Z3 (computer)

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Zuse Z3 replica on display at Deutsches Museum in Munich Z3 Deutsches Museum.JPG
Zuse Z3 replica on display at Deutsches Museum in Munich

The Z3 was a German electromechanical computer designed by Konrad Zuse. It was the world's first working programmable, fully automatic digital computer. [1] The Z3 was built with 2,600 relays, implementing a 22-bit word length that operated at a clock frequency of about 4–5  Hz. Program code was stored on punched film. Initial values were entered manually. [2] [3] [4]

Germany Federal parliamentary republic in central-western Europe

Germany, officially the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, and the Alps to the south. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, France to the southwest, and Luxembourg, Belgium and the Netherlands to the west.

Konrad Zuse German computer scientist and engineer

Konrad Zuse was a German civil engineer, inventor and computer pioneer. His greatest achievement was the world's first programmable computer; the functional program-controlled Turing-complete Z3 became operational in May 1941. Thanks to this machine and its predecessors, Zuse has often been regarded as the inventor of the modern computer.

Computer programming process that leads from an original formulation of a computing problem to executable computer programs

Computer programming is the process of designing and building an executable computer program for accomplishing a specific computing task. Programming involves tasks such as: analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms in a chosen programming language. The source code of a program is written in one or more languages. The purpose of programming is to find a sequence of instructions that will automate the performance of a task on a computer, often for solving a given problem. The process of programming thus often requires expertise in several different subjects, including knowledge of the application domain, specialized algorithms, and formal logic.


The Z3 was completed in Berlin in 1941 but it wasn't considered vital, so it was never put into everyday [5] [2] [3] operation. [6] [7] [8] Based on the work of Hans Georg Küssner (cf. Küssner effect) e.g. a "Program to Compute a Complex Matrix" was written and used to solve wing flutter problems [9] . Zuse asked the German government for funding to replace the relays with fully electronic switches, but funding was denied during World War II since such development was deemed "not war-important". [10] :148 The original Z3 was destroyed on 21 December 1943 during an Allied bombardment of Berlin. The Z3 was originally called V3 (Versuchsmodell 3 or Experimental Model 3) but was renamed to not be confused with Germany's V-weapons. [11] A fully functioning replica was built in 1961 by Zuse's company, Zuse KG, and is on permanent display at Deutsches Museum in Munich. [12]

Berlin Capital of Germany

Berlin is the capital and largest city of Germany by both area and population. Its 3,748,148 (2018) inhabitants make it the second most populous city proper of the European Union after London. The city is one of Germany's 16 federal states. It is surrounded by the state of Brandenburg, and contiguous with its capital, Potsdam. The two cities are at the center of the Berlin-Brandenburg capital region, which is, with about six million inhabitants and an area of more than 30,000 km², Germany's third-largest metropolitan region after the Rhine-Ruhr and Rhine-Main regions.

Küssner effect

In fluid dynamics, the Küssner effect describes the unsteady aerodynamic forces on an airfoil or hydrofoil caused by encountering a transverse gust. This is directly related to the Küssner function, used in describing the effect. Both the effect and function are named after Hans Georg Küssner (1900–1984), a German aerodynamics engineer.

World War II 1939–1945 global war

World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.

The Z3 was demonstrated in 1998 to be, in principle, Turing-complete. [13] However, because it lacked conditional branching, the Z3 only meets this definition by speculatively computing all possible outcomes of a calculation.

Thanks to this machine and its predecessors, Konrad Zuse is often regarded as the inventor of the computer. [14] [15] [16] [17]

