Konrad Zuse

German computer engineer

• Born: June 22, 1910
• Birthplace: Berlin, Germany
• Died: December 18, 1995
• Place of death: Hünfeld, Germany

Zuse designed and built early computers, including the Z3, the world’s first general-purpose, program-controlled, reliable computer. He also wrote the first book about digital physics.

Primary fields: Computer science; physics

Primary invention: Z3 programmable computer

Early Life

Born in Berlin, Germany, to Emil and Maria Zuse, Konrad Zuse (KAHN-raht TSEW-zuh) showed high intelligence as a boy. Much later, he wrote that he thought visually and therefore showed little interest in music and in the once popular hobby of building radios. He did, however, exercise a genuine talent in drawing and painting.

Soon after he passed an examination in 1928, Zuse enrolled in the Technische Hochschule in Berlin-Charlottenburg, where he finally majored in civil engineering. Meanwhile, besides participating in stage plays, he kept active intellectually in ways beyond what his formal studies strictly required. He designed, for instance, a futuristic city, and he gave serious thought to self-replicating machinery in outer space.

In addition, Zuse thought about how he could avoid the tedium and risk of error in the calculations that engineering required. His experience had taught him that a burdensome task in big calculations was recording intermediate answers correctly and later using them appropriately. Whether he worked with a mechanical adding machine or a slide rule, he still faced that task. To handle intermediate answers with less trouble, Zuse printed boxes on paper. Numbers in boxes together in a horizontal row would be multiplied together, and numbers in boxes together in a vertical column would be added together. The idea of the printed boxes led Zuse to his idea that he could use the patterns indicated on the paper forms to join mechanical calculators to solve complex problems. From that idea, he realized by 1934 that a machine that could calculate automatically needed only three main parts: one each for arithmetic, memory, and control.

Receiving his university degree in 1935, Zuse began work as a structural engineer for the Henschel aircraft company but soon, to his parents’ dismay, quit to concentrate on building a computer. As his workplace, he chose his parents’ Berlin apartment, especially the living room, and received financial help from his family and several of his friends.

Life’s Work

Working at home with friends as his assistants, Zuse planned and constructed several computers that he designated by the letter V and by a numeral to indicate the particular model. His first computer was therefore the V1, for Versuchsmodell 1 (experimental model 1). It was not until after World War II that he replaced the V in each of his model names with a Z, to avoid confusion with the famous V-1 and V-2 rockets, which were Vergeltungswaffen (retaliatory weapons). From the time of the change of designating letters, Zuse usually referred to his early computers by using a Z.

Not being an expert on the mechanical calculators of the 1930’s, Zuse relied on his own thinking for the Z1 and thus decided not on the commonly used decimal system, with wheels of ten positions each, but on a binary system (in which there are only two digits, 0 and 1). In 1936, when Zuse applied for a patent in Germany, he was also unfamiliar with the work of Charles Babbage, the nineteenth century British pioneer in computer science, and with the monumental paper “On Computable Numbers,” which the British mathematicianAlan Mathison Turing submitted that year for publication.

Actually finished in 1938, the Z1 was almost all mechanical. It worked, but not well. The trouble lay in the two arithmetic units, the one for the 16-bit significand and the other for the 7-bit exponent. As Zuse realized, the complexity of the arrangement of gears and levers needed for transmitting signals led to failures. Knowing that, in contrast, electric wires could easily carry signals around corners, Zuse started planning the Z2 before he and his coworkers had finished the Z1.

Although his friend Helmut Schreyer actually built a model section of the Z2 with vacuum tubes, Zuse intended to use electromechanical relays instead, because he could more easily visualize how they worked and because they were easier to acquire. Needing thousands of relays, Zuse, Schreyer, and others rebuilt previously used ones. In 1939, when Zuse had almost finished the Z2, the German army drafted him. He spent months as a soldier before friends managed to have him released to civilian duty. Even so, that duty was to work again for the Henschel aircraft company. Zuse had to complete the Z2 in his spare time.

The Z2 had the same mechanical memory as the Z1, but its control and arithmetic units used relays. When Zuse finished this improved computer, he demonstrated it for the German Aeronautical Research Institute. The researchers who saw the Z2 at work realized that it was too unreliable for practical use, but they were impressed enough to offer Zuse money to pay for his work on his next computer, the Z3.

The money Zuse received did not, however, pay for conventional laboratory space, so he and his friends continued their living-room work as the Z3 took shape from 1939 until December 5, 1941, when it was finished. It worked well within its built-in limitation of a tiny memory, but that limitation led the German Aeronautical Research Institute to decide that the usual methods were better for solving the systems of linear equations on which it had planned to use the Z3. Zuse therefore had to store his computer in his parents’ apartment, where Allied bombing of Berlin destroyed the machine in 1944.

