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Zuse, Konrad


(b. Berlin, Germany, 22 June 1910;

d. Hünfeld, Germany, 18 December 1995), logic, computers, programming, computer industry.

Zuse is popularly recognized in Germany as the “father of the computer,” having built the world’s first programmable computing machine in 1941. Zuse is less well known in other countries because most of his early computers were built during World War II and became famous in and outside Germany only several years after the war.

Early Years. Konrad Zuse was born in Berlin to Emil and Maria Crohn Zuse. His father was a Prussian civil servant working for the postal service who relocated the family to Braunsberg (now Braniewo in Poland) when Konrad was still a child. Konrad attended elementary school in that town and began studying at the local Gymnasium Hosianum. The family moved again in 1923 to Hoyerswerda (a town in Germany near what is now the border with Poland). In Hoyerswerda, Zuse was registered at the Realschule, a school that allowed pupils to continue studying at any of the several technical universities established in Germany. The family eventually moved back to Berlin and Konrad Zuse began his studies at the Technische Hochschule Charlottenburg (renamed Technical University of Berlin after World War II). Zuse started studying mechanical engineering, changed to architecture, thought for some time of becoming a commercial graphic designer, and settled finally on civil engineering. Years later Zuse wrote in his autobiography that he eventually discovered civil engineering to be the ideal field for him because he could combine his artistic interests with his technical prowess, especially regarding mechanical constructions. The young Konrad Zuse was an inventor and a tinkerer, often withdrawing to work with his “Stabil” mechanical set (a German version of the Meccano or Erector Set). As a student he won several prizes for his constructions, which he enjoyed showing off.

As part of his civil engineering studies at the Technische Hochschule, Zuse learned to perform repetitive static calculations like those needed to determine the stress on materials of structures such as bridges or cranes. Static calculations were performed completely by hand or with the help of desk calculators. Spreadsheets, on which all necessary formulas had been preprinted, were laboriously filled row by row. It was tedious and repetitive work that led Zuse to consider the possibility of automating the task. If engineers simply had to fill in data and follow a fixed computational path, then a machine could take over.

The Mechanical Programmable Machine. After his graduation in 1935 Zuse started working as a stress analyzer for the airplane manufacturer Henschel Flugzeugwerke. He kept this position for less than a year, resigning with the purpose of starting his own company. He wanted to build automatic calculating machines and had already made contact with Kurt Pannke, a constructor of mechanical desk calculators. However, Zuse’s short-lived employment at Henschel would prove crucial for him in later years: Twice in his life his superiors at Henschel would help him secure a deferment from the army, both times arguing that he was needed as an engineer and not as a soldier on the battlefield.

In 1936, with his parents’ financial support, Zuse began to build the automaton that so far had only existed in his imagination. Some friends at the university assisted by working for him while others offered small monetary contributions so that he could finish what would become the machine V1 (Versuchsmodell 1, “experimental model one”). Perhaps the most important difference between Zuse and other computer inventors working in the late 1930s was that Zuse was designing his machine essentially alone, whereas in the United States scientists such as John Atanasoff and Howard Aiken had the resources of universities or important companies at their disposal. The entire mechanical conception of the V1 (later renamed to Z1) was his brainchild.

Zuse, ignorant of the internal structure of any type of calculator built at the time, started from scratch and developed an entirely new kind of mechanical assembly. Whereas contemporary desktop calculators were based on the decimal system and used rotating mechanical components, Zuse decided to use the binary system and metallic shafts that could move only in one direction. That is, the shafts could only slide from position 0 to position 1, and vice versa. Such shafts were all that was needed for a binary machine, but important obstacles had yet to be surmounted. It was necessary to design the complete logical description of the machine and then “wire” it accordingly. The mechanical components, however, posed a formidable challenge because every movement of one logical gate had to be mechanically coupled with the movement of the other gates. Horizontal displacements of the components had to be transformed into sliding displacements across different layers of the machine, or even into vertical displacements. From an early twenty-first century perspective, the mechanical design of the machine was much harder than conceiving the pure logical structure. It is fair to say that none of Zuse’s friends understood exactly how the machine worked, although they spent weeks manufacturing the hundreds of metallic shafts needed for the apparatus.

The Z1 was operational in 1938. It was shown to several people who saw it rattle and compute the determinant of a three-by-three matrix. The machine, however, was not reliable enough. The mechanical components, all machined at home, had a tendency to get stuck. Nevertheless, the mechanical Z1 proved that the logical design was sound. Therefore, an electrical realization, using telephone relays, could be contemplated as the next step. Helmut Schreyer, an electronics engineer and college friend of Zuse, suggested the use of vacuum tubes. Schreyer, in fact, adopted this as his PhD project and developed some vacuum tube circuits for an electronic machine. Zuse, however, was not convinced that vacuum tubes should be used, although they promised extremely fast calculations. He doubted that in the long run vacuum-tube machines could be made to perform as reliably as relays or even mechanical components. Zuse had already been contemplating possible uses for his machine: His goal was the development of a programmable replacement for

mechanical desktop calculators for deployment in large or medium-size companies. This was to be a “computing machine for the engineer,” eventually so small that it could be placed on top of a desk.

In 1938 Schreyer and Zuse explained some of the electronic circuits to a small group at the Technische Hochschule. When asked how many vacuum tubes would be needed for a computing machine, they replied that two thousand tubes and several thousand other components would be enough. The academic audience was in disbelief: The most complex vacuum circuits at the time contained no more than some hundred tubes, and the electric power necessary to keep such a machine working would be prohibitive. Just six years later the ENIAC, built at the Moore School of Electrical Engineering in Philadelphia, would show the world that vacuum-tube machines were indeed expensive but entirely feasible.

