1985 · First RISC Chip Running · Work 918 of 1,871
A development laboratory in Cambridge in England on an April afternoon, on a bench a cream home computer with plain, smooth, unmarked black keys, a grey ribbon cable to an open metal box, inside it a green board with a flat square lilac-grey ceramic chip three centimetres across, gold contact teeth along all four edges, a small monitor turned away from the lens glowing softly, two slender hands in the pushed-up sleeves of a grey knitted jumper resting on the keys, a second pair of hands easing the cork from a dark green bottle with a plain gold foil neck, white plastic cups, daylight through a tall window.
Who
Sophie Wilson (born 1957) is a British computer scientist and one of the two minds behind the ARM processor. Born in Leeds, she began studying computer science at Cambridge in 1975. For the young firm Acorn Computers she designed the Acorn System 1, a small computer sold from 1979. With Steve Furber she built the prototype of the BBC Micro in less than a week; she wrote its operating system and BBC BASIC. More than a million were sold, many of them to British schools. She then designed the instruction set of the ARM, a lean 32-bit processor built on the RISC principle. Today the ARM architecture sits in most smartphones. Later she designed the FirePath processor and developed it further at Broadcom. She is a Fellow of the Computer History Museum (2012) and of the Royal Society (2013); in 2022 she shared the Draper Prize with Furber, David Patterson and John Hennessy. Sophie Wilson is a trans woman. Museums and learned societies credit all of her work under her present name, and so does this text.
The moment
On 26 April 1985 the first ARM chips came back to Cambridge from the manufacturer VLSI Technology, at 1 pm as Steve Furber remembers it. Each carried just under 25,000 transistors. The team plugged a chip into the second processor board that stood ready; it was attached to a BBC Micro, which handled all input and output over the link Wilson had designed, the "Tube". The operating system booted, BBC BASIC ran. Wilson recalls that they typed "PRINT PI" and cracked open the bottles of champagne, because everything worked. Furber gives 3 pm and remembers the first greeting on the screen as "Hello World, I am ARM". The chip even ran before its own power supply was connected, drawing enough current from the interface. The picture shows that afternoon: hands on the keyboard, the lilac-grey chip in the open case, and above them a cork just leaving the bottle.
The other side
The success came in the middle of a crisis. Acorn had lost about 11 million pounds in the six months to January 1985; on 20 February 1985, two months before the first run, Olivetti bought 49 per cent of the company for about 12 million pounds. That the ARM needed so little power was, in Wilson's own words, not intended but an accident; later it proved fundamental to small devices. In 2012 she spoke of more than 32 billion ARM cores shipped. To have 20 billion copies of a little bit of her brain running around the world, she said, is scary at times.
What the sources leave open: No photograph of 26 April 1985 is known, and there is no public-domain picture of Sophie Wilson, so the work shows only hands. Room, clothing and bottles are not recorded. Wilson recalls "PRINT PI" (the CHM transcript reads "PRINT PIT"), Furber "Hello World, I am ARM"; which line appeared on the screen first is unclear, so it is turned away. Older sources list her under an earlier first name; the work does not use it.