Chapter Seven.

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Mauchly had a lot to tell. He had become involved in a project at the Moore School, calculating trajectories for aiming large pieces of artillery. The proper aiming of a cannon had to take into account all sorts of factors: the elevation of the cannon and the elevation of the target, wind speed, wind direction, air temperature, humidity, and numerous others things. The variables were organized into firing tables, which were calculated by women employed by the Moore School working on Monroe calculators, but, as with Atanasoff"s calculations for the dielectric constant of helium, the calculations were tedious and time-consuming-the army was inventing and producing weapons faster than they could be put to use. At the Aberdeen Proving Ground, the Bush Differential a.n.a.lyzer-the a.n.a.log machine based on Babbage"s Differential a.n.a.lyzer and invented by Vannevar Bush, the man who was now the head of National Defense Research Committee-was making some headway on the necessary calculations, but the Bush a.n.a.lyzer could only solve differential equations with up to eighteen variables. Mauchly was aware of the army"s problem and now told Atanasoff about his new colleague, Eckert. He explained that the two of them were attempting to devise a machine that the army could use to make the necessary firing-table calculations.

Mauchly had submitted two proposals. The first, seven pages ent.i.tled "The Use of High-Speed Vacuum Tubes for Calculation," was submitted in August 1941 and described "an electronic device operating solely on the principle of counting." He suggested that it would do the same jobs as a.n.a.log machines, but do them more quickly. The army authorities in charge of research at the University of Pennsylvania apparently did not understand what he was getting at and also did not consider him a serious contender for research funding-one man, Carl Chambers, is quoted by Scott McCartney as saying, "None of us had much confidence in Mauchly at that time"-a sentiment Atanasoff would have agreed with.

The pivotal figure in Mauchly"s career was a twenty-eight-year-old lieutenant, Herman Goldstine, who happened to have a Phi Beta Kappa BA in mathematics and a PhD in ballistics from the University of Chicago. Before being drafted into the army, he had taught at the University of Michigan. Once he was drafted, a former professor found him a position at the Aberdeen Proving Ground. Goldstine was put in charge of the firing tables. When he took over, each table took a month to produce. Goldstine"s first thought was to hire more women to do the computations, but when his wife, Adele, also a mathematician, set out to find more female math students (female math students could do the calculations and were not as essential to actual combat operations), she could find only a few. The Bush a.n.a.lyzer was too slow and hard to maintain in working order. It was Goldstine who heard of Mauchly and his idea, and Goldstine who found Mauchly and asked him about it.

But neither Mauchly nor John Grist Brainerd, the Moore School"s liaison with the army, could find a copy of Mauchly"s seven-page proposal, now eight months old. At Goldstine"s behest, Mauchly, Brainerd, and Brainerd"s secretary put together as good a new proposal as they could come up with and took it to Aberdeen.

A major Allied setback that was not understood until after the war was the fact that the Germans also managed to crack English codes, specifically the code that routed convoys, Naval Cipher No. 3. Even though they did not have the benefit of a machine like the Bombe to do so in real time, they could often figure out the "size, destinations, and departure times," according to Andrew Roberts, but "instead of recognizing the danger, the Admiralty put the U-boats" remarkable success in intercepting convoys down to the advanced hydrophone equipment they used ... Naval Cipher Code No. 3 was not replaced with No. 5, which the Germans never cracked, until June 1943." The spring of 1943 saw the sinking, between March 16 and March 20, of twenty-seven Allied ships on their way from New York to Liverpool; 360 seamen died in the battle. Captain H. Bonatz, of the Beobachtungsdienst, a German naval code-breaking organization, later recalled, "The Admiral at Halifax, Nova Scotia, was a big help to us. He sent out a Daily Situation Report which reached us every evening, and it always began "Addressees, Situation, Date." " The rote repet.i.tion of the first words of the communication enabled the Germans to break the English codes every day in the same way that the repeated three-letter signal had helped the Enigma decoders. At Bletchley Park, the decoders could tell by what they were decoding that the Germans had access to Allied coded information. But code breaking in Germany was fragmented among various services and commands-there was never a well-funded center for deciphering Allied messages like Bletchley Park.

Turing, at this time, was in the United States. He spent a while at Bell Labs, working on a method for enciphering speech, where he discussed his paper "On Computable Numbers" with Claude Shannon. Shannon, himself a graduate of MIT, had written his master"s thesis in 1937 on using relay switches to solve Boolean algebra problems. He also had the insight, like Atanasoff, that the binary arithmetic that relay switches represented would simplify information systems. His master"s thesis, written when he was twenty-one and published when he was twenty-two, is considered to be one of the most important, if not the most important, master"s thesis of the twentieth century. Shannon had studied neurology, too. According to Hodges, when Turing and Shannon shared their ideas about "thinking machines" in March 1943, "they found their outlook to be the same: there was nothing sacred about the brain, and if a machine could do as well as the brain, then it would be thinking-although neither proposed any particular way in which this might be achieved." At the end of March, Turing returned to England on The Empress of Scotland.

