This week we move to Britain. The industrial revolution started in the Midlands there, and I highly recommend visiting Blists Hills Museum (near Ironbridge which is the first...you'll never guess...iron bridge, from 1779). This is truly the cradle of the industrial revolution. Also, Quarry Bank Mill, near Manchester Airport should you find yourself there with some hours to kill. I was always annoyed in history class when we studied things like Arkwright's Spinning Jenny. Being of a technical bent even then, I wanted to know how it worked. However, the kinds of people who studied history and became history teachers had no interest in that sort of thing and never had a clue. Go to Quarry Bank Mill and you can see the first spinning machines, the first powered looms and the significance of the flying shuttle. The mill pre-dates the steam engine and so was driven by a huge overshot water wheel. Most of the machines are running, making thread and cloth, and you can even treat yourself to a shirt or blouse made there. The weavers loved the first phase of the mechanization of textiles since their problem had always been getting enough thread to weave, since spinning was so time consuming. Once that was mechanized, they could work full time. Even the flying shuttle was good at first, since they could weave cloth that was wider than their arms were long. But it was also the missing link to automating weaving, so the wonderful life of the hand weaver with wide cloth and unlimited thread didn't last for long. But this blog is about semiconductors and electronics, and not just the industrial revolution but some of the roots of computers are in Britain too. Bletchley Park Bletchley park was a secret site during the Second World War for the Government Communications Headquarters (GCHQ) although it had a slightly different name then. It is near the modern town of Milton Keynes, although back then Milton Keynes didn't exist. It was kept secret until the 1970s. I had heard nothing about it studying computer science in the mid-70s. My father told me after she died that one of my great-aunts had actually worked there as some sort of clerk. But after the war, everyone was sworn to secrecy and all the equipment was destroyed, which I think has to count as one of the most insane acts of government vandalism I know of. In fact not just Bletchley Park, but GCHQ itself, remained a secret until 1976 when it was outed in articles in, of all places, Time Out magazine (which was where you would find out what movies and concerts were on in those pre-internet days). The most famous person today who worked at Bletchley Park was Alan Turing. The movies Enigma and The Imitation Game are loosely (and I should emphasize loosely) based on aspects of his life. However, it turns out that several early researchers at British CS departments were also there, although they were not allowed to talk about it, such as Donald Michie in Edinburgh. Donald had a story about going with Turing to bury silver bars in a stream bed, and neither of them could find the same spot after the war. Many of the senior people at GCHQ after its move to Cheltenham were there too. In what I hope is a coincidence, its current building has a similarity to a certain Cupertino company's new headquarters. There are books written on what went on at Bletchley Park. The main focus was decoding communications encrypted with the Enigma machine, which had rotors and a plugboard. It was a very powerful means of encryption but it had one seemingly minor weakness: it never encoded a letter or digit as itself. So if you came across BXZY4R it might have been most things, but one thing it could not have been is BERLIN since then the B would be encoded to B. They also had a complete set of rotors from a captured U-boat (by the British, I might point out, not the Americans as in the Hollywood version!). They have one at Bletchley (see photo below) and if you ever go to a tradeshow where the Cryptography Research division of Rambus is exhibiting, they usually have theirs on display. The first machines used for searching for decrypts were electro-mechanical machines nicknamed "bombes." The picture below shows one of them (rebuilt, the originals were all destroyed). Those things that look like manual dials are actually rotating drums, and each simulates an Enigma rotor. Since it was unknown which rotors were in use in which order on any given day, searching all the rotors at once gave a big increase in performance. Colossus was the next generation. Instead of mechanical switches it used electronics, not transistors of course, they hadn't been discovered, but thermionic valves/tubes. The picture below shows the back of the rebuild of Colossus (with its highly sophisticated cooling mechanism). Although it was still secret until the mid-1970s, when the history books were being written, it is clearly one of the first programmable digital computers. This picture is the front. At the far end of the machine you can see reels which were used to guide paper tape. Since there was no real memory technology beyond using a lot of valves to build a register, there was no way to store the message to be decoded inside the computer. Instead, it was punched onto paper tape and circulated many times. The tape readers ran at 5,000 characters per second (at ten holes per inch, that is over forty feet per second). If you want more details on what actually went on, including quite a bit on the technical details of how the mathematicians and machines did their job, then I recommend Codebreakers: The Inside Story of Bletchley Park , which is an anthology of first person accounts by people who worked there. For more about Alan Turing and his life (and premature death), Andrew Hodge's excellent book The Enigma is the one that brought him to notice by people who have no idea what a Turing machine is, and then TV and movies that have made him more of a household name. Bletchley Park is easy to get to since it is walking distance from Bletchley Station, which less than an hour on the train from London Euston. Bletchley is also just a few minutes from Milton Keynes station, where most of the fast trains to the north stop, so actually the fastest way to get there (from London) is to go to Milton Keynes and get Uber or a taxi. Full details of what to see are on the Bletchley Park website . Babbage's Difference Engine No. 2 One significant British "computer" is not at Bletchley, at least partly because it was never built during the inventor's lifetime. That is Charles Babbage's difference engine. In 1985 The Science Museum—that's actually its name, like the way that what most people call the "British Open" is technically "The Open Championship" since no other country played golf in 1860—decided to build a working Difference Engine No 2 from the original designs dating from the 1840s. The 200th anniversary of Babbage's birth would be in 1991. Two actual scientific questions would be answered. First, could Babbage have built a working machine using the technology of his day. Second, would his original design have worked correctly as designed. The engine was built using modern numerically controlled machining, but care was taken to vary the tolerance to match what Babbage would have had available, and only to use materials he would have had access to. There turned out to be a couple of simple mistakes in the drawings and there was a feeling that they might have been deliberately inserted by Babbage to guard against theft. If you stole the drawings and naively followed them without his understanding, it wouldn't work. The full machine, including the printer, is about 8,000 parts. The engine itself, about 4,000 parts, was completed in time for Babbage's anniversary and the printer a decade later. It weighs 5 tons. It is on view to the public in the Science Museum, which is connected by an underground walkway (what in England is called a subway) to South Kensington tube station (which is what the subway is called in London, confusing I know). According to the embedded data, I took the picture above in April 2007. If you are interested in mechanical computing and also in science fiction, then you should read, if you haven't already, The Difference Engine by William Gibson and Bruce Sterling. The basic premise is that Babbage's difference and analytical engines are real. Computing has arrived in Victorian London using steam-driven mechanical computers. The equivalent of MIPS are miles of gears. If you want to see a real difference engine without leaving the US, then there is a second one. Nathan Myrvhold got the science museum to build one for him by funding the construction of the printer, which was not included in the original reconstruction. It was in the lobby of the Computer History Museum in Mountain View until 2016, but is now in the lobby of Intellectual Ventures Lab in Bellevue WA (Seattle-ish). I was lucky enough to see this one at the CHM when the handle was being turned and it was actually calculating, with the gears all turning. It is an impressive sight. Next Week There is an Enigma machine pictured above. You won't be surprised that you can see one in Germany, where they were developed, along with some earlier version. Those are in the Deutsches Museum in Munich. There are some other surprising gems of computer history there. Sign up for the weekly Breakfast Bytes email:![]()
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