Z4 (computer)

Z4 (computer). The **Z4** was an electromechanical computer designed by the pioneering German engineer Konrad Zuse. Completed in 1945, it was the world's first commercial digital computer and one of the earliest working programmable machines. After surviving World War II, it was installed at the ETH Zurich in 1950, where it served for several years as a vital scientific calculation tool.

History

The development of the **Z4** began under the auspices of the German Aircraft Research Institute during the latter stages of World War II. To protect it from Allied bombing raids, Konrad Zuse moved the partially completed machine from Berlin to the village of Hinterstein in the Allgäu Alps. After the war, the computer was discovered by the mathematician Eduard Stiefel of ETH Zurich. In 1949, Zuse KG finalized its construction, and it was leased to the Institute for Applied Mathematics at ETH Zurich, becoming operational in 1950. For five years, it was used for critical calculations in fields like aerodynamics and ballistics, supporting projects for entities such as the French aircraft manufacturer SNECMA and the Swiss Federal Institute of Technology.

Design and construction

Like its predecessor, the Z3 (computer), the **Z4** was a relay-based electromechanical computer. Its design featured a sophisticated punched tape reader for program input and a complex memory unit. The machine's construction utilized approximately 2,200 relays for the arithmetic unit and control logic, along with a unique mechanical memory storage device. This memory, an evolution of the design used in the Z1 (computer), consisted of rotating metal plates with slots to represent binary values. The entire apparatus was housed in several large cabinets, reflecting the substantial physical scale of early computing technology.

Technical specifications

The **Z4** operated on a binary numeral system and used floating-point arithmetic for enhanced precision. Its clock speed was a modest 40 Hz. The machine had a word length of 32 bits and featured a two-address instruction set. Its most notable component was the mechanical memory, which could store 64 words. For permanent program and data storage, it employed 35 mm film punched tape, a medium also used in contemporary German cryptography devices like the Lorenz cipher. The arithmetic unit could perform addition in about 0.5 seconds, while multiplication took roughly 3 seconds.

Operation and programming

Operating the **Z4** was a hands-on, physical process. Programs and data were prepared offline by punching holes into lengths of 35 mm film, which were then fed into the machine's reader. An operator monitored the computation through panels of indicator lights and manually initiated steps. The machine's conditional branching capability, a significant advancement over the Z3 (computer), allowed for more complex problem-solving. It was primarily used for solving complex systems of equations and performing calculations for Swiss aerospace engineering projects, including work on the P-16 jet fighter under the guidance of Eduard Stiefel.

Significance and legacy

The **Z4** holds a pivotal place in the history of computing as the first computer to be sold commercially, marking the transition from experimental laboratory devices to practical business machines. Its successful installation at ETH Zurich provided invaluable practical experience to a generation of European computer scientists, including the later founder of Algol, Heinz Rutishauser. The machine's relay-based logic directly influenced the design of early Swiss computers like the ERMETH. Today, the original **Z4** is preserved at the Deutsches Museum in Munich, serving as a key artifact from the dawn of the digital age conceived by Konrad Zuse.

Category:Early computers Category:German inventions Category:History of computing hardware