It was in this context that Mauchly submitted his second proposal to Goldstine and Goldstine sought authorization from the army to fund the project-conditions seemed dire and the army was desperate enough to grant $61,700 (the equivalent of $750,000 in 2010 dollars) to Mauchly and Eckert.

According to McCartney, Mauchly and Eckert discussed their ideas casually-sitting around the Moore School and spending time drawing on napkins in a restaurant nearby. "A machine could be designed to do nothing but count the pulses of electrons, with the pulses representing numbers, and to crunch numbers in different ways to solve different problems. Instead of moving gears and wheels in a conventional calculating machine, Mauchly thought he could build a machine with no moving parts: only the electrons would course through the machine." Eckert agreed with and was inspired by the idea of electronic calculation-he had already devised a method of calculating smokestack emissions that sent a beam of light through a cloud of emissions. The amount of light that got through was then measured, giving a reading on the density of the emissions. There is no evidence that Mauchly and Eckert kept a record of their deliberations or that they elaborated on the theory behind the ideas that they pa.s.sed back and forth between their meeting in June 1941 and the submission of the first proposal in August 1942.

It was with his authorization in his possession that Mauchly came to visit Atanasoff at the gun factory in April 1943, but he said nothing about it. After chatting amiably for a while, he did ask Atanasoff a few questions about the ABC and about Atanasoff"s computer design ideas. Atanasoff, still underestimating Mauchly in several ways, was as forthcoming as he had been before. He felt, after all, that he and Mauchly were friends and that they were on good terms. He also had few opportunities to discuss his pa.s.sion for electronic calculation. It was only later, after thinking about their meeting, that Atanasoff wondered how Mauchly had gotten security clearance to visit him-to just show up. Though he asked around, he never got an answer to this question more satisfactory than the vague supposition that possibly Mauchly had connections, since his father was a Washington, D.C., scientific eminence.

After the first visit, Mauchly stopped by off and on, always chatting in a friendly way about personal matters before asking a few specific computer questions. At one meeting, he asked about the progress Iowa State was making toward patenting the ABC, but Atanasoff couldn"t answer that question with any certainty-he was working so hard at the NOL that he had neither the time nor the energy to keep after the college. Nor could Atanasoff say that he had kept on top of recent developments in computing-he was simply too busy. It seems clear from these conversations that Mauchly was using his access to Atanasoff both to probe him and to gauge whether the computer he was developing with Eckert might turn out to be profitable. The visits went on for three years.

Frugality was never a feature of ENIAC, which began to take shape in a large unused room at the Moore School in July 1943. At first the engineering team numbered twelve-Goldstine, Eckert, and Mauchly oversaw the general design (with Eckert in charge). Other members of the team were put in charge of individual components and, since the army was in desperate need of the firing tables, the Moore School team worked with seven-day-a-week dedication. Eckert"s most controversial decision was to use vacuum tubes-at first five thousand, a number that grew to eighteen thousand (in part because the army, in its desperation, pushed Goldstine to expand the capacity of the machine). Such a number was unheard of, not only because vacuum tubes themselves were considered unreliable, but also because wiring so many together would amplify the malfunction of any single one. But Eckert was determined to use the tubes and decided to make them less p.r.o.ne to burning out by obtaining only the best tubes and then operating them at a much lower voltage than recommended, as well as never turning the machine completely off-the current could be reduced to a trickle to keep the tubes warm and to guard against the potential danger of thermal shock.

Eckert was dedicated to testing every part. According to Scott McCartney, in order to choose his wiring, "Eckert acquired some mice in cages and starved them for a few days. Then he put different kinds of wire in their cages to see which kind they enjoyed eating. The least appetizing brand was used in ENIAC."

Eckert and Mauchly also decided to use a decimal counting system, sort of an electronic version of the Monroe calculator-if the number 345,679 was entered into the calculator, the counter in the ones column would flash nine times, the counter in the tens column seven times, the counter in the hundred column six times, and so on. But the tubes were much faster, of course, than a person tapping a calculator-a number would register in two millionths of a second. The advantages of speed were balanced by the dangers of unreliability, and so the machine, which was huge, had to have repairability built into it-it was so important that every tube be accessible in case it burned out that the machine was designed in discrete units with doors that opened into the mesh of wiring and tubes, and it took so much power to run the machine that Eckert had to include safety switches on every door to prevent electrocution. In addition, because the machine was decimally based, it could only add and subtract, not multiply, but Eckert"s idea was that it would be so fast that a binary number system would not improve overall performance and would require an extra piece of input- output hardware.