The start of World War II had immediate consequences for Zuse; he was called to serve in the army, and was for six months deployed on the Eastern front. With the help of Kurt Pannke, Zuse tried to obtain a transfer to Berlin in order to continue his work on the next computing machine. Helmut Schreyer, who worked as an engineer at the university, also tried to obtain Zuse’s discharge by offering to build the military an automatic air-defense machine that could be operational in two years. His offer was met with the sardonic reply that the war would be over by then. Finally Zuse’s previous superiors at Henschel were able to obtain his transfer to the Henschel airplane factory in Berlin-Adlershof, where he was hired to make the calculations necessary to correct the wings of the “flying bombs” (now called cruise missiles) being built in Berlin.

In 1940 Zuse started working for the Special Section F at the Henschel factory. During the next five years he developed the machines S1 and S2. The latter could automatically measure some parameters of missile wings, transform the analog measurement into a digital number, and compute a correction to the wing based on these values. The earlier model, the S1, needed such numbers to be typed on a decimal keyboard. The S1 and S2 were probably the first digital computing machines used for factory process control. The measurement instrument used in the S2 was also almost certainly the first industrial analog-to-digital converter, although it was never used in real production. Both machines were, from the computational point of view, subsets of the machines described below. Their existence remained unknown to the public at large for many years after the war.

In 1940 Zuse put together the machine Z2, an experimental model that used an integer processor built out of relays and a mechanical memory cannibalized from the Z1. This machine helped Zuse convince the German Airspace Research Office (DLV in German) to partially finance the development of the successor to the Z1, the Z3, which would be built using only relays. The Z3 became operational in 1941. It had the same logical design of the Z1 but was built with electrical telephone relays.

Structure and Capabilities of the Z1 and Z3. The Z1 and Z3 worked with floating-point numbers (that is, numbers such as, for example, +12.654 with an integer and a fractional part). Zuse developed an internal numerical representation that strongly resembles the internal number format used in modern computers. Each number was stored separated in three parts: the sign of the number, the exponent of the number in twos complement notation, and the mantissa of the number. In order to handle each part, the processor of the Z1 and Z3 consisted of two main blocks, one for processing the exponents of numbers and one for processing the mantissas.

The two machines, Z1 and Z3, shared a common architecture. Their main components were:

  1. the memory for storing numbers (sixty-four in total);
  2. the processor for computing;
  3. A punched tape for storing the sequence of program instructions; and
  4. an input-output console.

The instructions were read from the tape and were executed one by one by the processor. The console allowed the user to enter decimal numbers with a decimal keyboard (similar to the keyboard of a cash register) while the results were shown in a panel with digits illuminated by lamps.

The instruction set of the Z1 and Z3 consisted of the four arithmetical operations (addition, subtraction, multiplication, and division) as well as the square root operation. There were four additional operations for reading and displaying results and for moving numbers between processor and memory. The Z3 was very much like an early electronic calculator of the 1970s but much slower; a multiplication required eighteen machine cycles and was executed in three seconds.

Using the instruction set mentioned above, it was possible to process any arithmetical formula of the kind used in engineering applications. However, the instruction set did not provide a conditional branching instruction, so that it was relatively difficult, although not unfeasible, to perform more complex computations. Also, the two ends of the punched tape could be bound to form a loop, so that repeated execution of the same program was possible.

Zuse avoided the use of an excessive number of logical gates for the processor by relying on control units that worked as microsequencers, one for each command in the instruction set. A microsequencer consisted of a rotating arm that advanced one step in each cycle of the machine like a rotary dial. A clock (a rotating motor) provided the clock cycles needed to synchronize the machine. In the case of the Z3, the operating frequency was set at five cycles per second. Five times per second the rotating arm in a microsequencer activated the next step of the operation at hand. For example, in the case of multiplication, repeated addition and shifting of numbers were needed (as happens when two numbers are multiplied by hand). The eighteen partial operations needed were all started by a microsequencer with eighteen contacts for the rotary dial. The microsequencer can thus be thought of as a kind of hardwired program that reduced very complex instructions to a sequence of simple operations. Therefore, modifying the complete internal operation of the machine consisted only of rewiring the microsequencers without having to modify the rest of the processor. This resulted in a very efficient and flexible architecture, explaining how Konrad Zuse was able to build a machine that rivaled the British or American computers built during the same period, even with only a hundredth of the resources at his disposal.

During World War II, Zuse worked continuously for the Henschel factory but was able to start his own business in 1941. The Zuse Ingenieurbüro und Apparatebau, Berlin, was the first company founded with the sole purpose of developing computers. The Z3’s successful demonstration brought Zuse a contract with the German aircraft research unit (DLV) to develop a still larger computer, the Z4. This machine had a very similar design to the Z3 but would have 1,024 memory words instead of only 64. The machine was built and was almost operational by early 1945, when Russian troops approached Berlin.

War’s Aftermath and the Plankalkül. Zuse fled with the Z4 before Berlin fell to the victorious Soviet army. One of his collaborators was able to obtain train transport for the machine, somehow managing to smuggle it as a valuable military asset. The Z1 and Z3 had already been destroyed by air raids during the war, so that the Z4 constituted the only asset of Zuse’s company. After several detours Zuse established himself in Bavaria, where he would survive the following years by painting, consulting, and attempting to restart his company. During this period of forced inactivity, he finished his manuscript on the Plankalkül, a remarkable document first published in the 1970s.

The Plankalkül (calculus of programs) was the first high-level programming language conceived in the world. It was designed by Zuse between 1943 and 1945, that is, at a time when the first computers were being built in the United States, United Kingdom, and Germany. It represents one of the major achievements in the history of ideas in the computer field, although it was first implemented in 1999 by a team of researchers in Berlin.

