The Man Who Invented the Computer

by Jane Smiley

  It was Tommy Flowers who conceived and built Colossus at Dollis Hill, where he had worked since 1926. Even though because of his prewar vacuum-tube experiment Flowers knew how much faster the tubes were at such work, in 1943 he could not at first persuade the authorities at Bletchley Park to try the new technology. He decided to construct a prototype on his own, commandeering a post office factory in Birmingham to make the parts. He had a sixteen-hundred-tube processor by the end of 1943 but saw immediately that though it worked, it was not fast enough, and he began on an improved version in February 1944. He was told that the machine had to be installed at Bletchley and functioning by the first of June, the planned date for the invasion of Normandy by the Allied forces. He succeeded. According to Jack Copeland, “Despite the fact that no such machine had previously been attempted, the computer was in working order almost straight away and ready to begin its fast-paced attack on the German messages.” Not long before he died, Flowers did write enough about the history, the purpose, and the features of Colossus so that we may understand its main features:

  Colossus was a special-purpose machine designed primarily to perform processes devised by Bletchley Park for discovering the settings of the code wheels made by the [German] machine operators before the messages were sent. Much of the Colossus was an electronic analogue of the Lorenz Tunny machine. Bletchley Park also eventually found ways of using the machine to discover the Tunny wheel patterns when they were routinely changed. (Colossus did not itself decode intercepted messages. This was done by other machines, specially modified teleprinters, also known as Tunny machines.)

  The Colossus operated on two data streams simultaneously—one was the strip of paper from the teleprinter, carrying the message, and the other was a data stream that mimicked various wheel combinations that a Lorenz machine would use. The strip of paper carrying the hole pattern that was the message was made into a loop, then the loop was passed over and over through a photoelectric reader that registered hole or no—each recognition registered as an electric impulse to the logic unit (the “processor”—the part of the machine that eventually would be made up of 2,400 vacuum tubes). Each pass of the loop through the scanner included a blank section that defined the beginning and the end of the message. The tape passed through the scanner over and over “until every possible combination of digits” that appeared at the beginning of the message had been read—once the beginning of the message had been worked out, the rest of the message could be decoded. The electric impulses that passed through the holes in the tape registered on a counter; the code breakers soon discovered that a scan that did not reveal a message always contained fewer impulses than a scan that revealed a message—that is, the word “colossus” contains eight letters, and so, eight lines of holes and nos; in “colossus,” there are eighteen holes versus twenty-two nos. No eight-letter word could contain, say, three holes and thirty-seven nos. According to probability, every eight-letter word had to contain more than a certain number of holes, so Colossus was set to throw out results that contained fewer than that number. Colossus allowed the code breakers to concentrate on only the strips of letters that were more likely to resolve into the actual message.

  One flaw in the Lorenz machine, as a system of rings, was that somewhere in every message was a spot where the wheels returned to the start position. This meant that the encoding, though large and complex, was not perfectly random. Since the machine that the Germans were using was made of wheels and gears, it, according to Flowers, “generated and processed numbers” rather slowly—five every second. Colossus, because of the vacuum tubes, was a thousand times faster, its speed limited by the passing of the paper strip through the reader, not by the speed of the vacuum tubes. Since the Colossus was essentially a sorter, Flowers wanted it to sort as quickly as possible—and five thousand times per second was not fast enough, so a shift register was invented that read, counted, and kept track of five different readings of the holes each time the tape was passed through the machine. Colossus read and counted the holes so quickly that the code breakers could usually narrow in on the telling spot fairly quickly. Once they had done that, the pattern of the code was revealed, and the message could be broken. Colossus also had a mechanism for detecting and discounting spots where a message might have been incorrectly received.

