Talk:Z4 (computer)

electronic or relay
Was the Z4 electronic, or did it use relays?--Bubba73 23:07, 7 Jun 2005 (UTC)

first computer
http://www.dai.ed.ac.uk/homes/cam/fcomp.shtml

The above link discusses what should be counted as a computer and mentions the the mechanically based operation of the memory in the Z4, and it not using a stored program so perhaps it should not thought of as the first computer- the link discusses this in some detail.
 * That link discusses a first stored-program computer, not a first computer (there's a difference).

--89.25.210.104 (talk) 19:05, 7 May 2018 (UTC)

Needs clarification
The "251" claimed Zuse computers: is the implication that these are all Z4s? Needs clarification in models. 171.66.161.158 (talk) 22:27, 4 April 2012 (UTC)
 * No of course not. They made lots of later computers. That sentence does seem inappropriate in this article though. Dmcq (talk) 22:40, 4 April 2012 (UTC)

"World's first commercial digital computer"
Both the Z4 article and the BINAC article claim to be the "world's first commerical digital computer:

http://en.wikipedia.org/w/index.php?title=Z4_%28computer%29&oldid=619761555

http://en.wikipedia.org/w/index.php?title=BINAC&oldid=631071670 — Preceding unsigned comment added by 89.14.104.215 (talk) 09:24, 2 November 2014 (UTC)


 * But does one-of-a-kind computer is "commercial"?--89.25.210.104 (talk) 19:05, 7 May 2018 (UTC)

The Z1, Z2, and Z3 articles make the same claim. — Preceding unsigned comment added by 146.131.120.2 (talk) 15:24, 13 December 2016 (UTC)

External links modified
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External links modified
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Only digital computer?
The article makes the claim that "In 1950/1951, the Z4 was the only working digital computer in continental Europe". BARK (computer) became operational on April 28, 1950, but it wasn't a commercial available computer. It probably needs clarification. // Liftarn (talk) 14:14, 16 August 2018 (UTC)

Date of sale - or was it sold at all?
The article states that the Z4 was the second digital computer to be sold, but this is not backed up by any supplied reference as far as I can tell. The article's reference:

states (translation from German by Google):

[in 1949 Professor Stiefel from ETH Zürich] was not a little surprised when he found the Z4, which was already a bit battered from the outside, set up in a horse stable. Nevertheless, he dictated to Zuse a simple differential equation that Zuse could immediately program, demonstrate on the machine and solve. After that he concluded a contract with Zuse: the Z4 should be loaned to the ETH after a thorough overhaul and cleaning.

In 1950 the Z4 was loaded and taken to Zurich. It was her sixth transport. To this day, all those involved remain silent about the exact circumstances of the transport of the Z4 from the Allgäu to Switzerland. On the basis of the political and legal situation at the time, this is also understandable (Control Council laws).

So, the circumstances of the Z4's move from Germany to Switzerland are not publicly known, and this particular source claims that the deal involved a loan not a sale.

On that basis, unless more information can be sourced, it seems that the article should reflect doubt about the Z4 having been sold at all. For example, the article states that the Z4 was constructed for a order placed by Henschel & Son, but not that it had been paid for. Perhaps it had been and therefore Henschel & Son owned the machine as completed in 1945, perhaps it was owned by whatever concern had funded the construction and therefore remained unsold when completed. No references supplied support either position and the article text takes the 1949 deal as the year of the supposed sale; that deal is called a loan in the reference above.

If money did change hands in the 1949 deal (for whatever reason), who owned the Z4 in that year, where did the money come from, and where did it go? The reference above doesn't make that clear and seems to suggest the whole business was at least a bit shady; the reference says Stiefel did a deal with Zuse to acquire the Z4 on loan which on the face of it appears possibly unlawful since it seems unlikely Zuse was the owner of the machine. The reference also suggests that the 'Control Council Laws' might also have been broken by the deal.