The Plankalkül corresponded to Zuse’s mature conception of how to build a computer and how to allocate the total computing work to the hardware and software of a machine. Zuse called the first computers he constructed “algebraic machines” in contrast to “logistic machines.” The former were specially built to handle scientific computations while the latter could deal with both scientific and symbolic processing. Zuse’s “logistic machine” was never built, but its design called for a one-bit word memory and a processor that could compute only the basic logic operations (conjunction, disjunction, and negation). It was a minimalistic computer in which the memory consisted of a long chain of bits, which could be grouped in any desired form to represent numbers, characters, arrays, and so on. In some ways the logistic machine resembles Alan Turing’s proposal of 1936, later known as the Turing Machine.

The Plankalkül was the software counterpart of the logistic machine. Complex structures could be built from elementary ones, the simplest being a single bit. Also, sequences of instructions could be grouped into subroutines and functions so that the user dealt only with a powerful high-level instruction set that masked the complexity of the underlying hardware. The Plankalkül heavily exploited the concept of modularity, which later became so important in computer science: Several layers of software made the hardware invisible for the programmer. The hardware itself was to be simple and only able to execute the minimal instruction set.

In Plankalkül the programmer uses variables to perform computations. There are no separate variable declarations: Any variable can be used in any part of the program, and its type is written together with the name. Variable assignment is done as in modern programming languages where a new value overwrites the old value. Many operations are those used in modern programming languages (addition, subtraction, and so on).

Plankalkül is universal. It can deal with conditional instructions of the “if then else” type and makes available an iteration operator W that repeats the execution of a sequence of instructions until a loop-breaking condition is met. Using these constructs, any kind of computation can be coded with Plankalkül.

Although Zuse published some minor papers about the Plankalkül and tried to make it known in Germany, the language fell into oblivion. The main problems were its ambitious scope, the large variety of instructions that it contained, a modular architecture that called for incremental compilation, and the presence of dynamical structures and functionals. Some aspects of the definition were not quite clean, and the absence of type checking would have made it extremely difficult to debug. A practical implementation of the Plankalkül certainly requires a major revision of Zuse’s draft of 1945. However, Plankalkül was very much ahead of its time considering that many of the concepts on which it was based were rediscovered much later. It would take many more years for programming languages to achieve Plankalkül’s level of sophistication.

Rebirth of Zuse’s Company. After World War II, Zuse’s company was revitalized when Professor Eduard Stiefel, from the Technical University of Zurich (ETH), drove to Bavaria to see the refurbished Z4 in operation. He decided to rent the machine for his university. The Z4 was installed in Zurich in 1950, several months before the first UNIVAC was delivered in the United States, and was therefore the first commercial computer in operation in the world. For several years the Z4 was the only computer operating in continental Europe. The machine had the same logical structure as the Z3 but contained more memory and an expanded instruction set. It was used for many years at the ETH and is now part of the history of computing exhibition of Deutsches Museum in Munich. It is the sole Zuse machine built before 1945 that has been preserved.

Zuse’s company (with the new name Zuse KG) flourished after the war, and many other machines were built. They were all numbered progressively (e.g., Z5, Z11) according to their introduction. For some years Zuse continued building relay computers and even argued in favor of micromechanical elements. Gradually, however, the electronic components were miniaturized, their reliability increased, and with the dominance of American companies in this field, Zuse KG had no choice but to develop vacuum-tube and transistor-based machines. The first Zuse KG transistorized computer was the Z23, a commercial success: Eighty machines were delivered in Germany and eighteen to other countries. The German Research Foundation actively promoted the machine and subsidized its introduction in universities, where it was used to jump-start most of the computer science education in universities.

The Z23 and the Z22 (built with vacuum tubes) were remarkable in that they constituted the first radical departure from the architecture of all previous Zuse machines. Their internal structure consisted of serial registers, which allowed the use of fewer components. The number of instructions was kept to a minimum. A compiler allowed programmers to write code with a syntax that was in between assembly code and a high-level programming language. After the Z22 and Z23, Zuse would often confide that the new machines were being designed not by him but by his engineers.

Another important development, and Zuse’s last encore, was the introduction of the Graphomat in 1961, a plotter that could be used by architects and geologists to generate diagrams and drawings. The Graphomat could be connected to the Zuse computers and used gears that provided smooth, continuous movement in each direction. The gears were designed by Zuse himself.

The Z23 and the Graphomat were successful, but the development of the next line of computers proved too costly. Eventually the dominance of the U.S. computer industry in Europe, as well as the late adoption of a fully electronic design, brought financial difficulties to Zuse KG. The company was sold first to Brown Boveri and Company in 1962 and later to Siemens. Production of the Zuse series of computers was eventually stopped. Zuse retired after the Siemens takeover and received retirement benefits. In the ensuing years he continued writing, applying for patents, and making a case for his place in the history of computing.

In retrospect it can be said that Konrad Zuse’s greatest achievement was the development of a family of fully digital, floating-point, programmable machines that were built in almost total intellectual isolation from 1936 to 1945. His dream was to create the small computer for business and scientific applications. He worked single-mindedly during many years to achieve this objective. His 1941 patent application for the computing machine Z3 was refused in 1967 by a German judge as it was deemed to lack “inventiveness.” The decision on the application was delayed so long, firstly, because of the war, and secondly, because a number of major computer companies battled against Zuse in court. Zuse, however, always considered himself the one and true inventor of the computer, and his public statements on this subject demonstrated some bitterness about his lack of recognition in other countries.

