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Konrad Zuse's Guestbook: a Treasure Trove

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The guestbook of Konrad Zuse, which is preserved in the Deutsches Museum in Munich, is now available online: NL 207 Zuse, Konrad - Gästebuch von Konrad Zuse - Deutsches Museum Digital ( It provides new insights into the early days of computer science in Europe.

The following overview contains selected entries from the post-war period until 1960.



Entries in the guestbook




27 April 1946

Alwin Walther

TH Darmstadt

20 May 1947

Louis Couffignal

CNRS, Paris

18 February 1949

Max Lattmann

Contraves, Zurich

13 July 1949

Eduard Stiefel

ETH Zurich

13 July 1949

Hans Brändli

Contraves, Zurich

18 January 1950

Eduard Stiefel

ETH Zurich

18 January 1950

Heinz Rutishauser

ETH Zurich

18 January 1950

Ambros Speiser

ETH Zurich

21 April 1950

Ambros Speiser

ETH Zurich

21 April 1950

Friedrich Willers

TH Dresden

22 March 1953

Heinz Rutishauser

ETH Zurich

31 March 1953

Heinrich Wild

Kern, Aarau

12 March 1957

Hugo Kasper

Wild Heerbrugg

19 September 1957

Ambros Speiser

IBM Research, Zurich

2 March 1959

Heinz Zemanek

TH Wien, Vienna


TH means Technological University.

In 1947, Zuse lived in Hopferau (Bavaria), followed by relocation to Neukirchen (Hünfeld district) in 1949 and Bad Hersfeld in 1957.

Early visit of the French pioneer Couffignal

There were comparatively few entries from abroad, where Zuse was obviously hardly known. The early meeting with Couffignal, an unsuccessful French computer pioneer, is striking:

"In 1946, Couffignal spent time with Aiken in Cambridge (Massachusetts) and von Neumann in Princeton and also in Philadelphia. In 1951, he organized an international conference at the Centre national de la recherche scientifique (CNRS) in Paris. Even with his second plan, Couffignal had no luck: the vacuum tube computer developed from 1947 to 1952 at the Laboratoire de calcul mécanique of the Institut Blaise Pascal in Chatillon (southwest of Paris) never operated." (see Herbert Bruderer: Milestones in Analog and Digital Computing, Springer Nature Switzerland AG, Cham, 3rd edition 2020, volume, 2, page 1199,

Meeting with Dutch pioneer van Wijngaarden

In the spring of 1950, Adriaan van Wijngaarden also visited Zuse. However, an exact date is missing.

"The Arra (automatische relais rekenmachine Amsterdam) was built in the computation section of the Mathematisch Centrum Amsterdam (project head: Adriaan van Wijngaarden; computer design and construction, Bram Jan Loopstra and Carel S. Scholten). The Mathematisch Centrum is now called the Centrum Wiskunde & Informatica (CWI). The Arra 1 relay machine was completed in 1952 but was a failure and was practically useless. However, the Arra 2, built by Gerrit Anne Blaauw in 1954, was successful." (see Herbert Bruderer: Milestones in Analog and Digital Computing, Springer Nature Switzerland AG, Cham, 3rd edition 2020, volume, 2, page 1204).

Experts from Switzerland rent the Zuse Z4

The question of how and when ETH Zurich learned about Zuse's relay computer V4 (later Z4) is still unclear. Thanks to the guest book, which is now accessible online, we know that the technical director of Contraves AG, Zurich, Max Lattmann, met Zuse on February 18, 1949. Lattmann had been a member of the commission for the development of computing machines in Switzerland since 1948. Its chairman was Prof. Eduard Stiefel, head of the Institute for Applied Mathematics, ETH Zurich. Contraves, founded in 1936, was a weapons manufacturer. Among other things, it built analog computers (differential analyzers). The meeting of Stiefel and Hans Brändli (director of Contraves) on July 13, 1949 was decisive for Zuse. It resulted in ETH Zurich financing the extension of the Z4 and renting the machine from 1950 to 1955. This meant scientific recognition for the completely impoverished German computer inventor.

"January 15–20, 1950, in Neukirchen, Germany (Zuse KG): Meeting to discuss the supplementary agreement for the Z4. Eduard Stiefel, Heinz Rutishauser, and Ambros Speiser traveled to Germany." (see Herbert Bruderer: Milestones in Analog and Digital Computing, Springer Nature Switzerland AG, Cham, 3rd edition 2020, volume, 2, page 1137).

Cooperation with Photogrammetry

I owe the following information about visitors from Aarau and Heerbrugg to Aldo Lardelli of the Kern Collection in the Stadtmuseum Aarau (Kern & Co. AG ÷ 1819 to 1991 in Aarau, factory for precision mechanics, optics and electronics) (Willkommen - Kern Aarau (

At the end of March 1953, two specialists from Aarau met Zuse, including Heinrich Wild. He was director of Kern & Co. AG. He was "fully committed to the acquisition of the first electronic computer in 1954." (see Bulletin No. 11, 1968, Kern & Co. AG., page 9).

In mid-March 1957, two experts from Heerbrugg followed, including Hugo Kasper, head of the photogrammetric department of Wild Heerbrugg, later professor of geodesy, in particular photogrammetry, at ETH Zurich (see Alessandro Carosio: Das Institut für Geodäsie und Photo-grammetrie der ETH Zurich von 1855 bis 2008, Eidgenössische Technische Hochschule Zürich, Institut für Geodäsie und Photogrammetrie, Report 308, December 2009, page 7). Relationship between the two companies:

"The Graphomat Z64 (1961) was a perforated tape/punched card controlled flatbed plotter (in transistor technology). The device was originally equipped with relays and was developed in collaboration with the Wild Heerbrugg AG (now Leica Geosystems AG)." (see Herbert Bruderer: Milestones in Analog and Digital Computing, Springer Nature Switzerland AG, Cham, 3rd edition 2020, volume, 2, page 1027).

Willers and Zemanek

In 1947 and 1948, visits from the U.S. are recorded, in 1950 from the U.K. and the U.S. (Remington Rand, a client of Zuse KG). In the next few years, other pioneers arrived: Friedrich Willers (1950) from the GDR and Heinz Zemanek (1959) from Austria. A universal transistor computer (D4a) was later developed at the Institute for Automatic Computing at the Technical University of Dresden (Willers). Zemanek from the Vienna University of Technology built the Mailüfterl in 1958, one of the first transistor computers in Europe.

However, the guest book is incomplete

From September 27 to October 12, 1949, Corrado Böhm and Harry Laett (ETH Zurich) prepared a test report on the Z4 in Neukirchen. In June/July 1950 Heinz Rutishauser traveled to the Zuse KG. Nothing was found on this.



Herbert Bruderer is a retired lecturer in didactics of computer science at ETH Zurich. More recently, he has been an historian of technology., herbert.bruderer@bluewin.


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