Berlin Technik Museum and the Zuse Z1

The Berlin Technical Museum, officially the Deutsches Technik Museum, has a big collection of trains, planes, and ships, not to mention textiles, luggage manufacturing, jewellery manufacturing, and more. But I'm going to focus on the computing section and the Zuse computers. As the museum publicity says:

The first computers were not built in a garage in Silicon Valley in California, but rather in a living room in Berlin’s Kreuzberg district.

The Zuse Z1

I've said before that depending on your definition, you can make the first computers be from the US (ENIAC), Britain (EDSAC or Colossus), or Germany. The German claim to fame is Conrad Zuse's Z1. This is the focus of the Zuse exhibition in the museum. Despite the paragraph from the museum's advertising, I don't think there is any case to be made for the first computer being built in Silicon Valley. Silicon Valley was just orchards with little tech until Shockley moved there in 1955.

The Zuse Z1 was an electromechanical computer. Above are views from above and from the side. The 1938 original was destroyed during the war, and this is a 1989 reproduction built by Zuse himself.

It is not clear from the exhibition how the computer worked. The museum describes it as:

Konrad Zuse finished his Z1 in 1938. The computer was freely programmable. It worked by controlling mechanical switching elements that pushed metal pins into two different positions: position “0” and position “1.” This binary principle is still the basis of every computer. The Z1 was destroyed during World War II. Konrad Zuse therefore built a model of his pioneering computer for the Deutsches Technikmuseum in 1989. 

The program was stored externally, punched into blank 35mm film stock. Each row of holes represented an instruction. As you can see from the above card, the machine had a clock cycle of a second. It was basically a 22-bit floating-point adder/subtractor. It could do multiplication by repeated addition and shifting and division by repeated subtraction.

Here is a photo of the Z1 element, described by the museum as a "mechanical gate" although I'm pretty sure it is a storage element. The Zuse Z1 did not use electromechanical relays, Zuse used those for later models. The Z2 had relays for calculation but kept this storage element, and then the Z3 was all relays, and the Z4 went back to using the Z1 storage element.

How It Worked

This article, The Other First Computer: Konrad Zuse and the Z3, does a deeper dive into how the computer worked, and the history of Zuse and the early machines. If you really want to go deep, then Reconstruction of mechanical logic gates and memory element of the Zuse Z1 programmable calculator using a 3D-printer does just what it says. It also includes animations of the gates in operation.

Here's a video of how the basic adder worked. It's in German but it's worth watching anyway (21 minutes):

The Z3 and Z4 were later models, and they can be seen in the Deutsches Museum in Munich. See my post German Computer Museums for more details and photos. There doesn't seem to be an example of the relay-based Z2 on display anywhere. Zuse went on to build many subsequent models, one based on tubes, and then on transistors. The exhibit has many of the later models too.

For example, here is the Zuse Z25, which is a 1963 vintage but actually looks more modern than that. It had a clock frequency of 294KHz, and could do 10,000 additions per second (0.01 MIPS?). it had up to 16K bytes of ferrite core memory and a 38-kilobyte drum memory.

But it did not really end well. From a label in the exhibition:

In 1949, the company Zuse KG was founded in Neukirchen (Hessen). At the outset, Konrad Zuse directed the firm with great success, and together with his associates developed mainframe computing installations for science, government, and industry. In the 1960s, however, the firm was unable to keep up with international competition and, in 1967, it was taken over by Siemens. Altogether, Zuse KG sold about 250 mainframe computers.

Learn More

I've not been there, but I suspect if you want to learn more then the place to go is the Konrad-Zuse-Museum in Hünfeld (near Frankfurt). It seems to be open from 3:00pm to 5:00pm every day. The website is entirely in German and I expect the museum is, too.

There is also the Konrad Zuse Internet Archive (in English, although many of the papers are in German).

Other Museums

This is one of my occasional posts about technology museums around the world. For details of the others, see my post Museums: Technology around the World.

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