Epilogue. Konrad Zuse married Gisela Brandes on 6 January 1945. Gisela gave birth to their first son a few months later, and four more children followed in the ensuing years. But Konrad Zuse was not a family man: Over the years his sole obsession was starting and leading his company. After his retirement he was much decorated in Germany, receiving, among other distinctions, the Federal Cross of Merit and the Siemens Ring. He was named a fellow of the Computer History Museum in California in 1999. Several honorary doctorates, as well as a professorship, were bestowed on him. Furthermore, the most important prize in Germany in the field of computer science bears Konrad Zuse’s name. Zuse died on 18 December 1995, at the age of eighty-five.

His early machines have been reconstructed: A model of the Z1 was built in the 1980s by Zuse himself and is on display at the German Technology Museum in Berlin. The Z3 was reconstructed by Zuse’s engineers in the 1960s and is on display at Deutsches Museum in Munich. A new functional replica of the Z3 was built in Berlin and is on display at the Zuse Museum in Hünfeld, Germany, where several of Zuse KG’s computers are also housed.

It has been frequently said and written that the computer is a by-product of World War II, or at least that its birth was catalyzed by the events surrounding that conflagration. In the case of Konrad Zuse this is only partially true. The inspiration for his first computing machine, the Z1, predates the war. The six months that Zuse spent on the Eastern front in 1939–1940 were certainly an interruption of the project he already had been working on for almost three years. If the war had not started, the Z3 computing machine would have been built sooner. But once hostilities broke out, Zuse at least was able to convince the military establishment that computing machines were useful for aerodynamical numerical calculations. The successful demonstration of the Z2 prototype led to a contract with the German Airspace Research Office (DLV), which financed most of the construction of the Z3. Once the Z3 was operational Zuse built the special-purpose machine S1 and also started building the more powerful computing machine he had being dreaming about all those years, the Z4. The construction of the Z4 was done under a war contract financed by the German military until 1945.

Although almost no one in Germany fully understood the importance of Zuse’s work, at least the people in charge of the strategic management of aeronautic research and development recognized the relevance of fast computations. It is noteworthy that Zuse could leave the Eastern front and be freed of day-to-day responsibilities at the Henschel Werke in order to attend to his own company. This would not have happened if the military experts had not thought that his company was useful and necessary for the war effort.

Konrad Zuse was no resistance hero, but he certainly never tried to gain office or position himself in academic politics. While professors and researchers at German universities, especially at the Technische Hochschule Charlottenburg, flocked to the Nazi party in order to advance in their professions, Zuse’s own career was cut short by the war. Unfortunately, not much is known about his political views at the time. In his memoirs Zuse deals with the regime and politics during the war in just a few paragraphs. Ideologically he was very much impressed by Oswald Spengler’s theory of the decline of Western civilization. He continued to mention Spengler in his late years.

It was probably Konrad Zuse’s personal tragedy that he conceived all the elements of the computer sooner and more elegantly than any other computer pioneer but was living in Germany when the country was on the path to self-destruction. Outside of Germany, and outside a very small circle for that matter, nobody took notice of the Z1, Z2, Z3, and Z4. The S1 and S2 were secret machines. Zuse’s work was not rediscovered until the late 1940s, and by then it was too late for his machines to have had any serious impact on the design and construction of modern computers. Zuse’s work was worth a footnote, at most, in early scholarly books about the history of computing. This has changed since the 1990s, as more has become known about the life and work of this most remarkable computer pioneer.


Konrad Zuse’s notebooks and documents were sold by his widow in 2006 to the Deutsches Museum in Munich, where they are stored in the archives.


Der Plankalkül. Technical Report 63. Bonn: Gesellschaft für Mathematik und Datenverarbeitung, 1972.

Ansätze einer Theorie des Netzautomaten. Leipzig: Barth, 1975.

Petri-Netze aus der Sicht des Ingenieurs. Braunschweig; Wiesbaden: Vieweg, 1980.

The Computer: My Life. Berlin: Springer-Verlag, 1993.


Peters, Arno. Was ist und wie verwirklicht sich: Computer-Sozialismus: Gespräche mit Konrad Zuse. Berlin: Neues Leben, 2000.

Rojas, Raul. “Konrad Zuse’s Legacy: The Architecture of the Z1 and Z3.” IEEE Annals of the History of Computing 19, no. 2 (1997): 5–16.

Raul Rojas

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Early Pioneers

Early Pioneers

The evolution of computer technology between 1930 and 1950 was strongly influenced first by mathematical theoreticians and then by military needs during World War II. During this twenty-year span, the early pioneers of modern computer science found ways to create machines that harnessed the power of electronics, moving beyond strictly mechanical computational devices and laying the foundation for the transistor-based computers that would follow in the 1950s and 1960s.

Conceptual Foundations

In 1931 electrical engineer Vannevar Bush (18901974) designed a mechanical calculator that solved complex differential equations. Although its gears and other moving and stationary parts made the machine difficult to use, Bush's invention was considered significant in mathematical circles because mathematicians and scientists could use it to solve equations long thought to be virtually unsolvable. Bush's greater contribution to modern computer science came in 1945 with the publication of an article that described a conceptual device for linking and accessing information that he called a memex . His device was never built, but the ideas underlying his concept were later influential on the developers of what is now known as hypertext.

In the 1930s, British mathematician and cryptographer Alan Turing (19121954) developed the concept of a mechanical machine by which mathematical statements could be either proved or disproved. Although the Turing Machine was a concept, rather than a device, Turing's principles were part of the foundation upon which early mechanical computational devices were designed. In addition, his work toward speeding up the process of breaking German military codes during World War II was influential in the development of the Colossus (1943), a code-breaking computer that is the first known programmable logic calculator to use electronic valve technology. While the Colossus was significant in the Allied war effort, its influence on the development of computer science was negligible because it was not designed for general purposes and because its existence was considered classified military information until many years after the war had ended.