Design and development

Zuse designed the Z1 in 1935 to 1936 and built it from 1936 to 1938. The Z1 was wholly mechanical and only worked for a few minutes at a time at most. Helmut Schreyer advised Zuse to use a different technology. As a doctoral student at the Berlin Institute of Technology in 1937 he worked on the implementation of Boolean operations and (in today's terminology) flip-flops on the basis of vacuum tubes. In 1938 Schreyer demonstrated a circuit on this basis to a small audience, and explained his vision of an electronic computing machine – but since the largest operational electronic devices contained far fewer tubes this was considered practically infeasible. [18] In that year when presenting the plan for a computer with 2,000 electron tubes, Zuse and Schreyer, who was an assistant at Prof. Wilhelm Stäblein's Telecommunication Institute at the Technical University of Berlin, were discouraged by members of the institute who knew about the problems with electron tube technology. [19] Zuse later recalled: “They smiled at us in 1939, when we wanted to build electronic machines … We said: The electronic machine is great, but first the components have to be developed.” [20] In 1940 Zuse and Schreyer managed to arrange a meeting at the Oberkommando der Wehrmacht (OKW) to discuss a potential project for developing an electronic computer, but when they estimated a duration of two or three years, the proposal was rejected. [21]

Z1 (computer)

The Z1 was a mechanical computer designed by Konrad Zuse from 1936 to 1937 and built by him from 1936 to 1938. It was a binary electrically driven mechanical calculator with limited programmability, reading instructions from punched celluloid film.

Helmut Theodor Schreyer was a German inventor. He is mostly known for his work on the Z3, one of the first computers.

Flip-flop (electronics) circuit that has two stable states and can be used to store state information

In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems.

Zuse decided to implement the next design based on relays. The realization of the Z2 was helped financially by Dr. Kurt Pannke, who manufactured small calculating machines. The Z2 was completed and presented to an audience of the Deutsche Versuchsanstalt für Luftfahrt ("German Laboratory for Aviation") in 1940 in Berlin-Adlershof. Zuse was lucky – this presentation was one of the few instances where the Z2 actually worked and could convince the DVL to partly finance the next design. [18]

The Z2 was a mechanical and relay computer completed by Konrad Zuse in 1940. It was an improvement on the Z1, using the same mechanical memory but replacing the arithmetic and control logic with electrical relay circuits. Photographs and plans for the Z2 were destroyed by the Allied bombing during World War II. In contrast to the Z1, the Z2 used 16-bit fixed-point arithmetic instead of 22-bit floating point.

Improving on the basic Z2 machine, he built the Z3 in 1941, which was a highly secret project of the German government. [22] Dr. Joseph Jennissen (1905–1977), [23] member of the "Research-Leadership" (Forschungsführung) in the Reich Air Ministry [24] acted as a government supervisor for orders of the ministry to Zuse's company ZUSE Apparatebau. [25] A further intermediary between Zuse and the Reich Air Ministry was the aerodynamicist Herbert A. Wagner. [26]

The Z3 was completed in 1941 and was faster and far more reliable than the Z1 and Z2. The Z3 floating-point arithmetic was improved over that of the Z1 in that it implemented exception handling "using just a few relays", the exceptional values (plus infinity, minus infinity and undefined) could be generated and passed through operations. The Z3 stored its program on an external tape, thus no rewiring was necessary to change programs. [27]

On 12 May 1941 the Z3 was presented to an audience of scientists including the professors Alfred Teichmann and Curt Schmieden [28] of the Deutsche Versuchsanstalt für Luftfahrt ("German Laboratory for Aviation") in Berlin, [29] today known as the German Aerospace Center in Cologne.

Zuse moved on to the Z4 design, which was built just days before World War II ended.

The Z3 as a universal Turing machine

It was possible to construct loops on the Z3, but there was no conditional branch instruction. Nevertheless, the Z3 was Turing-complete – how to implement a universal Turing machine on the Z3 was shown in 1998 by Raúl Rojas. [13] [30] He proposes that the tape program would have to be long enough to execute every possible path through both sides of every branch. It would compute all possible answers, but the unneeded results would be canceled out (a kind of speculative execution). Rojas concludes, "We can therefore say that, from an abstract theoretical perspective, the computing model of the Z3 is equivalent to the computing model of today's computers. From a practical perspective, and in the way the Z3 was really programmed, it was not equivalent to modern computers."

From a pragmatic point of view, however, the Z3 provided a quite practical instruction set for the typical engineering applications of the 1940s – Zuse was a civil engineer who only started to build his computers to facilitate his work in his main profession.