  D-Day was set for June 1, 1944, but as it happened, the invasion was postponed because of the difficulty of moving troops and materials in bad weather. According to Andrew Roberts, when the chief meteorological officer, James Stagg, was handed the list of weather requirements that suited each faction of the invasion force, he said, “When I came to put them together I found that they might have to sit around for 120 to 150 years before they got the operation launched.” But there were concerns other than weather—principally the question of what the Germans thought the Allies were planning. On June 5, Eisenhower was interrupted in a staff meeting by a courier bringing the first Colossus-decoded German communication from Bletchley Park. Flowers writes, “Hitler had sent Field Marshall Rommel battle orders by radio transmission, which Bletchley Park had decoded with the aid of the new Colossus. Hitler had told Rommel that the invasion of Normandy was imminent, but that this would not be the real invasion. It was a feint to draw the troops away from the channel ports, against which the real invasion would be launched later. Rommel was not to move any troops. Eisenhower read the paper silently, then announced, ‘We go tomorrow.’ And on the morrow, 6 June, they went.”

  With the help of Colossus, the decoders at Bletchley Park then decoded Hitler’s subsequent messages to his armed forces and preempted his attempt to foil the invasion. According to Flowers, “The result was a defeat of the German Army so overwhelming that the Allies were able to sweep rapidly eastwards across France.” According to Roberts, Eisenhower also remarked to his staff, “I hope to God I know what I’m doing.” But Allied intelligence and counterintelligence worked so well that “even up to 26 June half a million troops of the German Fifteenth Army stayed stationed around the Pas de Calais, guarding against an invasion that would not come.”

  Flowers felt that he was the pivotal man in the success of Colossus because of his familiarity with vacuum tubes. He writes, “If I had … spent the war interned in Germany, Colossus would not have been built, because there would have been no one at Dollis Hill with sufficient knowledge of the new technology to make it. If Dollis Hill had not made Colossus, some other organization may have made something similar, but we now know that none could have done so by D-Day. Those chance events changed the course of the Second World War. If they had not, history would now record the devastation of Europe and a death toll much greater than actually occurred.” One key feature of Colossus’s success was that Flowers, like Eckert, realized that the vacuum tubes, which were seen as unreliable when he first began to use them, were much more likely to fail at the moment of thermal shock when being turned on. For the fifteen months that Colossus was at work, a machine was only turned off if it was malfunctioning.

  Flowers and his fellow inventors were not only proud of their machine, they were thrilled by it. The engineers who authored the report on Colossus at the end of the war (the report that was declassified in 2000) wrote:

  It is regretted that it is not possible to give an adequate idea of the fascination of a Colossus at work; its sheer bulk and apparent complexity; the fantastic speed of thin paper tape round the glittering pulleys; the childish pleasure of not-not [sic], span, print main header and other gadgets; the wizardry of purely mechanical decoding letter by letter (one novice thought she was being hoaxed); the uncanny action of the typewriter in printing the correct scores without and beyond human aid; the stepping of the display; periods of eager expectation culminating in the sudden appearance of the longed-for score; and the strange rhythms characterizing every type of run: the stately break-in, the erratic short run, the regularity of wheel-breaking, the stolid rectangle interrupted by the wild leaps of the carriage-return, the frantic chatter of a mot
or run, even the ludicrous frenzy of hosts of bogus scores.

  Flowers invented Colossus, but he also gave credit to Alan Turing for his contribution. At a conference in 1980, Flowers saw a young man reading the book that grew out of the BBC series The Secret War. The two struck up a conversation, and Flowers recalled, “You’d be working on a problem and not able to solve it, and sometimes someone would look over your shoulder and say, ‘Have you tried doing it like this?’ and you’d think, ‘Of course, that’s how you do it!’ With Turing, he’d say ‘Have you tried doing it this way?’ and you’d know that in a hundred years you would never have thought of doing it that way. And that was the difference.”

