Geek's Guide to Britain King’s Parade in Cambridge looks like the last street on earth to have anything to do with computing. On one side is an absurdly ornate college gatehouse in yellow stone and King’s College Chapel, which combines the barn-like shape of a tiny chapel with the scale and detail of a cathedral.
The other side is lined by tall higgledy-piggledy buildings, housing the likes of an old-fashioned sweet shop and a tea room.
Yet King’s Parade is arguably computing’s first street: the concept was invented by a man working in the college behind that gatehouse.
The world’s first general purpose stored-program computer was built a few hundred yards away. A company based in one of those higgledy-piggledy buildings laid the foundations for much of Britain’s IT industry; its greatest rival, the descendent of which has just been sold for £24bn, was based on the square behind.
Cambridge has centuries of history and this tends to obscure the modern bits, making the city’s immense contribution to computing either invisible or hard to spot. This Geek’s Guide walking tour will point out where it all happened, can be completed in under an hour and ends in a pub.
Among the higgledy-piggledy buildings is King’s College Visitor’s Centre, where you can buy an entrance ticket (point 2 on the map linked at the end of this article). Go up King’s Parade, keeping the chapel to your left, pass the grey-stone Senate House then then turn left behind it along Senate House Passage. At its end, turn left down Trinity Lane. You’ll see King’s College Chapel ahead of you, where you show your ticket.
Walk through King’s College Chapel – or spend some time exploring, there’s no IT angle but it is one of the most beautiful buildings on earth – then walk out into the front court (point 3).
In 1931, Alan Turing arrived at King’s College to study mathematics, graduating as one of the top students in his year. In March 1935 he became a college fellow. That summer, lying in Grantchester meadows a few miles south, he dreamed up a “universal machine” to solve a mathematical conundrum in what became his first published paper, On Computable Numbers and the Entscheidungsproblem.
The machine would read, erase and type automatically based on rules set out in a table of behaviour. Turing had created the concept of modern computing.
King's College front court – away from the madding crowd, photo: SA Mathieson
King’s Parade is hardly a mean street, but King’s College is still a haven from it – a bubble within the bubble that is central Cambridge. In 1930s Britain homosexual acts between men were illegal, but King’s didn’t care that Turing was gay: he came out to friends and had several relationships. All in all, he had more fun here than his gloomy image in the likes of The Imitation Game suggests, joining the college rowing club and once downing a pint of beer in one go. Undergraduates turning up for a supervision (Cam-speak for a tutorial) once found his nattily-dressed bear Porgy sitting in front of the fire reading a book: “Porgy is very studious this morning,” said Turing.
Turn right into the back court. Follow the track down its right-hand side then turn left along the river Cam. At the paved path, turn right onto the hump-backed bridge (point 4). From its left-hand side, look at the buildings on the river’s left bank. The door nearest the river is X staircase, where Turing lived and worked.
Skirting the Turing Room - King's College's computing room, for use by student, photo: SA Mathieson
King’s already had links to government codebreaking through classicist Dilly Knox, whose later work would contribute to the Allies’ victory at the Battle of Cape Matapan, off the coast of Greece. Turing decided to return to Britain after taking a doctorate at Princeton and by the summer of 1938 he, too, was involved. He worked on cracking Enigma, the supposedly unbreakable machine used by the Nazis to encode messages, in his room at King’s – locking the outer door to protect national security.
On 3 September 1939, Turing sat in his room with Bob Augenfeld, a young Jewish refugee from Vienna he was helping to support. They heard Neville Chamberlain declare Britain’s entrance into the Second World War. The next day Turing reported to Bletchley Park, Britain’s secret code-breaking centre, where he would help win that war. Porgy the bear and one of Turing’s trophy rowing oars from King’s are now in Bletchley’s museum, as covered in a previous Geek’s Guide.
Walk back towards King’s Parade on the paved path. As you near the manor-house style building between the front and back courts, look at the cellar window nearest the path (point 5): this is the college computer centre, the Turing Room. Hanging on the staircase, which is not open to visitors, is a photograph of Turing.
