The Survivor

Somehow Zuse found time to build other computers as well. The S1 was a non-programmable machine using hard-wired programs. It served in the design of the Henschel flying bomb HS-293, a pilotless aircraft guided by radio from a bomber. It replaced a dozen calculators. An improved design, the S2, was too late for routine service and is the one that Zuse thinks might have been captured by the Russian army. But the big one was the Z4: a full-sized general-purpose computer, the only one to survive the war.

Construction of the Z4 began in 1943, even before the Z3 was finished. For this large machine Zuse returned to his successful mechanical memory design. Whilst this now seems a retrograde step it was the only way he could achieve a large memory (1024 32-bit words) in a reasonable volume.

Work on the computer began in Ber­lin but Allied bombing posed an everpresent threat⁷. "My workshop was damaged several times, and three times during the war we had to move the Z4 around Berlin." As allied bombing increased in 1945, the authorities de­cided to move Zuse and his new compu­ter out of the capital to Göttingen, 160 miles to the west. There construction was completed and on April 28, 1945, demonstration programs were run for the authorities. "This was the moment for which I had waited for 10 years–when my work finally brought the suc­cess I desired." The irony for Zuse was that the machine was immediately dis­mantled, because the American army was by then just a few miles away.

The odyssey continued as they were ordered to underground works in the Harz mountains where the V1 and V2 weapons were being built. Zuse has described the conditions there as terrible. "We refused to leave the machine there." With great difficulty it was moved to an alpine village just north of the Austrian border where it was set up in a barn. There it stayed until 1949 when it was rescued, rebuilt and estab­lished in the Technical University in Zürich in 1950. For a time it was the only functional digital computer on the continent.

After the War

Zuse continued to develop his ideas for computers and planned what was prob­ably the first algorithmic computer lan­guage. The game of chess served as a test subject.

In 1949 he re-established his own firm which became known as Zuse KG. With contracts initially from Switzerland and then Germany the firm prospered and for many years was second only to IBM in Germany. The Z series continued with relay computers and then fully electro­nic machines. The last of the relay machines was the ZII which became a byword for reliability⁸. As competition grew, and technology changed, so life got tougher and outside funding was required. This eventually led to the company's being absorbed by Siemens.

Zuse is still a consultant; but even more he is a painter, whose work had been described as "a synthesis of ex­pressionism and surrealism, in brilliant colours". One engineering task that he did take up in the 1980s, however, was to rebuild the ZI from memory – as a museum piece.

Task I

Comment on Zuse’s words ” Necessity was no the mother of inventions, it was laziness and boredom: the desire to rid himself of those tedious calculations.”

Task II

Speak on history and characteristics of Z1.

Task III

Describe other Zuse’s computers.