Like Zuse, Goldstine found help where he could-moonlighting telephone workers a.s.sisted with the wiring, Bell Labs supplied telephone parts and help with those parts, IBM designed a card reader for input and output. Goldstine, Mauchly, and Eckert seemed to work together quite well-Mauchly came up with the ideas but was considered by the others to be easily distracted. Eckert followed through, realizing the ideas in the machine and making sure that his designs were properly executed-he was noted for his perfectionism (and appreciated, in light of the expense and the danger of what he was putting together). Goldstine found the money, organized the personnel, and was the liaison with the army. He got along well with Eckert, but not well with Mauchly, who seemed like "a s.p.a.ce case" to him. Eckert, it was clear to everyone, depended on Mauchly, but no one knew exactly why, even Mauchly. Since Mauchly was teaching at the same time, he wasn"t present at the building site as much as the others were. In 1944, when his teaching load was cut back so that he could work full time on ENIAC, his salary was cut from $5,800 to $3,900, leading to even more anxiety on his part. But he still felt that the project was his because he had originated it. It was at this point that he applied for a part-time job at the NOL, in the statistics department, and used Atanasoff as a reference. Atanasoff later said that he gave Mauchly a good recommendation more out of friendship than out of faith in his talents or expertise, but Mauchly got hired.

Mauchly mentioned his machine the first time in early 1944-according to Tammara Burton, "He looked Atanasoff in the eye and told him that he was building a new computer. The new computer, Mauchly claimed, isn"t "anything like your machine"; but is "better than your machine." " When Atanasoff had asked about the new computer, Mauchly put him off, saying that it was top secret. Though Atanasoff"s security clearance was higher than Mauchly"s, Atanasoff knew he would not get anywhere by pressuring the other man. Atanasoff still believed at this point that Iowa State was likely to have filed the patent application. He knew that he himself would not have stolen another man"s ideas, so he didn"t suspect Mauchly-indeed, Mauchly a.s.sured him that the principles behind the ENIAC were entirely different from those behind the ABC. A few months later, in August 1944, Atanasoff met J. Presper Eckert for the first and only time, when Mauchly brought him to the gun factory in search of help with quartz transducers. Since Eckert did not have a high security clearance, the two men had to have a military escort, so the visit was brief and unrevealing. Although Atanasoff had agreed to help with the quartz transducers, he didn"t see Mauchly again. It was only later that it occurred to him that quartz transducers could be used in a computer to regenerate memory.

When it was completed, ENIAC was huge. It weighed twenty-seven tons, was eight feet long, eight feet high, and three feet deep. In addition to the 18,000 vacuum tubes, there were 7,200 diodes, 1,500 relays, 70,000 resistors, and 10,000 capacitors for memory storage. It required 150 kilowatts of power, the equivalent of 1,500 100-watt lightbulbs. Because of potential failure of the vacuum tubes, the machine was rarely turned off, but it did malfunction-Eckert said in 1989, "We had a tube fail about every two days and we could locate the problem within 15 minutes." ENIAC was not a programmable computer-its switches had to be set and it had to be wired to perform its task; if the task changed, it had to be rewired and the switches reset. This could take weeks. The fact that ENIAC was not programmable was a by-product of the speed with which it was built. In his 1943 progress report, Brainerd rejected the added complexity such a feature would introduce-like Atanasoff, he didn"t want to fall into the trap Babbage had fallen into.

As the war progressed in Germany, Konrad Zuse continued to exercise his special genius, which was not just working hard on innovations to his machine, but also making and using all sorts of social connections to circ.u.mvent the increasing difficulties of finding materials and developing new ideas. As he began putting together the Z4, he cultivated acquaintances at the telephone exchange who had managed to avoid being drafted into the armed forces by making themselves appear more essential to the operation of German communications systems than they actually were. These "young, energetic, and enthusiastic" friends had access to junk bins, where over and over they turned up parts that Zuse could make use of. And Zuse"s own day job contributed to his understanding of what a computer might do-at one point, he devised a machine for Henschel that calculated optimum wing dimensions for innovative aircraft, a machine that worked fairly reliably for two years. This machine led to another machine designed to "mechanize dial gauge reading." Although this machine was completed, Zuse had to abandon it almost as soon as he constructed it-he never learned whether it was blown up at the end of the war, or whether the Russian forces captured it. He writes, "Even as I was putting it together, the order came to dismantle the just-completed factory ... But I went on working like a madman, driven solely by the ambition to see this interesting machine actually work at least once. Finally, it was created-the first process controlled computer. Even if not a single person had been interested, I had the pleasure of solving a difficult problem once again."

Zuse and his colleagues began on the Z4 in 1942, building the machine in Berlin in the midst of air raids and fire bombings. On one occasion, Zuse was climbing the stairs in his office building and had just come to a landing when he heard "a crackling sound overhead." As soon as he ducked into a nearby doorway, the staircase crumbled away. He managed to get down to the cellar and attempted to put out fires with a portable fire extinguisher, but the building burned to the ground anyway. All told, the Z4 had to be moved three times within the city limits of Berlin during the war. Even as Zuse persisted, he writes, "I didn"t always reach the cellar in time" to find safety-sometimes the air raid warnings would sound at just the time he was ready to test some function. But Zuse was dedicated-when he writes about building the Z4 during the war, he suggests that he was more fearful of the computer not functioning than he was of more mortal outcomes: So, of course, when after weeks or months of work, I know that the time has come for the device to perform without a hitch, then the moment when the start b.u.t.ton is to be pressed is especially tense. I always had a p.r.o.nounced fear of such moments ... It takes good nerves to withstand something like this for years on end.

