer, an 8-bit 6502 that ran at 2MHz, was far from satisfactory. So, in 1983 they decided to build their own CPU.
Some 35 years ago, the Acorn RISC Machine or ARM was built. Steve Furber focused on the hardware architecture and Sophie Wilson designed the instruction set for one of the first RISC processor. The ARM1 was a tiny, low-power, efficient 32-bit CPU with about 25,000 transistors using a 3 micron process. This was truly a milestone in British engineering.
With the 6502 processor the fastest operation was done in two clock cycles (one microsecond). With the ARM1 32-bit operations could be done much quicker. But, the ARM1 didn’t have less instructions than the 6502, it was the complexity on how the instructions were implemented that was reduced.
There wasn’t a unique microprocessor company in the world, there were a number of them producing RISC powered machines and there was a lot of creativity in the market. But everybody was concentrating on high execution throughputs by increasing the complexity of instructions that tended to slow down processors. With high-level design choices and assigning a limited set of simple instructions Sophie made them perform better with less power and at a lower price.
“There were very few of us designing the first ARM so we couldn’t make a complicated processor. Later on I went to design the world’s first small chip. Nowadays everything is built like that.”
The ARM1 was quickly followed by the ARM2 (used to launch Acorn’s Archimedes family of computers), ARM3, ARM6 and so on. ARM became the most successful licensed computer core up to present. Today you can find Cortex-A ARM processors in thousands of different electronics products, powering multiple applications such as industrial equipment, wireless infrastructure, hard disk drives, smart phones, tablets, readers, smart TVs, game consoles and smart appliances. The ARM microprocessor is used in almost everything you hold in your hands nowadays.
“To build something new and complicated, it’s not the sort of quick thing, it’s a sustained effort over a long period of time. It takes many people’s different inputs to make something unique and novel. Overnight success takes 30 years.”
The story of Sophie Wilson, shows us the story of a person that understands tradeoffs, something crucial in software development. She figured out the need to simplify the instruction set, because among other things, they had a small team for designing their chip. Good team work and a keen eye for choosing the right tradeoffs, let her change the CPU world forever.
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- Illustration: Sebastián Navas
- We thank @farbandish for their comments that helped improve this article
- Sophie Wilson interview by Alan Macfarlane (https://www.youtube.com/watch?v=aiSOYnMAxZ4)
- Sophie Wilson — The future of microprocessors. Code Mesh London 2014 (https://www.youtube.com/watch?v=_9mzmvhwMqw)
- ARM creators Sophie Wilson and Steve Furber. Your phone, your tablet — their chip tech (https://www.theregister.co.uk/2012/05/02/unsung_heroes_of_tech_arm_creators_sophie_wilson_and_steve_furber/)
- Wikipedia Profile (https://en.wikipedia.org/wiki/Sophie_Wilson)