If the transfer to ETH was unlawful—it looks like it could have been—it seems to me that the Z4 was rather more stolen than sold or loaned.

It's certainly not clear and I'm equally certainly no lawyer: are there any references to settle this one way or another?

Michael F 1967 (talk) 21:22, 3 May 2023 (UTC)


 * Hi, I hope these passages from Herbert Bruderer's Milestones in Analog and Digital Computing (2021) might clear it up.
 * p. 14 - The Z4 (1945), which has survived to the present time, was the world’s first commercial computer.
 * p. 1070 - The two partners [Zuse and ETH] concluded two very complex agreements. In the main contract of September 7, 1949, the Institute for Applied Mathematics agreed to bear the costs for the reconditioning and the further development of the Z4. In return, the ETH was allowed to use the large machine in Zurich from 1950 to 1955, as defined in the supplementary agreement of September 22/October 8, 1949 (leasing contract). The machine was also pledged to the ETH.
 * p. 1073 – a letter dated October 20, 1949.
 * To the responsible border authorities for the Swiss-German border
 * Dear sirs:
 * In view of the current political uncertainty, we wish to take the precaution of advising you that it is in our interest that you – in the event that conditions arise in Germany in the coming years or circumstances were to lead to grave danger to life and limb for Herr K. Zuse, graduate engineer in Neukirchen, as well as his family and two closest colleagues, graduate engineers Harro Stucken and Alfred Eckard together with their families, compelling them to flee from Germany – do not refuse the above mentioned persons entry to Switzerland if they should turn up at the border to Switzerland under these circumstances. In this case we ask that you contact us immediately by telephone (telephone number Zurich (051) 32 73 30) in order that we have the opportunity to express our standpoint in regard to the issue of their passing the border.
 * Respectfully yours,
 * The President of the Swiss School Board [written by Hans Pallmann]
 * p. 1077 - Regarding the costs of the Zuse relay computer, widely different figures were published. It follows from the agreements between Zuse and the Institute for Applied Mathematics of the ETH Zurich that the ETH financed the reconditioning and expansion of the Z4 (see Figs. 23.6, 23.7, 23.8, and 23.9) (utilizing external funding) with 50,000 Swiss francs. In return, the ETH leased the machine for 5 years for a price of 30,000 francs. Zuse’s final bill of July 26, 1950, for the reconditioning of the Z4 computer was actually in the amount of 56,900 German marks, but the rest was never paid: the amount remained 50,000 francs.
 * p. 1079 - The money for the Z4 did not come from the ETH Zurich, but from the Jubiläumsfonds ETH 1930 (20,000 Swiss francs, commitment of the Board of Trustees of December 27, 1949) and the Huber-Kudlich-Stiftung (30,000 Swiss francs, presidential decree of December 30, 1950). The ETH made an advance payment, since the foundation was not yet established in 1949. Accordingly, for the acquisition of the Z4, the sourcing of financing was the responsibility of the President of the School Board and not of the School Board in its entirety.
 * p. 1083 - The leased electromechanical relay machine [Z4] was installed in July 1950 and was in continuous use from August of the same year.
 * p. 1110 – 1949: Leasing agreement for the Zuse Z4 between the Konrad Zuse-Ingenieurbüro, Neukirchen, Germany, and the Institute for Applied Mathematics.
 * pp. 1139, 1140 - For the reconditioning and use of the Z4 relay machine, total costs of 50,000 Swiss francs (of which 30,000 Swiss francs were for the leasing costs) were agreed. However, a contract extension was agreed later (see Sect. 24.4), but this was not additionally billed. This was presumably cause for a misunderstanding. Although the final bill (see Sect. 24.7) was higher than 50,000 Swiss francs, no supplementary payment was made. The testing of the Z4 (see Sect. 24.5) was performed in the German Neukirchen. The handover (see Sect. 24.6) and the return (see Sect. 24.8) took place in Zurich. Eem dik doun in toene (talk) 20:45, 4 May 2023 (UTC)