Zuse was not entirely cut off from the outside world, but communication channels were idiosyncratic. At one point, Zuse"s bookkeeper told his own daughter about what Zuse was inventing. The daughter, who worked for German intelligence, responded by reporting that a similar machine was being developed in the United States. Zuse concocted the ruse of sending two a.s.sistants to the intelligence offices, where they presented what looked like an official doc.u.ment from the Air Ministry, asking to see the information. They were turned down, but since they had been told which drawer the photo was in, they managed to find it and bring it back to Zuse. The photo was of Howard Aiken"s Mark I. Zuse could not infer many technical details from the photo, but he became further convinced that computer development would have many, many applications in the postwar world. Unfortunately, in Germany, "hardly anyone could imagine commercial applications for our machines. Civilian production would also have been out of the question; it was officially forbidden."

But Aiken"s Mark I, a machine that looked sleek and elegant (and huge) in the photograph Zuse saw, had a history in some ways as troubled as any of the other machines. Like most of the other scientists working on computers, Aiken joined the war effort (the Naval Reserve) once his PhD was completed. When IBM began building the Mark I (and, subsequently, Mark IIIV), IBM engineers began modifying Aiken"s design. The result was that Aiken became less and less involved with the final design features-the machine was taken over by the inst.i.tutions that financed it. As the computer approached completion, IBM and Harvard made elaborate plans to unveil it in a joint ceremony. IBM, having spent half a million dollars ($6 million in 2010 dollars) building the machine, was eager to fully share the credit for its design and implementation. Aiken, however, seems to have done something-possibly contacting the press-that shifted the emphasis away from IBM and toward Harvard. Thomas J. Watson, Jr., later said, "If Aiken and my father had had revolvers they would both have been dead." Hard feelings lingered for years afterward.

Alan Turing is now a famous man-the subject of biographies, papers, an opera, and at least one play, but his work at Bletchley Park breaking the Enigma code did not come to light until the 1970s, and then, at first, only by means of popular books that did not actually mention him, or mentioned him in cryptic ways (F. W. Winterbotham, The Ultra Secret, 1974; A. Cave Brown, Bodyguard of Lies, 1975), or in specialized publications that did mention him directly (Brian Randell, "On Alan Turing and the Origins of Digital Computers," 1972; Brian Randell, editor, The Origins of Digital Computers: Selected Papers, 1973). Various accounts culminated in an episode about Turing and Enigma in a 1977 BBC series called The Secret War (other episodes concerned radio beams, radar, magnetic mines, and the V-1 and V-2, prototype German cruise missiles). Turing"s genius then captured the popular imagination, but so did his life, which was idiosyncratic, dramatic, and tragically short-he was not only a genius full of charming eccentricities and in some ways a paradigmatic Englishman, he was also an unashamed h.o.m.os.e.xual. Andrew Hodges, Oxford mathematician and gay activist, published his dense biography of Turing in 1983, which focused equally on Turing"s life and on his work. But there was much more going on at Bletchley Park between 1941 and 1944 than the cracking of the Enigma code.

The essential difference between Enigma messages communicated to German ships and Tunny messages was that Enigma messages were hand encoded, then communicated by radio broadcast, then hand decoded, while Tunny messages, also communicated by radio broadcast, were machine encoded and decoded, therefore not as subject to the human errors that allowed the English decoders to break the Enigma. The Tunny messages were also much more complex. The German army set up a radio network between Ukraine in the east, Brittany in the west, Tunis in the south, and Oslo in the north. Some stations were fixed, but most consisted of two equipment-carrying trucks, one with a sending Lorenz machine, a receiving Lorenz machine, and a teleprinter, the other with radio equipment.

Although in the early 1980s Tommy Flowers was given permission to describe the workings of the code-breaking machine named Colossus that he and his team of engineers built at top speed in 1943, he was forbidden to say what the machine had done or how it had been used in the war. It was only toward the very end of Flowers"s life, when the United States decla.s.sified some communications by American liaisons at Bletchley Park that mentioned Colossus and described its function, that the importance of the machines began to emerge (there were ten of them, the first Mark I that Flowers designed and built in 1943, and the nine Mark 2s that were larger and faster, built in 1944). In 2000, the British government finally decla.s.sified a long report on Colossus, written by code breakers in 1945, that revealed not only the complexity of Colossus but also its importance-and it was dramatically important.

