Konrad Zuse and the Invention of the Modern Computer

The First Freely Programmable Computer was invented by Konrad Zuse

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Bellis, Mary. "Konrad Zuse and the Invention of the Modern Computer." ThoughtCo, Jul. 31, 2017, thoughtco.com/konrad-zuse-modern-computer-4078237. Bellis, Mary. (2017, July 31). Konrad Zuse and the Invention of the Modern Computer. Retrieved from https://www.thoughtco.com/konrad-zuse-modern-computer-4078237 Bellis, Mary. "Konrad Zuse and the Invention of the Modern Computer." ThoughtCo. https://www.thoughtco.com/konrad-zuse-modern-computer-4078237 (accessed October 23, 2017).
Zuse Z1 replica in the German Museum of Technology in Berlin. Creative Commons/ComputerGeek

Konrad Zuse was a construction engineer for the Henschel Aircraft Company in Berlin, Germany at the beginning of World War II. Zuse earned the semi-official title of "inventor of the modern computer" for his series of automatic calculators, which he invented to help him with his lengthy engineering calculations. Zuse modestly dismissed the title, though, praising the inventions of his contemporaries and successors as being equally – if not more – important than his own.

The Z1 Calculator 

One of the most difficult aspects of performing large calculations with slide rules or mechanical adding machines is keeping track of all the intermediate results and using them in their proper place in the later steps of the calculation. Zuse wanted to overcome that difficulty. He realized that an automatic calculator would require three basic elements: a control, a memory and a calculator for the arithmetic.

So Zuse made a mechanical calculator called the “Z1” in 1936. This was the first binary computer. He used it to explore several groundbreaking technologies in calculator development: floating-point arithmetic, high-capacity memory and modules or relays operating on the yes/no principle. 

The World’s First Electronic, Full Programmable Digital Computers

Zuse's ideas were not fully implemented in the Z1 but they succeeded more with each Z prototype. Zuse completed the Z2, the first fully functioning electro-mechanical computer in 1939, and the Z3 in 1941.

The Z3 used recycled materials donated by fellow university staff and students. It was the world's first electronic, fully programmable digital computer based on a binary floating-point number and a switching system. Zuse used old movie film to store his programs and data for the Z3 instead of paper tape or punched cards.

Paper was in short supply in Germany during the war.

According to "The Life and Work of Konrad Zuse" by Horst Zuse:

"In 1941, the Z3 contained almost all the features of a modern computer as defined by John von Neumann and his colleagues in 1946. The only exception was the ability to store the program in the memory together with the data. Konrad Zuse did not implement this feature in the Z3 because his 64-word memory was too small to support this mode of operation. Due to the fact that he wanted to calculate thousands of instructions in a meaningful order, he only used the memory to store values or numbers.

The block structure of the Z3 is very similar to a modern computer. The Z3 consisted of separate units, such as a punch tape reader, control unit, floating-point arithmetic unit, and input/output devices.”

The First Algorithmic Programming Language

Zuse wrote the first algorithmic programming language in 1946. He called it 'Plankalkül' and used it to program his computers. He wrote the world's first chess-playing program using Plankalkül.

The Plankalkül language included arrays and records and used a style of assignment – storing the value of an expression in a variable -- in which the new value appears in the right column.

An array is a collection of identically typed data items distinguished by their indices or "subscripts,” such as A[i,j,k], in which A is the array name and ​i, j and k are the indices. Arrays are best when accessed in an unpredictable order. This is in contrast to lists, which are best when accessed sequentially.

The Effect of World War II

Zuse was unable to convince the Nazi government to support his work for a computer based on electronic valves. The Germans thought they were close to winning the war and felt no need to support further research.

The Z1 through Z3 models were shuttered, along with Zuse Apparatebau, the first computer company that Zuse formed in 1940. Zuse left for Zurich to finish his work on the Z4, which he smuggled from Germany in a military truck by hiding it in stables en route to Switzerland.

He completed and installed the Z4 in the Applied Mathematics Division of Zurich's Federal Polytechnical Institute and it remained in use there until 1955. 

The Z4 had a mechanical memory with a capacity of 1,024 words and several card readers. Zuse no longer had to use movie film to store programs since he could now use punch cards. The Z4 had punches and various facilities to enable flexible programming, including address translation and conditional branching. 

Zuse moved back to Germany in 1949 to form a second company called Zuse KG for the construction and marketing of his designs. Zuse rebuilt models of the Z3 in 1960 and the Z1 in 1984. He died in 1995 in Germany.