Leave the college through the absurd gatehouse. Turn right down King’s Parade and look for a section of the building to the right apparently constructed from concrete (actually Portland stone but built in the 1960s). Just before the entrance to King’s Passage, there is a blue plaque 12 feet above the ground remembering Alan Turing (point 6).
Keep walking down King’s Parade, which changes name to Trumpington Street. Look for Silver Street to the right; opposite it turn left along Botolph’s Lane, and its end turn left again up Free School Lane. Passing the Whipple Museum of the History of Science on the right, you get to a stone archway into the New Museums Site (point 7).
When Turing returned to King’s to resume his fellowship in September 1947, the first practical general purpose stored-program electronic computer was under construction a few hundred yards away – but he wasn’t involved.
The Electronic Delay Storage Automatic Calculator (EDSAC) project was led by Maurice Wilkes, who had graduated in the same year as Turing from St John’s College; if Turing had been in charge, EDSAC might have used gin rather than mercury for its ultrasonic delay line memory.
Cuddled by Turing in Cambridge: Porgy, Turing's teddy, photo: SA Mathieson
EDSAC was built over more than two years at Cambridge’s first computer laboratory on the New Museums Site – a place that has seen scientific discoveries including the discovery of DNA and JJ Thomson’s discovery of the electron, commemorated on plaques to the left and right of this gate. EDSAC was built in what had been an anatomy lab, and in the summer staff could smell the formalin which had been used to preserve cadavers and had got into the floorboards. This pioneering computer did its first work on 6 May 1949, working out the squares of the numbers zero to 99.
It carried on for nearly a decade, supporting university staff by doing work previously carried out by teams of “computers”, people with mechanical calculators or tables. It was replaced by EDSAC 2, built by the same team, which worked until 1965. Wilkes’ son Anthony said of his father in 2013: “His objective was not to build a computer but build a computing service, but to build a service he needed a computer.”
EDSAC is another bit of Cambridge computing history that has migrated to Bletchley, where it is being reconstructed at the National Museum of Computing. Another piece of that history has travelled rather further: the world’s first webcam, set up by computer lab staff on this site in 1993 to watch the office’s coffee pot. It was auctioned on eBay in 2001 and acquired by German publisher Der Spiegel for £3,350.
Arup Building: one of Cambridge's hidden locations, under partial wraps, photo: SA Mathieson
The computer lab’s first building was replaced in 1969 by the Arup building on the same site, which was the lab’s home until it moved to the William Gates Building on JJ Thomson Avenue in west Cambridge in 2001. To see the Arup building, including the tower that housed the webcam coffee pot, turn right at the end of Free School Lane on Bene’t Street then right again down Corn Exchange Street’s left-hand side and onto Grand Arcade’s elevated walkway (point 8). The Arup Building is on the other side of the road to the left of the Corn Exchange.
To continue the tour, go back along Benet Street, cross King’s Parade and turn right back towards the tour’s start. Stop opposite number 6 King’s Parade, Inner Space (point 9).
While EDSAC 2 was still calculating, London-based entrepreneur Clive Sinclair started selling a micro-amplifier from the back of a print and design firm at 69 Histon Road in Cambridge. He moved to the city in 1966, when Cambridge-born engineer Chris Curry joined his firm Sinclair Radionics. In 1972 the company launched its first electronic calculator, known for its small size and relatively long battery life, with Curry working on its low power usage.
Sinclair Radionics ran into financial trouble as a result of poor sales of its unreliable digital Black Watch, and the government-owned National Enterprise Board took a large stake. Sinclair, chafing at state control, shifted Curry to a business developing new products such as small, cheap personal computers. In 1977, Curry borrowed £500 from his father for the first month’s rent and some cheap furniture for Science of Cambridge’s office here, at 6a King’s Parade.