The job of the Colossus team was the same as that of the Bombe builders-to infer by means of technical and theoretical deduction what the mechanical Lorenz encoding machines were doing and how they worked, and then to build a machine that mirrored that structure. In a teleprinter machine, upon which the Lorenz was based, a long strip of paper about an inch and a half wide pa.s.sed through a slot the way a piece of paper pa.s.ses over the roller of a typewriter, short end first. It was advanced by means of a line of tiny sprocket holes about three-fifths of the way between the left edge and the right edge. The pattern of holes standing for each letter of the alphabet and other essential characters according to the Baudot-Murray code, which had been invented by Emile Baudot in 1870, ran across the strip, three holes to the left of the sprocket holes and two holes to the right. The five positions in each row, some punched and some unpunched, represented a letter of the alphabet. For example, the letter M was represented as hole/hole/hole/no/no (or x x x . .) while the letter N was no/hole/hole/ no/no (or .x x . .). A message communicated by a normal teleprinter (or teletype machine, as it was called in the United States) consisted of a long blank strip of paper to indicate that a message was beginning, followed by a strip riddled with lines of holes, the length of which depended on the message, which was followed by another empty strip that indicated the end of the message. Since every letter consisted of five positions (hole or no), a six-letter word, such as "letter." would consist of six lines. The words of the message ran down the strip: the word "colossus" would have looked like this: Obviously, such a way of representing letters is time-consuming to generate by hand but easy by machine, easier than Morse code because the machine can punch an entire line at one time.

The job of the Lorenz machine was to take the principle of teletyping and encode the message so that it would be indecipherable except by the target Lorenz machine set to the same key as the originating machine. Since a teletype machine is based on the binary principle that a letter consists of five positions, some of which are punched ("1") and some of which are not punched ("0"), then the machine used a binary arithmetical process to create the code. In Colossus, Jack Copeland calls this "the Tunny Addition Square" (appendix 3). The letters and symbols in the coded message were pa.s.sed through the machine and "added" to letters in what was called the "keystream," or the entirely different order of letters and symbols produced by the machine. The rules of addition were that 0 + 0 = 0, 1 + 1 = 0, 0 + 1 = 1, and 1 + 0 = 1 (note that this addition square is like Boolean algebra, but the values a.s.signed to the results are specific to the rules of the Lorenz machine-it was not a mathematical machine and was not designed to solve math problems). The products of the addition of the coded letters to the keystream letters were systematic, and because the system was binary, if the Tunny receiving machine was set to the same keystream, all it had to do was take the coded message and add the letters and symbols of the keystream to the coded message, and the original message was retrieved. The Tunny Addition Square has 1,024 possible results (just like a base-ten multiplication table has 100 possible results). The more levels or "wheels" the machine employed, the more shifts were possible, and the German encoders employed the twelve wheels of the Lorenz machine in different ways, all of which were organized by headquarters. What the English eavesdroppers soon realized was that part of decoding the message was getting hold of the key (often transmitted between operators by hand) and using it to sift through the messages (transmitted by machine). However, what Turing understood was that with twelve different wheels, the number of possible variations was more enormous than human decoders could manage. Wheels 15 operated together (the code breakers called these the "psi" wheels after the second-to-last letter of the Greek alphabet). Wheels 812 also operated together (the "chi" wheels, after the third-to-last letter of the Greek alphabet). Wheels 6 and 7 were called the "motor" wheels. Each wheel had a number of positions-wheel 1 had forty-two positions, wheel 2 had forty-seven positions, for example. The job of the code breakers at Bletchley Park was to decipher the patterns in each set of teleprinted letters so that each shift of each wheel could be peeled away to reveal the original message. Intercepted encoded paper tapes were the raw material that Colossus had to process. Uncovering the shift pattern of one of the encoding wheels of the Lorenz machine was the key-once the position of the first wheel was ascertained, the positions of the next wheels became progressively easier to ascertain through Boolean logic. But while Enigma had three wheels, and then four, which was difficult enough, the Lorenz machine"s twelve wheels hugely enlarged the number of possibilities that had to be tested. And though sometimes with Enigma, the German operators encoding and sending the messages made mistakes that gave away the pattern, the mechanization of the Lorenz encoding process gave rise to fewer human errors, which was a large part of the reason Tunny was more difficult to decode.

In order to gain some idea of the work Colossus had to do, let"s imagine a message of five hundred holes and s.p.a.ces representing one hundred letters (a very short message). It was the job of German intelligence officers to designate the positions and of the Lorenz operators to set the positions. Until the summer of 1944, the position of the psi wheels was set monthly and the chi wheels quarterly, then monthly. The motor wheels were set daily. As the war heated up in 1944, the positions of all the wheels changed daily.

The Dollis Hill communications research laboratories were located about eight miles northwest of central London, in an area that had originally been farms, then the estate of a politician who was a friend of William Gladstone and who had served as governor-general of Canada and lord lieutenant of Ireland. As close as it was to central London, the area retained its rustic feel into the twentieth century. But by the First World War, the team designing the Liberty tank, Mark VIII, was based there, and in 1921 the English government established the Post Office Research Station there. By 1933, a large brick factory and offices had been built, and at the beginning of World War II an underground bunker called Paddock was installed (though Churchill didn"t like it and wouldn"t stay there). The parts of the Colossus were shipped to Bletchley Park (about an hour"s drive farther northwest) and a.s.sembled there.

