At the beginning of WW2 in Berlin, Germany, Konrad Zuse was a construction engineer for the Henschel Aircraft Company who built a series of automatic calculators to assist him in his engineering work. Zuse's inventions have earned the title of being "The Inventor Of The Modern Computer." Zuse modestly dismissed the title, while praising many of the inventions of his contemporaries and successors, as being equally, if not more important than his.

Zuse learned that one of the most difficult aspects of doing a large calculation is keeping track of all intermediate results and using them, in their proper place, in later steps of the calculation, Zuse realized that an automatic-calculator device would require three basic elements a memory, a control, and a calculator for the arithmetic.

After Zuse constructed his first three digital computers during the war, he was unable to convince the Nazi government to support his work, for a computer based on electronic valves, the proposal was rejected on the grounds that the Germans were so close to winning the War that further research effort was not necessary. Zuse left for Zurich to finish his work, and later moved to the United States, where he formed his own company for the marketing and construction of his designs.

Konrad Zuse's Z1 Circa 1938
Among Zuse's Achievements

In 1936, a mechanical only calculator/binary computer called the Z1, made for the express purpose of speeding with his lengthy engineering calculations. The Z1 was Zuse's test model, he used it to discover several, ground-breaking, technologies, in calculator development: on the software side there was program control, using the binary system of numbers, a high-capacity memory, and modules or relays operating on the yes/no principle. Not all of his ideas were fully used in the Z1, Zuse succeeded more with each prototype, but he had his ideas early.

Zuse completed the first, fully functioning, electro-mechanical computer, which was able to complete his design for using relay type operations, called the Z2, in 1939.

The Z3 was the first, fully programmable, electronic, computer. The Z3 was based on relays and was very advanced for its time, it utilized the binary number system and could handle floating-point arithmetic. During the war, paper was in short supply in Germany, so instead of using paper, tape, and/or punched cards, Zuse used old movie film to store his programs and data with the Z3.

"Plankalkül", the first algorithmic programming language was developed by Zuse, in 1946, with which he wrote a chess program. The "Plankalkül" included arrays and records, and used a style of assignment in which the new value appears on the right. An array is a collection of identically typed, data items, distinguished by their indices or "subscripts" where A is the array name and i, j and k are the indices. Arrays are appropriate for storing data, which are best when accessed sequentially.

Finally the Z4 escaped being nearly destroyed, like the Z1 thru Z3, by being smuggled from Germany in a horse drawn cart and hidden in stables on route to Zurich, Switzerland, where Zuse completed and installed the Z4 in the Applied Mathematics Division of Zurich's Federal Polytechnical Institute, where it was used until 1955. It had a capacity of 1,024 words with a mechanical memory, several card readers and punches, and various facilities to enable flexible programming.