  In the course of the eleven months between D-Day and the German surrender in May 1945, the General Post Office built and the intelligence services made use of ten Colossus machines. According to Flowers’s obituary by Alan Blannin in the Daily Telegraph, “At the end of the war, all but two of the Colossus machines were destroyed. Flowers was ordered to destroy all evidence that they had ever existed. The two surviving machines were taken first to Eastcote, west London, the first home of the new Government Communications Headquarters, and then to its present base at Cheltenham, where a Colossus was still operational in the early 1960s.” Flowers, however, did not have access to them.

  The code breakers at Bletchley, even with ten Colossus machines, did not break every message, but the Germans did not expect them to be able to break any messages, and so they continued to use the Lorenz machine for high-level army communication even after they should have deduced from the failure of certain operations that something was wrong—in fact, Thomas Flowers worried about being too successful and thereby undoing all of his own work. There were other machines and other methods of encoding that the Germans used and the English did not break, but since the Germans chose to use the Lorenz machine for army communications at a time when the war was an army war across France and into Germany, Colossus was, in the eyes of its creators and others, the key to victory. It was this euphoria that led Thomas Flowers to accept the destruction of the Colossus machines and the ban on discussing either how the machines worked or what they had done between June 1944 and May 1945. The obituary in the Telegraph pointed out a further irony: “Flowers received very little remuneration from the government for his invention … barely sufficient to pay off the debts that he had run up while developing Colossus.” According to most sources his insufficient remuneration amounted to about £1,000 (some $40,000 in 2010 dollars, or about five times what Atanasoff had been granted for the development of the ABC).

  Charles Babbage, 1791–1871, inventor of the Difference Engine and Analytical Engine, analog computing devices. (Photograph courtesy of the Charles Babbage Institute, University of Minnesota, Minneapolis)

  A section of Babbage’s Difference Engine, showing rods and gears. (Science Museum/SSPL)

  Vannevar Bush with his Differential Analyzer, 1931. (Courtesy MIT Museum)

  John Vincent Atanasoff, around the time he completed his PhD at the University of Wisconsin. (Iowa State University Library/Special Collections Department)

  Atanasoff in the 1930s, teaching at Iowa State College. (Iowa State University Library/Special Collections Department)

  The physics building at Iowa State College. Atanasoff and Clifford Berry built the ABC in a corner of the basement. (Iowa State University Library/Special Collections Department)

  Clifford Berry, 1918–1963, standing with the ABC in 1942. (Iowa State University Library/Special Collections Department)

  An undated schematic of the ABC, prepared for a campus exhibition at Iowa State University. (Iowa State University Library/Special Collections Department)

  The ABC in May 1942. (Iowa State University Library/Special Collections Department)

  One of the ABC’s two electrostatic memory drums, the only surviving part of the original machine. (Courtesy of U.S. Department of Energy’s Ames Laboratory)

  Konrad Zuse’s Z1 computer, built in his parents’ Berlin apartment c. 1936.

  (Courtesy of Horst Zuse)

  Konrad Zuse, 1910–1995. (Courtesy of Horst Zuse)

  Alan Turing, 1912–1954, upon his election as a Fellow of the Royal Society in 1951. (© National Portrait Gallery, London)

  Bletchley Park staff at work on deciphering codes, Hut 6.

  (Bletchley Park Trust Archive)

  A Lorenz SZ42 Schlüsselzusatz cipher machine on display at Bletchley Park. (Bletchley Park Trust Archive)

  Thomas Flowers, 1905–1998. (Bletchley Park Trust Archive)

  Colossus at work in 1943; note paper tape.

  (Science Museum/SSPL)

  Aiken’s Mark I analog device in use, 1944.