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 a.n.a.logue 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 pa.s.sed 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 pa.s.s of the loop through the scanner included a blank section that defined the beginning and the end of the message. The tape pa.s.sed 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 pa.s.sed 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 pa.s.sing 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 pa.s.sed 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-princ.i.p.ally 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 G.o.d 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 auth.o.r.ed the report on Colossus at the end of the war (the report that was decla.s.sified 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 motor 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, 17911871, inventor of the Difference Engine and a.n.a.lytical Engine, a.n.a.log computing devices. (Photograph courtesy of the Charles Babbage Inst.i.tute, University of Minnesota, Minneapolis) A section of Babbage"s Difference Engine, showing rods and gears. (Science Museum/SSPL) Vannevar Bush with his Differential a.n.a.lyzer, 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 bas.e.m.e.nt. (Iowa State University Library/Special Collections Department) Clifford Berry, 19181963, 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, 19101995. (Courtesy of Horst Zuse) Alan Turing, 19121954, 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 Schlusselzusatz cipher machine on display at Bletchley Park. (Bletchley Park Trust Archive) Thomas Flowers, 19051998. (Bletchley Park Trust Archive) Colossus at work in 1943; note paper tape.

(Science Museum/SSPL) Aiken"s Mark I a.n.a.log device in use, 1944.

(Courtesy of the Computer History Museum) John Mauchly, 19071980 (left), and J. Presper Eckert, Jr., 19191995 (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, Inst.i.tute 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 Janos 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 inst.i.tuted 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-cla.s.s people to go to America than it was for poor people, who were content to travel in steerage. Macrae writes, "More steerage-cla.s.s Jewish families settled on New York, and more upper-cla.s.s 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 (Andre Kertesz, Robert Capa), and writers (Arthur Koestler).

In 1914, when eleven-year-old John Atanasoff was attending a one-room schoolhouse in Florida, helping his father rewire the family house, learning to maintain, repair, and then drive the new Model T, as well as frustrating his teachers by surpa.s.sing them, Neumann Ja.n.u.sz (called "Jancsi") was delighting his teachers, who were some of the best mathematical minds in Europe. n.o.bel Prize winner Eugene Wigner recalls, in Kati Marton"s The Great Escape, that "he was one grade below me, but in mathematics, two cla.s.ses ahead. He already had an astonishing grasp of advanced mathematics ... The way he described set theory and number theory was enchanting. The beauty of the subject, his intensity and facility of description made me feel we were close friends." One well-regarded teacher tutored von Neumann without compensation, according to Wigner, for the sheer pleasure of "the brush with a special kind of mind." There were other tutors, too. According to Macrae, "Before he finished high school [he] had been accepted by most of the university mathematicians as a colleague." Jancsi was not a pest. He naturally and willingly fit in with his fellow students (Wigner recalled, "He joined in cla.s.s pranks just enough to avoid unpopularity") and pleased his teachers. He was so adept at mathematics that he could do difficult problems in several ways and gear his solution to the educational level of his a.s.sociate if he had to. Perhaps we may say that whereas Atanasoff was a natural fixer and improver, von Neumann was a natural game player, always aware that the moves in any game could be made in more than one way and that each possible move would lead to a different outcome, which would in turn lead to other, different outcomes. And game playing, too, as demonstrated by Turing"s fascination with chess, was an aspect of computer innovation.

In 1920, when Neumann Ja.n.u.sz was seventeen, educational circ.u.mstances changed for Jews in Hungary. In a place where the vast majority of educated professionals (50 to 80 percent) were Jews, the postWorld War I government inst.i.tuted anti-Semitic quotas for university places-no more than 5 percent. By June 1921, when Atanasoff had saved enough money teaching and working so that he could attend the University of Florida, von Neumann was taking his exams (and worrying so much that as a result his papers were not perfect). In Gainesville, Atanasoff wanted to be a physicist, but the university offered electrical engineering, so he studied that. In Budapest, von Neumann wanted to be a mathematician, but conditions in Hungary made that impractical, so his father pushed him toward chemical engineering. Ironically, when, in September, Atanasoff left Brewster for Gainesville, von Neumann left Budapest for Berlin. But in this, too, he fell into the center of the world, or at least of the mathematical world. Marton writes, "From all over the globe, theoretical physicists gathered in Berlin, and in the medieval university town of Gottingen, three hours away. In those last years before the darkness fell on Germany, a revolution was taking place in the way we understand s.p.a.ce and time." This revolution was quantum mechanics, the very subject that Atanasoff was taking from John Hasbrouck Van Vleck at the University of Wisconsin at about the same time, and proving that he could comprehend in spite of a late start and missed cla.s.ses.