Soon after he had finished the Z3, Zuse was working on the Z4, despite serving briefly again as a soldier before he was released once more to return to his official job with Henschel. During the building of the Z4, Zuse changed the location of his laboratory, but he had to endure the hardships of working in Germany when World War II had turned against his homeland. Amid wartime deprivation, on January 6, 1945, he married Gisela Brandes. Then, as the Soviets advanced toward Berlin, he and his associates laboriously moved the massive Z4 to the Experimental Aerodynamics Institute in Göttingen. It was not long, however, before Zuse had to arrange again to move the Z4, this time because of the threat of the Western Allies. Eventually, Zuse hid the Z4 in a cellar at the Bavarian village of Hinterstein, where it remained after the German surrender until Zuse and others moved it to a stable in the town of Hopferau. Yet, after Zuse cleaned and repaired the Z4, it worked just as he had thought it would, and in 1950 it found a home at the Swiss Federal Institute of Technology. At that time the only computer working on the European mainland, it now rests in the German Museum at Munich.

Meanwhile, shortly after the war’s end, Zuse turned his attention to a computer language, the Plankalkül (plan calculus), on which he had started work in the 1930’s. He finished his manuscript in 1946, but the circumstances of life in his homeland made publication difficult then. It was not until 1972 that Zuse’s ideas about what he considered the initial algorithmic language reached print. Unfortunately for Zuse, by 1972 other computer languages had become so popular that few programmers used the Plankalkül.

Nevertheless, Zuse enjoyed success for years in postwar Europe as a founder of the computer-manufacturing company Zuse KG. Because, however, he had to spend most of his time as a businessman, not an inventor, he felt relief, along with failure, when debt led to corporate changes and he became merely a consultant after his own company in 1967 became part of Siemens AG.

With more time for his artistic and scientific passions, Zuse painted numerous pictures and, developing an idea from his youth, wrote Rechnender Raum (1969; calculating space), the seminal book on digital physics, in which he presented his theory that discrete laws govern the physical universe. The universe, he said, is the output of a computation on a cellular automaton; in other words, an enormous grid of cells, acting as a network of computers working in parallel, has determined everything that is or will be. Whether or not such is the case, Zuse died in Hünfeld on December 18, 1995, when he was eighty-five years old.

Impact

By the time he died, Zuse had received several honorary doctorates and other awards, including the Computer Pioneer Award of the Institute of Electrical and Electronics Engineers and the first Konrad Zuse Medal. Working in wartime Germany with almost no knowledge of what inventors in the United States and Great Britain were doing in his field and, for that matter, no knowledge of what work Germans beyond his team were doing, he designed and, with his associates, built the Z3, the first successful computer controlled by a program and used for general calculation. In computer science, he developed an early algorithmic language. Extending his thoughts to cosmology, he presented an idea that, while it remains unproven, has prompted discussions and stirred imaginations.

In The Computer—My Life (1993), Zuse implied that he did not receive the recognition he deserved as a founder of computer science and engineering. His years spent as a business executive contributed to his scientific obscurity relative to his accomplishments, as did his isolation in Germany in the years just before, during, and even just after World War II. Furthermore, his slowness in turning to electronic components put him behind a number of other pioneers. It may be true that the line of development of computers in English-speaking countries does not pass through Zuse’s work on the Z3 or the Plankalkül, but Zuse deserves credit for what he did before anyone else had done it.

Bibliography

Essinger, James. Jacquard’s Web: How a Hand-Loom Led to the Birth of the Information Age. New York: Oxford University Press, 2004. A story of the modern computer as a development from Joseph-Marie Jacquard’s silk-weaving loom and Charles Babbage’s difference engine. Zuse’s work is briefly mentioned. Illustrations, bibliography, index.

Williams, Michael R. A History of Computing Technology. 2d ed. Los Alamitos, Calif.: IEEE Computer Society Press, 1997. A thorough study that devotes a long section to Zuse’s work as a founder of modern computer engineering and gives details about various machines that he designed and built. Illustrations, bibliography, index.

Wolfram, Stephen. A New Kind of Science. Champaign, Ill.: Wolfram Media, 2002. A long, controversial study of computational systems that presents the universe as computable but that, according to detractors, gives inadequate credit to Wolfram’s predecessor Zuse. Illustrations, index.

Zuse, Konrad. The Computer—My Life. Translated by Patricia McKenna and J. Andrew Ross. New York: Springer-Verlag, 1993. An autobiography in which the author concentrates on his work and presents his case for deserving prominence in the history of computer science and engineering. Illustrations, bibliography, indexes.