Relation to other work

The success of Zuse's Z3 is often attributed to its use of the simple binary system. [31] This was invented roughly three centuries earlier by Gottfried Leibniz; Boole later used it to develop his Boolean algebra. Zuse was inspired by Hilbert's and Ackermann's book on elementary mathematical logic (cf. Principles of Mathematical Logic). [19] In 1937, Claude Shannon introduced the idea of mapping Boolean algebra onto electronic relays in a seminal work on digital circuit design. Zuse however did not know Shannon's work and developed the groundwork independently [10] :149 for his first computer Z1 which he designed and built from 1935 to 1938.

Zuse's coworker Helmut Schreyer built an electronic digital experimental model of a computer using 100 vacuum tubes [32] in 1942, but it was lost at the end of the war.

An analog computer was built by the rocket scientist Helmut Hölzer in 1942 at the Peenemünde Army Research Center to calculate and simulate [33] [34] [35] V-2 rocket trajectories [36] [37] .

The Tommy Flowers-built Colossus (1943) [38] and the Atanasoff–Berry Computer (1942) used thermionic valves (vacuum tubes) and binary representation of numbers. Programming was by means of re-plugging patch panels and setting switches.

The ENIAC computer, completed after the war, used vacuum tubes to implement switches and used decimal representation for numbers. Until 1948 programming was, as with Colossus, by patch leads and switches.

The Manchester Baby of 1948 and the EDSAC of 1949 were the world's first computers that stored program instructions and data in the same space. In this they implemented the stored-program concept which is frequently (but erroneously) attributed to a 1945 paper by John von Neumann and colleagues. [39] [40] Von Neumann is said to have given due credit to Alan Turing, [41] and the concept had actually been mentioned earlier by Konrad Zuse himself, in a 1936 patent application (that was rejected). [42] [43] Konrad Zuse himself remembered in his memoirs: "During the war it would have barely been possible to build efficient stored program devices anyway." [44] and Friedrich L. Bauer wrote: "His visionary ideas (live programs) which were only to be published years afterwards aimed at the right practical direction but were never implemented by him." [45]


Modern reconstructions

Z3 reconstruction in 2010 by Horst Zuse Finder Relais Zuse Z3.jpg
Z3 reconstruction in 2010 by Horst Zuse

A modern reconstruction directed by Raúl Rojas and Horst Zuse started in 1997 and finished in 2003. It is now in the Konrad Zuse Museum in Hünfeld, Germany. [47] [48] Memory was halved to 32 words. Power consumption is about 400 W, and weight is about 30 kilograms (66 lb). [49]

In 2008 Horst Zuse started reconstruction of Z3 by himself. [50] It was presented in 2010 in the Konrad Zuse Museum in Hünfeld. [51] [52]

See also

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Z4 (computer)

The Z4 was the world's first commercial digital computer, designed by German engineer Konrad Zuse and built by his company Zuse Apparatebau in 1945. The Z4 was Zuse's final target for the Z3 design, but like Z2 it was partly mechanical (memory) and electromechanical machine.

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The Z22 was the seventh computer model Konrad Zuse developed. One of the early commercial computers, the Z22's design was finished about 1955. The major version jump from Z11 to Z22 was due to the use of vacuum tubes, as opposed to the electromechanical systems used in earlier models. The first machines built were shipped to Berlin and Aachen.

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Horst Zuse German software engineer

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The Zuse Z25 was a program-controlled electronic computer using transistors developed by Zuse KG in Bad Hersfeld and put into production in 1963. The word length was 18 bits, though it could also process double-word lengths for accuracy up to 10 decimal digits. The addressable space was 32768 words. The maximum size of the magnetic core memory was 16383 words. The programmable program memory had a maximum size of 4096 words.

The Zuse Z23 was a transistorized computer first delivered in 1961, designed by the Zuse KG company. A total of 98 units were sold to commercial and academic customers up till 1967. It had a 40 bit word length and used an 8192 word drum memory as main storage, with 256 words of rapid-access ferrite memory. It operated on fixed and floating point binary numbers. Fixed-point addition took 0.3 milliseconds, a fixed point multiplication took 10.3 milliseconds. It was similar in internal design to the earlier vacuum tube Z22. Related variants were the Z25 and Z26 models.


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Further reading