During the 1940s, the mathematical and theoretical work that would later be incorporated into modern computer technology was overshadowed by focused efforts to create machines designed for specific military purposes. Just as there was a wartime need to increase the code-breaking capabilities of the Allied military forces, there was an urgent need for the accurate creation of artillery firing charts. This was a repetitive task performed by large numbers of people using mechanical computing devices not specifically designed for the purpose. The need to compile these essential military tools more quickly led to government-funded efforts to invent machine solutions to the problem. Scientists in the United States and Great Britain, who had already been studying various means of creating electromechanical computing devices, then turned their energies specifically toward devising one-of-a-kind machines to meet this need.

From Concepts to Machines

The computing devices developed between 1941 and 1951 represent the first generation of modern computer technology, and their inventors are considered the true early pioneers of computer science. The physical implementation of a variety of concepts by men such as Howard H. Aiken, John V. Atanasoff, John Presper Eckert, John W. Mauchly, and German engineer Konrad Zuse set the stage for the business computers built during the 1950s and 1960s.

Howard H. Aiken.

Working in partnership with IBM, Harvard engineer Howard H. Aiken (19001973) produced an electronic calculator for military use in 1944. The machine, which required 804 kilometers (500 miles) of internal wiring, was 15.2 meters (50 feet) tall and 2.44 meters (8 feet) high. It was used by the U.S. Navy to calculate and create ballistics firing charts. The electro-mechanical computer, known as the Harvard Mark I, was controlled by a punched tape paper roll. Its mechanical parts responded to electromagnetic signals. The five-ton machine was slow and time-consuming to program. Its components were vulnerable to damage from the heat generated by the unit. Despite its drawbacks, however, the Harvard Mark I represented a significant point of development in computing technology.

Aiken was a graduate student at Harvard in 1937 when he first conceptualized a machine that would combine and implement the ideas of Charles Babbage (17911871) and Herman Hollerith (18601929). The development of the machine that would be known as the Mark I began in 1939. This electronic relay computer was followed in 1947 by an electronic computer known as the Mark II. Aiken also opened the Harvard Computational Laboratory in 1947, creating the world's first computer science academic program. He later founded a company, Aiken Industries, and continued to influence the development of computer electronics through research and writing.

John V. Atanasoff.

A mathematician at heart and an electrical engineer and theoretic physicist by education, John V. Atanasoff (19031995) began his career teaching mathematics and physics at Iowa State College in 1930. Fascinated by the prospect of finding ways to perform mathematical computations more quickly and accurately, Atanasoff studied the existing machines available for computation, and believed that they could be improved. Categorizing devices such as the Monroe calculator and the IBM tabulator as analog machines, Atanasoff envisioned an electronic, digital device based on base-2 numbers (the binary system).

During the 1930s, Atanasoff worked with graduate student Clifford E. Berry (19181963) to design and build an electronic digital computer that would be introduced in 1939 as the Atanasoff-Berry Computer (ABC). This is widely considered to be the world's first all-electronic digital computing device. Atanasoff filed patent applications for his invention, but the process was slow. Before he could be granted patent protection for his work, and thus historic credit as the creator of the first machine of its kind, patents would be released for the ENIAC as the first electronic digital computer. Atanasoff, who was one of the first computer scientists to understand the potential of digital computing, went on to receive patents for 32 other inventions. Eventually, credit for his best known innovation would revert to him, as well.

J. Presper Eckert, Jr.

In November, 1945, another pivotal computing device was put into use, although its presence was not announced publicly until February 1946. The ENIAC (Electronic Numerical Integrator and Computer) was designed to perform mathematical calculations for military purposes. It began to take shape in 1943 at the Moore School of Electrical Engineering at the University of Pennsylvania, in response to the U.S. Army's need for new ways to produce trajectory tables used for precision targeting of large artillery. As the chief engineer on the ENIAC project, J. Presper Eckert, Jr. (19191995) shared credit for the computer's success with the ENIAC's architect, John W. Mauchly (19071980). Although it was finished too late to contribute to the war effort, the ENIAC was used to design hydrogen bombs, predict weather, and provide calculations related to military-sponsored studies of wind tunnels, thermal ignition , and other phenomena.

The ENIAC was 500 times faster than the Harvard Mark I computer. It cost a few hundred thousand dollars to develop, it weighed 33 metric tons (60,000 pounds), and its dimensions were gargantuan (3.0 meters (10 feet) tall, 0.9 meters (3 feet) deep, 30.5 meters (100 feet) long). Even as the ENIAC was being built, Eckert began working on the problem of creating a stored-program computer, in part because the ENIAC, which had to be rewired for each computational task, proved to be limited by the lack of stored-program capabilities. The result of this next project would be known as the EDVAC (Electronic Discrete Variable Automatic Computer), which was completed in 1951, without the continued involvement of Eckert, who resigned from the Moore School in 1946. Eckert took out patent applications for more than 80 more electronic devices between 1948 and 1966. His pioneering work on the ENIAC and later computer developments earned him many awards, including the U.S. National Medal of Science in 1969.

John W. Mauchly.

The ENIAC computer, from which the modern electronic computer is said to have evolved, was conceived by John W. Mauchly (19071980), a physicist at the Moore School of Electrical Engineering, University of Pennsylvania. Mauchly and chief engineer John Presper Eckert gained notice for their creation of the first general-purpose computer that could perform 5,000 operations per second, a previously unimaginable speed.