  (Courtesy of the Computer History Museum)

  John Mauchly, 1907–1980 (left), and J. Presper Eckert, Jr., 1919–1995 (right), with Major General G. L. Barnes, 1944. (University of Pennsylvania Archives)

  ENIAC in 1946—Eckert stands front left, while Mauchly is by the column. (University of Pennsylvania Archives)

  John von Neumann with EDVAC in 1952; note Williams tubes along the bottom of the machine. (Alan Richards. photographer. From the Shelby White and Leon Levy Archives Center, Institute for Advanced Study, Princeton, NJ, USA)

  Chapter Seven

  With his family in Iowa, Atanasoff’s work in Washington was not favorable to his marriage, and then, in 1944, his daughter Elsie’s asthma took such a turn for the worse that it seemed essential that she be taken from Ames and moved to a more healthful climate. Atanasoff suggested Florida, which had worked for his father and siblings forty years earlier. Lura sold the house, packed up the children, and moved to Miami, but the move was not a success—Elsie did not improve, and marital relations did not improve. After living in Miami for about a year, Lura packed up the children again and drove west, looking for a livable climate for her seventeen-year-old daughter. By this time, the war was coming to a close and Atanasoff had to choose whether to return to Iowa State. He considered that his defense work was both essential to the war effort and well paid—he was making about $10,000 a year in salary (the equivalent of about $125,000 in 2010 dollars). His pay grade was above the congressional pay grade because his work was so productive. And his work fascinated him—always a prime consideration for Atanasoff. And then the navy asked him to develop a computer for them, a project that he of course could not resist. Lura and the children ended up settling in Boulder, Colorado, beautiful and neither hot nor humid. Elsie seemed to benefit, and Lura, inspired by the local scenery and by the colors of the native American art that she saw there, rediscovered her long-standing interest in painting. She set up her easel and was soon selling her work in local galleries. But Boulder, Colorado, was much farther from Washington, D.C., even than Ames, Iowa; the Atanasoffs drifted apart.

  It was at this time that Atanasoff made the acquaintance of perhaps the most mysterious but also the most famous contributor to the invention of the computer, mathematician John von Neumann. Von Neumann was a personable and charming man (even his biographer calls him “Johnny”). He would show up in the Naval Ordnance Laboratory to chat, and Atanasoff seemed to hit it off with him. Indeed, they had more than a few things in common. They were almost exactly the same age—von Neumann having been born at the end of December in the same year that Atanasoff was born at the beginning of October. Von Neumann’s father, Max, only a few years older than Atanasoff’s father, had moved from the small town of Pecs in Hungary to the cosmopolitan city of Budapest around the same time that Ivan Atanasoff had departed Bulgaria for the cosmopolitan city of New York. Just as the elder Atanasoff had married into the long-established Purdy family in upstate New York, Max von Neumann had married into a wealthy and established Jewish family in Pest. Both Atanasoff and von Neumann (whose name as a boy in Hungary was Neumann János Lajos) had been voracious students and enterprising learners, able, above all, to formulate pertinent questions and to see hidden connections among apparently disparate concepts.

>   But in other ways, their lives could not have been more different. Von Neumann’s boyhood had been ferociously urban and cosmopolitan. In the Jewish community in Budapest, von Neumann had grown up in a period and in a place remarkable for prosperity, education, talent, and exposure to a world of ideas and sophistication. Norman Macrae, von Neumann’s biographer, relates that in the late nineteenth century, enterprising Jews from all over Russia and eastern Europe flocked to Budapest, where changes in the culture meant that they could get ahead in the professions, if not in government, faster than they could in other, more conservative parts of Europe. In Budapest, Jews were welcomed—and educated, thanks to reforms instituted by a man named Maurice von Karman at the behest of Emperor Franz Joseph. But men like von Neumann’s father also went to Budapest instead of New York because it was more expensive for middle-class people to go to America than it was for poor people, who were content to travel in steerage. Macrae writes, “More steerage-class Jewish families settled on New York, and more upper-class strivers settled on Budapest.” Von Neumann’s generation of mathematicians and scientists from Budapest included Michael Polanyi, Leo Szilard, Edward Teller, and Eugene Wigner, but Budapest also produced great musicians (Antal Dorati, George Szell, Eugene Ormandy), moviemakers (Adolf Zukor, Alexander Korda, Michael Curtiz), photographers (André Kertész, Robert Capa), and writers (Arthur Koestler).