1935-1936 (z1):
The first program controlled computer, Z1, was invented by Konrad Zuse. The computer used the binary system and todays standard of storage and control. The computer had many aspects that modern computers have such as, a control unit, memory, micro sequences, floating point logic (Only the logical unit was not realised at the time) and input output devices. The machine was capable of adding and subtracting. It had some control logic which made it able to perform more complicated things like multiplication and subtraction. It performed multiplication by adding multiple times and division by subtracting multiple times. This computer is the first of a series. The computer was destroyed in WWII in the bombardment of Berlin in December 1943. 

1939 (Z2):
The Z2 was designed by Konrad Zuse. This was an improvement on the Z1. It used the same mechanical memory that the Z1 used, but it replaced the arithmetic and control logic with electromechanical relays circuits. The Z2 was completed in 1939 with the help of Dr. Kurt Pannke who partially funded it. It was presented to the Deutsche Versuchsanstalt für Luftfahrt (German Laboratory for Aviation). During the presentation, the computer worked and managed to convince the Deutsche Versuchsanstalt für Luftfahrt into funding part of the next design (Z3). The plans for it, the machine, and any photographs of it were destroyed by the Allied bombing in WWII.

1941 (z3):
The Z3 was invented by Konrad Zuse. It was the third in the Z1 series. This was the world’s first working programmable, fully automatic computer. By todays standards the Z3 was the world’s first computer. It was completed in 1941 in Berlin and it was a vast improvement on the Z1 and Z2. The computer stored it’s programs on an external tape, so that rewiring wasn't NECESSARY to  change the program. The computer was a highly secret project for the German government. Dr. Jenissen, member of the Reich Air Ministry acted as a government supervisor for orders of the ministry to Zuse's company ZUSE Apparatebau. The German Aircraft Research Institute used the computer to perform statistical analyses of wing flutter. On 12 May 1941, the computer was presented in Berlin to scientists which included the professors Alfred Teichmann and Curt Schmieden of the Deutsche Versuchsanstalt für Luftfahrt (German Laboratory for Aviation). The original Z3 was destroyed in 1943 in a bombing of Berlin. A replica was built in the 1960s by Zuse's company, Zuse KG, and is on permanent display in the Deutsches Museum.

1945 (z4):
The Z4 was designed by Konrad Zuse. It was one of the world’s first commercial computers. It was built between 1942 and 1945. This computer is the last target for the Z1 series. The design was similar to the Z3, but the computer was significantly enhanced in several ways. Zuse worked on the Z4 in 1944 with around two dozen people. To prevent the computer from falling into the hands of the Soviets, the Z4 was evacuated from Berlin in February 1945 and transported to Göttingen. It was completed there at the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute). But when it was presented to scientists of the AVA the approaching front could be heard, so the Z4 was transported in a truck to Hinterstein in Bad Hindelang, where Konrad Zuse is said to have met Wernher von Braun. The computer was delivered to Swiss Federal Institute of Technology Zurich (ETH Zurich) in September 1950 to work on equations and other projects when Eduard Stiefel purchased it. In 1950/1951 the Z4 was the only working computer in Europe, and the second one to be sold in the world. In 1954, the computer was transferred to the Institut Franco-Allemand des Recherches de St. Louis (Franco-German Institute of Research) in France, where it was used until 1959. Today, the Z4 is on display in the Deutsches Museum in Munich.

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