Hi Paul:

This correspondence causes me to recall that in the early 1970s, when I was arranging to have several of Zuse’s and Schreyer’s papers translated into English,

for inclusion in my book “The Origins of Digital Computers” (Springer Verlag, 1973), I was very intrigued by Zuse’s “Mechanical Switching Element”, as portrayed in Figure 2 of his 1962 paper “Entwicklungslinien einer Rechengeräte-Entwicklung von der Mechanik zur Elektronic” (“The Outline of a Computer Development from Mechanics to Electronics”). So, I constructed a model Mechanical Switching Element out of little glued-together sheets of clear perspex (the largest of which were about 3.3cm x 1.3cm x 0.1cm), plus a 0.6cm-long floating metal rod (part of a gramophone needle). This model closely matched the scale of the diagram Zuse had provided in his paper – I didn’t and don’t know the dimensions of his actual switching elements. Despite my limited mechanical skills, the model switching element worked very well, and being transparent its operation was easily demonstrated. I used to keep it in my shirt pocket and show it off whenever the opportunity presented itself. Unfortunately, I lost the little model many years ago. Each time I look at Figure 2 I regret this loss! 😊

Cheers

Brian

From: Members <members-bounces@lists.sigcis.org> on behalf of "Ceruzzi, Paul via Members" <members@lists.sigcis.org>
Reply to: Paul Ceruzzi <CeruzziP@si.edu>
Date: Saturday, 8 July 2023 at 17:44
To: Evan Koblentz <evank@njit.edu>, Jesper Juul <j@jesperjuul.net>
Cc: "members@lists.sigcis.org" <members@lists.sigcis.org>
Subject: Re: [SIGCIS-Members] Zuse / binary

Fascinating discussion. Zuse told me that he was taught binary arithmetic in grade school, but he only learned of Leibniz's essay on binary (ca. 1680) after Zuse began work on computers. Babbage was an admirer of Leibniz's work but did not consider binary for his engines.  The Z1, which had a binary calculating unit, did not work well, and therefore Zuse adopted electromagnetic relays (a technology not available to Babbage) for his later machines, which did work. Attempts to reconstruct the Z1 for the Deutsches Technikmuseum using late 20th-Century machine tools also failed --  please correct me if I am mistaken. But note that Zuse built a successful mecahnical binary memory unit for the Z4, which not only worked well but which was in steady service at the ETH in Switzerland for years. The joke was that the clicking of the Z4 relays was the loudest noise in Zurich on any given evening. The Z4 is now at the Deutsches Museum in Munich.

Paul Ceruzzi

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From: Members <members-bounces@lists.sigcis.org> on behalf of Jesper Juul via Members <members@lists.sigcis.org>
Sent: Saturday, July 8, 2023 8:05 AM
To: Evan Koblentz <evank@njit.edu>
Cc: members@lists.sigcis.org <members@lists.sigcis.org>
Subject: Re: [SIGCIS-Members] Zuse / binary

External Email - Exercise Caution

In Raúl Rojas' paper on the Z1/Z3(1), he writes that "instead of using gears (as Babbage had done in the previous century), Zuse implemented logical and arithmetical operations using sliding metallic rods. The rods could move in only one of two directions (forward or backward) and therefore were appropriate for a binary machine." The Z1 is 1936-38. 

This doesn't quite explain if rods or binary arithmetic came first, but there is a footnote to Zuse's book "Der Computer mein Lebenswerk".

As a side note, I can recommend seeing the Z1 in the Technical Museum in Berlin if you are near.

Jesper Juul

1) https://ed-thelen.org/comp-hist/Zuse_Z1_and_Z3.pdf

On Fri, 7 Jul 2023 at 18:34, Evan Koblentz via Members <members@lists.sigcis.org> wrote:

What are some good articles addressing why Zuse, Aiken, Stibitz, etc.
decided to use binary (or not)?

--
Evan Koblentz

New Jersey Institute of Technology
- Senior Writer, Office of Communications and Marketing
- Adjunct Instructor, Ying Wu College of Computing
- Faculty/Staff Advisor, NJIT Lego Club

evank@njit.edu
(973) 596-3065
https://web.njit.edu/~evank

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