With borrowed money and cheap furniture, Sinclair started here at 6a Kings Parade, photo: SA Mathieson
The firm, eventually known as Sinclair Research, launched the MK14 kit computer for £40 in June 1978, which sold in its thousands. Curry felt it could be developed further, but faced with Sinclair’s apparent lack of interest he walked out. Sinclair, rediscovering his interest in computers, left his old company to the National Enterprise Board and moved into King’s Parade. In 1980, he launched the ZX80 computer – apparently named after its Zilog Z80 chip, with an ‘X’ added for extra glamour – and then in March 1981 the ZX81, which cost just £50 as a kit or £70 built.
The ZX81 had a cheap flat keyboard and one kilobyte of RAM: users could buy a 16KB "RAM pack" for an extra £50, although it was also worth investing in some Blu-Tack to stop this falling off and blanking the memory. Despite its limitation, the ZX81 let users program in Basic, do fairly sophisticated mathematics and play games including chess.
In April 1982, Sinclair Research released the ZX Spectrum, with a (slightly) better rubber keyboard and colourful, if clunky, graphics. It cost £125 for a 16KB version and £175 for 48KB, meaning it could run games downloaded from a cassette player. Sales eventually topped five million.
If you ask nicely and take your shoes off, Inner Space may let you see Sinclair’s old offices on the first floor, now a seminar room for studying yoga and meditation.
Continue up King’s Parade, and just before the King’s visitor centre turn right on St Edward’s Passage. When you get to Cambridge’s tourist information centre on Peas Hill, turn left to the market square, then turn right and walk around two of its sides. Between branches of Oasis and Gap there is a narrow alleyway, blocked a few metres in by a wire mesh gate (point 10).
Entrance to 4a Market Hill: birthplace of the Acorn, photo: SA Mathieson
Meanwhile, Chris Curry had teamed up with Hermann Hauser to establish Acorn Computers of 4a Market Hill, behind this gate. The BBC wanted its own brand of computer for a TV series: Sinclair pitched a version of the ZX81, but the quality of the keyboard and the low-resolution graphics counted against it. But Acorn had its own problems, having to build a prototype that fitted the BBC’s spec in five days from a partly-developed design.
Hauser fibbed to both of Acorn’s main developers, Steve Furber and Sophie Wilson, that the other one had agreed to do it. Wilson spent three days building the prototype, debugged it all day Thursday then got a few hours’ sleep before returning at 6am on Friday to write some software.
BBC Acorn team photo, on the steps of 4a Market Hill, photo: SA Mathieson
According to Wilson: “By the time the BBC people arrived at our offices we had an operating system and Basic interpreter running so that we could type on the screen and that stuff could come out. Before they left we had random graphs showing on the screen.”
The effort continued after winning the BBC deal: a team including Wilson spent 29 July 1981, the day of the royal wedding, working on the BBC’s operating system, taking just five minutes off to watch Diana Spencer walk down the aisle. The BBC Micro sold more than 1.5 million and became the default choice for British schools, its decent keyboard giving it a chance of survival when exposed to youthful key-pounding.
This office is also where Elite, a pioneering space exploration game, was commissioned by Acorn’s software division in 1982 from two undergraduates at Jesus College, David Braben and Ian Bell. Launched in September 1984 and working in just 22KB of memory it sold around one million copies.
Continue past the market then take Rose Crescent, which curves around to Trinity Street. Turn right and walk past Trinity and St John’s colleges to Bridge Street. Cross the road, turn left and walk to the Baron of Beef pub (point 11), just beyond its rival the Mitre. Have a drink.
1983 saw Acorn float on the stock market and Sinclair selling stakes to external investors, making Sinclair, Curry and Hauser rich. Sinclair was honoured with a knighthood and moved to a newly-converted office outside the city centre (see Further things to see). But 1984 saw things turning sour. Sinclair launched the QL, an ill-starred business-focused computer.
Acorn suffered disappointing sales of its cut-down £199 Electron and disparaged Sinclair in adverts. Tensions were running high. The crisis broke in the Baron of Beef, when both companies chose the pub for Christmas parties on the same night. Sinclair and Curry got into an argument over Acorn’s advertising which continued in a nearby wine-bar. “He came up behind me and put his hands round my face, his hand went in my eye and it made me see red,” recalled Curry in 2012. “I swung round and swung him a light blow.”