During the early part of his career, Mauchly taught at Ursinis College near Philadelphia. After attending an electronics seminar at the Moore School, he ended up joining its staff. The U.S. Army's Ballistics Research Laboratory was familiar with earlier research Mauchly had performed involving the use of motors and vacuum tubes to design and build calculating equipment. In 1943 Mauchly was selected by the military to design a unit capable of writing programs to calculate the trajectories of artillery under multiple conditions. The result was the ENIAC computer, which was completed too late to be of use during World War II.

Although Mauchly and Eckert began collaborating on the EDVAC even as the ENIAC was still being built, they were both forced to resign from the Moore School before the EDVAC was operative due to their desire to be recognized in patent records as inventors of the ENIAC, which breached University of Pennsylvania protocol for patents. Mauchly continued to work with Eckert until 1959, during which time they established the first commercial computer company and built the UNIVAC (Universal Automatic Computer). Despite disputes over patent rights and the origin of certain computer design ideas, Mauchly can rightly be considered a major innovator in the development of practical computing machines designed for flexible use.

British Computer Pioneers

During the years preceding and during World War II, American and British mathematicians and engineers joined forces to support their countries' military efforts, seeking ways to automate such tasks as the compilation of artillery firing tables and the deciphering of enemy coded communications. Much of this work led to the post-war development of electronic computing devices. Manchester University in Manchester, England, was the site of one of these developments, which was known as the Manchester Mark I.

Manchester Mark I.

Following World War II, mathematician Maxwell Newman (18971984) joined Manchester University as professor of pure, rather than applied, mathematics. In 1946 he acquired funding and other resources to build a stored-program computer at the university specifically to investigate its use in the study of pure mathematics. His plan was similar to one being developed at Cambridge University by Maurice V. Wilkes.

At the same time, Freddie C. Williams (19111977), a professor in the electrical engineering department at Manchester University, was investigating the use of cathode ray tubes (CRTs) for program storage. As the work of the Williams team progressed, Newman's team at Manchester encountered difficulties. Ultimately, Newman decided to suspend work on his computer, pending the results of Williams' efforts. By October of 1949, the Williams group had successfully demonstrated an operational version of the Manchester Mark I, a computing machine with true stored program functionality.


At Cambridge University, meanwhile, Maurice V. Wilkes (1913) was working on a project known as EDSAC (Electronic Delay Storage Automatic Calculator). In 1946 he studied electronic computer design at the Moore School of Electrical Engineering at the University of Pennsylvania, the home of ENIAC. Wilkes' research over the next few years resulted in the first operations stored-program computer; the EDSAC was introduced in May of 1949, barely five months before the Manchester Mark I was completed.

Konrad Zuse.

Although American and British mathematicians, physicists, and engineers are credited with many of the innovations in early computer design and manufacturing, German engineer Konrad Zuse (19101995) is also considered one of the early pioneers of modern computer science. By 1941 Zuse had designed and built what became known as the Z3, the world's first electromechanical digital computer controlled by programming. Unlike the British and American efforts that were heavily funded by Allied money, Zuse's work was largely independent of government control or interest.

Between 1936 and 1938, Zuse used recycled parts and donations from friends and family members to assemble his first computer, which he called the Z1. This was the world's first binary computer. It is significant that Zuse's innovations took place outside the mainstream of computer development then going on in other parts of the world. Drafted for military service in 1939, Zuse tried in vain to persuade the Nazi/German Army military establishment of the value of his inventions. When he was reassigned from active duty to work as a structural aircraft engineer, Zuse resumed his computer-building activities, incorporating telephone relays in the construction of the Z2 and electromagnetic relays in the Z3.

Zuse's model Z4 was the only one of his original inventions to survive the bombing of Germany during World War II. By the end of the war, Zuse and his family were refugees in southern Germany. Between 1945 and 1950, Zuse continued his research when it was possible, and in 1947 he jointly founded the Zuse Engineering Company to design and build computers for scientific and business applications. Over the next several decades, Zuse and his company began interacting with computer-development interests worldwide, and his early innovations received the recognition they deserved. He received numerous awards and honors for his contributions to the field of modern computer technology.

Early Computer Programmers

In 1945 the U.S. Army hired eighty mathematicians whose high security, top-secret work no one had performed before. All of them were women. Their job was to program the ENIAC to calculate artillery firing trajectories, in order to increase the accuracy of military war efforts.

As the first wave of computer programmers, these women laid the foundation for all later computer programming. They had to become familiar with the mechanics of the ENIAC and then figure out how to give the computer directions to carry out specific actions. The women, many of whom had recently graduated from college as mathematics majors, were recruited because there was a scarcity of male mathematicians available.

In October of 1998, four of these pioneersJean Kathleen McNulty Mauchly Antonelli, Jennings Bartik, Frances Snyder Holberton, and Marlyn Wescoff Meltzerwere honored by Women in Technology International for their contributions to the computer industry. At the ceremony, Antonelli pointed out that the capabilities of the ENIAC were considered more remarkable during its decade of operation than were the achievements of the women who programmed the machine to perform as it did. Holberton, who compared their wartime work to that of construction engineers, would later be among the programmers who helped develop the programming languages known as COBOL and FORTRAN.

Computer Pioneers, 19301950

As the 1940s drew to a close, the early pioneers of modern computing continued to pursue new avenues of research in the growing field of computer science. Other engineers made new contributions. In 1947 came the invention of the transistor, which replaced vacuum tube technology in the design of computers and revolutionized the computer and electronic communications industries. The inventors of the transistor, John Bardeen (19081991), William Shockley (19101989), and Walter Brattain (19021987), would jointly share the 1956 Nobel Prize in physics. Their 1947 innovation rounded out two decades of pioneering work that took computing from mechanical calculating machines to the brink of the digital age.

see also Computer Scientists; Digital Computing; Early Computers.

