Konrad Zuse (1910  1995)
Before George Stibitz began fiddling with old tin cans and batteries in 1938, or Claude Shannon wrote his masters thesis, Konrad Zuse was already labouring away in the cramped living room of his parent's Berlin apartment.
Zuse knew little of Bush's Differential Analyser, was almost completely unaware of Babbage's Analytical Engine theories, and had never heard of George Boole, and yet he set out to develop a generalpurpose computer, designed to operate on boolean principles.
It seemed the time had simply come.
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A civil engineering student at Technische Hochschule in 1934, Zuse  much like Shannon and Stibitz  soon became weary of the long hours of boring linear calculations that went with the job. There had to be a better way, he decided.
This was the 20th century, there ought to be a machine that could take over the tedious calculations, that could perform any mathematical computation he needed, no matter how complex or convoluted.
There wasn't, so Zuse set out to build one.
In 1936, Zuse threw in his job with the Henschel Aircraft Company and, backed by a little money from trusting friends, set up a table in his parent's living room and went to work. Two years later a complicated labyrinth of circuits and relays lay spread around the room.
(His mother's reaction to this sprawling work of genius has, unfortunately, been lost to us.)
The V1 (later renamed the Z1 to distinguish his inventions from the V1 and V2 guided missiles designed by his friend Werner von Braun) was a cumbersome combination of steel plates and pins, but it achieved what Zuse had set out to do  it was a general (rather than built for a single, specific purpose) calculating machine
The Z1 worked on the binary two digit system, making it both easier to construct and faster to use. It also had a mechanical memory, capable of storing 16 24bit binary numbers.
The Z1 was ‘programmed’ by a series of holes punched into 35millimetre film and fed through the machine  not unlike the pattern cards devised by Ada Byron  while data was input through a basic fourdecimalplace keyboard. A board of light bulbs displayed the calculation results.
It worked, but it was clumsy and far from reliable.
Zuse decided to incorporate the mechanical memory of the Z1 in his next machine, but to replace mechanical signal routing devices with a relaybased unit. The Z2 functioned well enough, but still required constant diligence to ensure its computations were correct.
And so he moved on.
For his Z3, Zuse solved the problems of sparking relays with a revolving, coated drum and carbon brushes. The new machine included a 64word memory and could perform all the basic addition, subtraction, multiplication, and division exercises, as well as calculate square roots and multiply by negative numbers. It's speed was comparable with the Harvard Mark I, but the Z3 was the more flexible machine.
The Z3 was completed by the end of 1941, only to be destroyed by an air raid in 1944.
Never a man to give up easily, Zuse continued to work on his Z4 (essentially the same machine as the Z3, but with an increased memory of 32 bits), moving the machine all over the city to avoid the devastation of the Berlin blitz and discovery by allied troops.
While Zuse was captured and interrogated by the allies, the Z4 remained safe. Renamed  somewhat unimaginatively  the Ziffernrechner (number calculator), the Z4 found a home in Zurich in 1950, installed at the Federal Polytechnical Institute.
There it stayed until 1955 when it was moved to the French Aerodynamic Research Institution, near Basel, where it continued to churn out calculations for another 5 years.
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Following the end of World War Two, it took Zuse some time to be able to return to his work.
Finally, in 1949, Zuse founded the first German computer company  Zuse KG  with 5 employees working out of an old post relay station in the tiny village of Neukirchen.
By 1961, Zuse had started development on his Z25, a machine planned to be both smaller and less expensive than its predecessors.
The first four Z25's were delivered by 1964, but the company ran into financial trouble and spent the next few years being passed among various owners. In 1969, the latest owner  Siemens AG  scrapped the Zuse KG logo and Konrad Zuse left the company.
By the time Zuse left, 102 Z25's had been delivered.
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In 1992, Zuse returned to his mechanical engineering roots and began to plan his final project  the Helix Tower, a kind of technowindmill for the production of electricity.
The project was never finished and Zuse died 3 years later.
Related:
Binary  So Simple a Computer Can Do It
What's So Logical About Boolean Algebra?