By the time von Neumann encountered Atanasoff, he had exceptional connections, not only because he was a genius, and not only because he had been born and educated at the center of things, but also because he was worldly, charming, and personable-a connector as well as a maven, in Malcolm Gladwell"s terms. After completing his degrees at Berlin and Zurich (where a paper he wrote was sent to David Hilbert, the man who posed the problem that Turing addressed in "On Computable Numbers," and so impressed him that he a.s.siduously cultivated the young man), von Neumann went to the University of Gottingen in 1926, just about the same time that Atanasoff was first at Iowa State (and Flowers first went to work at Dollis Hill). In 1930, von Neumann was invited to Princeton, and two years later he was given a professorship at the Inst.i.tute for Advanced Study, along with Albert Einstein and Kurt G.o.del. It was there that he met Alan Turing, to whom he offered the job as research a.s.sistant in 1938. Clearly, von Neumann"s personality and biography meshed to produce a man who was perhaps preternaturally political in a way that was unusual in a mathematician or an inventor-he was not only completely at ease in all sorts of social situations, he was extraordinarily aware of the ramifications of larger sorts of politics. He was, after all, the man who was a.s.signed to do the calculations at Los Alamos that were to estimate exactly how much damage an atomic bomb might be made to inflict upon the j.a.panese. His specific task was to calculate at what elevation the detonation should take place in order to achieve the greatest possible destruction. Other Manhattan Project physicists, notably Leo Szilard, von Neumann"s slightly older compatriot, preferred an intimidating demonstration of the weapon, but von Neumann was willing to make a list of good targets-according to Norman Macrae, he was instrumental in steering the air force away from the Imperial Palace, but, according to Kati Marton, he thought the j.a.panese holy city of Kyoto was a good target (of course, the final targets were Hiroshima, a shipping center and supply depot, and Nagasaki, a ship-building center).

Physicist Stanley Frankel, who performed many of the Manhattan Project calculations that predicted whether or not an atom bomb could be made to explode, and what would happen then, later said that von Neumann was aware of "On Computable Numbers" by 1942 or 1943 and made sure that Frankel studied it (Frankel went on to be a computer consultant after the war). With his experience on the Manhattan Project, von Neumann was one of the most influential scientists in the world.

But of course, although everyone knew that von Neumann was a genius, and an important man, in the summer of 1944 the Manhattan Project was highly cla.s.sified, and in 1944, although one type of bomb had been developed (Little Boy), the method for detonating a more powerful bomb had not been worked out. Just about this time, von Neumann was approached by a young man on a train platform. The young man was Herman Goldstine. Goldstine went up to the famous mathematician (whose lectures he had once attended) and introduced himself, but von Neumann got friendly only when Goldstine began to chat about his (highly cla.s.sified) work on a computer. A month later, in August, von Neumann visited ENIAC in Philadelphia for the first time. Von Neumann may have been a famous genius, but according to Norman Macrae, Pres Eckert, then twenty-five, viewed von Neumann"s visit as a test-for von Neumann. Eckert said to Goldstine that he would find out if von Neumann was really the genius he was supposed to be "by his first question. If this was about the logical structure of the machine, he would believe in von Neumann. Otherwise, not." Forty-one-year-old von Neumann pa.s.sed the test.

By the time of von Neumann"s visit, work on ENIAC had been moving at a fever pitch for fifteen months, but the speed of construction demanded by the army because of the difficulty of creating the firing tables meant that real innovation in every aspect of the machine (Mauchly"s and especially Eckert"s goal) had not been possible. They had to use parts that were already in existence (and because the machine was a low priority to the military, a percentage of these parts were defective, though not actual discards, like Zuse"s parts) and at least some ideas that derived from machines that were already familiar to the army, including Irven Travis"s machine at the Moore School that Mauchly was already familiar with by the time he met Atanasoff. Von Neumann grasped that the really new machine would be the next version, and Eckert grasped that, too-he had already begun making drawings for it.

After meeting Goldstine, Eckert, and Mauchly, and chatting with Atanasoff at the NOL (and, no doubt, with anyone else who seemed to know about computer theory), von Neumann went back and forth to Los Alamos, where he worked on the Manhattan Project-it wasn"t until December of that year that the detonation device for one of the bombs (Fat Man) was successfully tested. Work continued on the bomb, but in June 1945, von Neumann was not so busy at Los Alamos that he did not have time for other things-under his direction, Herman Goldstine wrote a description of an idea for the second version of ENIAC. The paper was 101 pages long and was ent.i.tled "First Draft of a Report of the EDVAC, by John von Neumann." EDVAC stood for "Electronic Discrete Variable Automatic Computer." Mauchly and Eckert were told that the paper was "an internal summary of their work," and Goldstine also told another concerned party that it was meant for internal use only; therefore it did not const.i.tute cla.s.sified material and could be reproduced. The fact that von Neumann was given sole authorship at first seemed to Mauchly and Eckert insignificant. The purpose of the paper, and its achievement, was that it expressed the logical and overarching theory of what the creators of ENIAC were trying to do, something that Eckert had hardly had time to attempt, and Mauchly had not been inclined to do, even though he had the time. Eckert had written a three-page memo in February 1944, describing a system for storing electrical impulses. A notable feature of Goldstine"s paper was that even though Eckert had described what he was building to von Neumann in August 1944 and subsequently, there was no mention of Eckert and only one mention of Mauchly (though Howard Aiken was mentioned several times). Partisans of von Neumann make the case that, as with everything else von Neumann did, he took the raw material of another man"s ideas and immediately transcended it, or, as Macrae says, "Johnny grabbed other people"s ideas, then by his clarity leapt five blocks ahead of them, and helped put them into practical effect."