Pamela Willwerth Aue


Bellis, Mary. "Presper Eckert and John MauchlyThe ENIAC and UNIVAC Computers." Inventors. <>

"The Birth of Electronic Computers." Early Electronic Computers. <>

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Zuse, Konrad

Konrad Zuse

Konrad Zuse (1910-1995) is considered by many to be one of the founders of modern computing because of his work on early stage computers and computing languages.

Early Life

Konrad Zuse was born in 1910 in Berlin, Germany. His family moved to East Prussia shortly after he was born, and Zuse spent most of his life there. At a young age, Zuse showed talent in the arts and engineering, and went from making block prints and drawings to building model trains and railroads. As a boy he attended school in the town of Braunsberg, and received an education in the liberal arts. At 17, Zuse's interest in engineering led him to apply to the Berlin Technical School, where he studied the various facets of modern technical engineering. While at school, Zuse built a vending machine that dispensed food and drink, took money, and gave back exact change. However, during his studies Zuse was constantly frustrated at the numerous calculations involved in the processes of engineering. All of these calculations had to be written out and solved by hand.

Inspired to Create a Computing Machine

Zuse soon got a job at the Henschel Aircraft Company as an engineer, supervising the building of aircraft. One of his jobs was to inspect the wings of the plane, and see how much stress could be placed upon them before they would start to break apart. This job required many and diverse calculations that took up a lot of time. It was frustrating work, and Zuse spent many hours with his calculator and a pen. This inspired him to come up with the idea of a machine that would simplify the work involved in calculating advanced mathematics. However, building such a machine would not be simple. Zuse realized that he had to figure out a way for his machine to record and save the various steps involved in doing complex calculations. This required the calculation machine to be able to recognize and store various stages of the mathematical problem.

The Z1 computing machine

Zuse left his job at the aircraft company, and started to work on his invention. Using his parents' living room as a laboratory, he first figured out what his ideal machine would need. He envisioned an input device where he could define the various parts of the problem, a storage device for saving the various stages of the problem, and an arithmetical module that would work out all the steps of the equation. He would also need some way to link the various parts of the machine together, so they could operate as one. Zuse also planned to add a mechanical keyboard to his device, so he could input the various mathematical problems more efficiently.

With these ideas in mind, Zuse started to work on his project. He was a competent mechanic and draftsman, but his knowledge did not extend into the realm of electrical engineering, a discipline that would have helped him build the machine that he had envisioned. However, this did not dissuade him. Zuse was infinitely more familiar with the two-digit number system of binary arithmetic than he was with the 10-digit number system used by most calculating machines of the time, so Zuse decided that he would program his computing machine to run using binary code. It would be simpler to make a system dependent on only two numbers rather than to keep track of ten. Also, since anything could be expressed through binary code, this would give his machine greater versatility in figuring out complex equations. Zuse's final product consisted of a memory mechanism designed around moving pins in and out of slots, to represent zero or one. Another hidden benefit, Zuse realized, was that because his computing machine was only dealing with two digits, he could keep the space he needed to a minimum, and the resulting machine was very compact. The memory unit that he created took up about a cubic meter of space. Connected to a calculation unit, Zuse's first computing machine, the ZI, was completed around 1938.

Improvements Made to Computing Machines

Shortly after Zuse completed his first computing machine, one of his friends, Helmut Schreyer, who was also an electric engineer, suggested that Zuse replace the mechanical workings of his computing machine with vacuum tubes and telephone relay switches, to speed up the processing time and increase the efficiency of the machine. Zuse rejected the idea of using vacuum tubes, but he did incorporate the relay switches into his designs.

Zuse created the Z2 computing machine using the relay switches suggested by Schreyer. Built with the telephone relays, it was a bit more unstable than the older mechanical system, because the switches were not always reliable. However, by accommodating these new ideas, Zuse was stepping far ahead of his time, anticipating a future techology.

Zuse's work with these new forms of computation attracted the attention of the German Experimental Aircraft Institute. They had been working unsuccessfully to reduce the number of planes that broke apart during flight because of wear and tear at the wings. The Institute's job was to figure out how to overcome this problem, called fluttering. However, the Institute was not equipped to handle the vast number of calculations required to correct the problem. Zuse was contacted, and a deal was worked out where the Institute would give Zuse funding to build a better computing machine, while at the same time he assisted the Institute in building more wind-resistant planes. Zuse received the grant from the Institute and began working on the Z3, while still using his parents' living room as a base of operations. When it was finished, the Z3 could add, subtract, multiply, divide, and extract a square root. This could be done in a matter of seconds, since the number of relays that Zuse had been able to incorporate was much greater than his previous computing machines.


Zuse's computing machines were ahead of their time in both size and portability. Zuse's Z3 took up only a closet's worth of space, and could be moved around at will. Zuse had also invented a push button control panel that allowed the user to input various commands. The device recognized conversion, and could convert decimal numbers into binary numbers and back again at the user's command.

Zuse was also the first person to come up with a programming language for his systems. He incorporated two unique symbols, which are used all the time today in mathematical calculations. They are greater than or equal to (≥) and less than or equal to (≤). Zuse was a technological pioneer even before such terms as hardware or software were commonplace.

World War II

Zuse was recruited by the Third Reich to create computing machines for their forces during World War II. His third computing machine, the Z3, was destroyed when an Allied bomb fell on the house where Zuse and his family lived. Zuse survived, however, and went on to create another computing machine called the S1, similar to the Z3 except that it was not programmable. The S1 computing machines were used to guide unmanned German gliders that carried bombs to targets. These gliders were directed to their targets via remote control, and used the S1 system designed by Zuse to adjust their wings and tail to flying conditions and to the movement of the intended target.