Journalist Michael Jeacock was present and fed the story to the Daily Mirror. The paper published it on Christmas Eve, underneath a picture story of Mirror proprietor Robert Maxwell and magician Paul Daniels headlined: “How to make a £million vanish!”. Daily Express columnist Jean Rook wrote that she found Sir Clive’s fighting spirit sexy. The bust-up featured as the climax of the BBC’s wildly entertaining and intermittently accurate 2009 TV drama about Sinclair and Curry, Micro Men.
Baron of Beef, venue for Sinclair vs. Curry, photo: SA Mathieson
Curry and Sinclair quickly made up, but both companies were on the ropes. In February 1985, Acorn’s shares were suspended and Italy’s Olivetti bought half of the company. This scuppered Sinclair’s plans to float on the stock market and Robert Maxwell came forward with a £12m rescue bid. In August, Maxwell changed his mind – probably for the best, given he was later revealed to have made £millions vanish from his employees’ pension fund.
In 1986 Sinclair Research was bought by Sir Alan Sugar’s Amstrad, a rival computer maker which eventually phased out Sinclair’s products.
Meanwhile, Acorn’s R&D lab on Fulbourn Road on the south-east edge of Cambridge designed the first RISC processor. It was used in 1987’s Acorn Archimedes and the firm developed the technology with Apple. In 1990 the two companies spun off the venture as Advanced RISC Machines, or ARM.
After a brief period in Swaffham Bulbeck, eight miles east of Cambridge, ARM moved back to Fulbourn Road and became the world’s largest chip designer. Over the last quarter of a century, it has licenced more than 1,100 processor designs with more than 300 companies, and those companies have shipped more than 60 billion ARM-based chips, including 95 per cent of smartphones. In July 2016, Japanese conglomerate Softbank offered to pay £24.4bn for the company and at least double ARM’s UK workforce.
Turin's College Boat Trophy: in Bletchley but earned at Cambridge, photo: SA Mathieson
Just eight decades ago, Alan Turing dreamed of a universal machine on a Grantchester meadow. You probably carry such a machine in your pocket, and its electronic heart was probably designed by a company based just three miles east of where Turing lay.
Tour start (point 1 on map): 52.2043, 0.1174
For tour start: CB2 1ST
By train: Regular trains to Cambridge Station, then a walk to the city center or busses from and to Drummer Street bus station.
Coach: Coaches to and from Parkside, a few minutes’ walk south-east from the bus station.
Car: Many roads in central Cambridge are blocked to cars and on-street parking is very limited. Car parking does exist but it’s often easier to use one of Cambridge’s five park and ride locations that charge £1 for up to 18 hours at the park and ride site and £3 return bus fares to the centre.
Most of the tour is on public streets, but King’s College charges £9 for adults and £6 for children, students and senior citizens, although children under 12 visiting with family are free. Cambridge students past and present get in free along with up to two guests with a university card or Camcard while Anglia Ruskin University students can get themselves free access with their cards.
You view the Cambridge walking tour map, here.
Cambrdige University’s Computer Laboratory tour that also includes points of computing and scientific interest here.
Other sites of interest
Sinclair Research’s HQ post 1983, 25 Willis Road, CB1 2AQ. Now Anglia Ruskin University’s Sinclair Building, the site houses a data centre and IT offices. Sinclair had installed an early climate control system using ground water from the building’s own spring – it was originally a water-bottling plant – and a Faraday cage. Sir Clive Sinclair’s large office on the second floor now houses a group of techies. There is a display of Sinclair products and memorabilia in the atrium. Visitors giving prior notice are welcome to visit: email email@example.com.
Cambridge Centre for Computing History, Rene Court, Coldhams Road, CB1 3EW. History of Sinclair, Acorn and other pioneers. It is some way from the city centre on Rene Court, Coldhams Lane so take the Citi 3 bus. Open 10-5pm, Wednesday to Sunday. View the site here. ®