The most important contribution of the "First Draft" to computer design was that it laid out what came to be known as "von Neumann architecture"-that is, that the computer could contain a set of instructions in its memory like the set of instructions that Turing"s human "computer" would have been given and would have to follow day after day forever. The instructions would be stored in the memory, which the electronic computer could readily access (not like a paper tape or a deck of punch cards). This set of instructions in the memory would be called a stored program. Von Neumann described these ideas in terms of physical structures that had access to one another-the control unit was a self-contained s.p.a.ce that could communicate back and forth with the memory. Separate from the control unit was the logic unit (conceived as a place where mathematical calculations were performed), which also communicated back and forth with the memory. The control unit and the logic unit communicated back and forth with each other. The problem to be solved, the input, was fed into the logic unit, and the solution, the output, emerged from the logic unit. But really these "places" were not physical structures-they were sets of instructions, an idea that von Neumann may have (or seems to have) gotten from "On Computable Numbers." According to Macrae, "The primary memory would be fairly small, with rapid random access. Behind it would be a secondary memory. It should be able to transfer information into the primary memory automatically, as needed. The computer should be able to move back and forth through the secondary memory. Individuals should be able to enter information directly into the secondary memory."

Although ENIAC was an army project and the war was still on when Goldstine wrote the paper, over the next few months Goldstine sent von Neumann"s report to twenty-four of von Neumann"s colleagues and friends in the United States and England. Their response was enthusiastic and included requests for more copies. Goldstine eventually sent out hundreds. It was this that finally alarmed Mauchly and Eckert, who wrote their own paper in September, describing their ideas for EDVAC and more carefully ascribing particular ideas to particular partic.i.p.ants in the ENIAC project, but they hadn"t the gift-their report was neither as detailed nor as eloquent as Goldstine and von Neumann"s in conceptualizing the larger implications of the project. Nor did they have the connections or the reputation. Most important, they did not have the cooperation of the boss, Herman Goldstine. Goldstine, who was in charge of security cla.s.sification for the project, marked Mauchly and Eckert"s report confidential, thereby ensuring that, unlike von Neumann"s report, it would not be widely read or, perhaps, read at all. There is no evidence that, even though von Neumann was in contact with Atanasoff because of the navy project, he gave Atanasoff a copy of the report or told him about it. Nor did Mauchly and Eckert send Atanasoff a copy of their report, even though his security clearance was higher than theirs.

Although Atanasoff was invited to the February 1946 unveiling of ENIAC at the University of Pennsylvania, and attended, the demonstration of the machine did not clear up any mysteries for him about how the machine worked or the principles behind it. And Mauchly and Eckert were not present. The purpose of ENIAC was to accomplish what Mauchly had originally proposed-the calculation of artillery trajectories. It was so enormous and so expensive that Atanasoff was intimidated. Even so, not long after he saw the ENIAC, Atanasoff called Richard Trexler, the patent attorney in Chicago. Trexler told him that Iowa State had never paid to file the patent application, and so he had not filed it. Atanasoff knew that his moment to patent his ideas was lost-ENIAC convinced him that computers had progressed. Either his ideas were obsolete or they were irrelevant. Computer technology, it was readily apparent, was now established and developing apace.

In Germany, in 1943 and 1944, Konrad Zuse was still hard at it, still undaunted in attempting the impossible. Even the small prototype using vacuum tubes that Herbert Schreyer wanted to build seemed to be impossible-the type of tubes they needed were not being manufactured in Germany. But while a friend at the Telefunken company made ten tubes in his spare time and smuggled them out of the lab, they discovered that they had another sort of access to materials: Dr. Schreyer was able to get [the German Aeronautics Inst.i.tute] a.s.signed the task of examining the intended uses of mysterious devices found in shot-down American and British aircraft ... After such an examination, a huge number of completely modern components, resistors, small cylindrical capacitors, variable capacitors, the most modern miniature tubes and small batteries, etc. were left over. Never again did we lack parts which we needed ad hoc for developing the computing machine; we had so much left over, we were able to set up a flourishing radio repair shop.

The conditions surrounding the invention of the Z4 were astonishing-every morning, the inventors had to clean up damage and debris from bombings of the night before. One morning, Schreyer decided he needed, as a conductor, a piece of c

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