Near the end of the war, Zuse created the Z4, his most advanced system to date. Because his machine was portable, he was able to move it and keep the Allies from discovering and destroying it. He hid the computing machine in a University town by the name of Gottingen, and left it with the Experimental Aircraft Institute, the same institution that he had worked for during the War. His devices were not discovered until much later, when French troops discovered the hidden Z4.

After the French found his machine, word of the new technology spread throughout France and the United States. Members of the scientific community marveled at his computing machine, and they were amazed at how much he had accomplished without any knowledge of similar projects that were being developed at the same time.

Zuse's Later Life

After the war Zuse continued to experiment with computational devices. It took him a long time to release the information about his machines, because even after the war was over he distrusted the Allies and refused to answer their questions about his methods and computing machines.

Zuse soon learned about American scientists that had worked on technological developments during the War. Although the Americans had produced systems that were much larger than Zuse's had been, it was Zuse who brought the science of computing further than anyone had thought possible. He continued designing, and formed his own company, Zuse KG, that continued developing scientific computing systems.

Zuse is still thought to be the true father of modern computing, because of the advanced nature of his inventions.


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Zuse, Konrad

Zuse, Konrad

German Engineer

Konrad Zuse was a German engineer who designed and built a binary computer during the 1930s. He is thought to have created the first functioning program-controlled computer, however his earliest efforts were destroyed during World War II. By the end of his life, Zuse had received many honors for his contributions to the development of the computer, and he was recognized as one of the pioneers of electromechanical computing.

Zuse was born in Berlin, Germany, in 1910. During his youth he showed talent in art and engineering. As an artist, he created block prints, drawings, and cartoons; as an engineer, he built mechanical devices such as grab cranes and model train rail networks. He graduated from high school at the age of sixteen and entered the Technical University of Berlin, having made the decision to study civil engineering. While he was a university student, he built a vending machine that delivered selected items, accepted money, and returned change.

Zuse completed his degree in 1935 and worked for a brief time as a structural engineer for the Henschel Aircraft Company. He left this position to work independently on building a computer. His parents' living room served as his laboratory, his assistants were unpaid college friends, and his funding was raised from friends and family members. His goal was to create a mechanical calculating machine based on a binary system rather than on the decimal system used in calculators. The machine would consist of a memory unit and an arithmetic unit, and it would be programmable.

Zuse's Z1 computer was operational by 1938. Helmut Schreyer, a friend and electronic engineer, suggested replacing the mechanical relay system with vacuum tubes and telephone relay switches to shorten the processing time. Zuse rejected the vacuum tube idea but considered using the telephone relay switches. The design of the Z2 incorporated this idea.

In 1939 Adolf Hitler and the Nazis invaded Poland, beginning World War II. The war interrupted Zuse's work and he was soon drafted into the German army. To no avail, both Zuse and Schreyer tried to interest the German military in the computer project. However, Zuse was transferred from active duty to work as a structural engineer for Henschel Aircraft. His assignment was related to the development of unmanned flying bombs, or cruise missiles. This transfer allowed him time to complete construction of the Z2, which used telephone relays for the arithmetic unit. In 1940 Zuse successfully demonstrated the Z2 to the German Aeronautics Research Institute or DLV.

As a result, he received partial funding for the next generation model, the Z3, which was constructed from recycled materials. Once again he relied on the support of family and friends. The telephone relays were used equipment rescued by associates who worked for the state telephone and postal system. The Z3 used electromagnetic relays for the memory and arithmetic units, was based on a binary number system, and was programmable. Discarded film strips were used in place of punched cards for input. The Z3 was destroyed during a bombing raid over Berlin.

Construction of the Z4 began in 1942. This model was moved from Berlin to southern Germany when the Allied bombing became intense. At the end of the war in 1945, Zuse, his family, and the Z4 were refugees in Hinterstein, a small alpine village in southern Germany. For the next two years Zuse worked on theoretical problems, developing Plankalkül, an algorithmic language, and formalizing the game of chess. To support his family, he painted and sold alpine scenes to vacationing American troops.

In 1947 Zuse and Harro Stucken, an engineer from the Henschel Aircraft Company, founded Zuse Engineering Company to build computers for science and industry. Later the company became ZUSE KG. The company contracted with Remington Rand to build punched card devices. In 1950 the company leased the Z4 to the Swiss Federal Institute of Technology, where it remained in use until 1955. The company's first German contract was with Leitz Camera to build computers to determine lens specifications.

As the company grew, Zuse began to receive honorary degrees and awards for his work. In 1962 Howard H. Aiken, who designed the MARK I computer (the first American-built programmable computing system) acknowledged Zuse's claim to being one of the first to build a program-controlled computer. During this time a copy of model Z3 was built for display in the German Museum. By the late 1960s the company had been sold to Seimans, and Zuse turned his attention to other areas. He continued to work on problems related to computers and developed a prototype for a CAD, or computer-aided design, machine.

The claim that Zuse built the first computer will remain unresolved, due in part to the destruction of both the Z1 and the Z3 computers in wartime bombings. What is clear, however, is that he developed his machines without knowledge of or interaction with others in the field, without proper funding, and using scavenged materials while always in danger from the war. At the time of his death in 1995, he had gained recognition for his contribution to computer science.

see also Early Computers; Early Pioneers.

Bertha Kugelman Morimoto


Zuse, Konrad. The Computer: My Life. Berlin and Heidelberg: Springer-Verlag, 1993.

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