The Z1: Architecture and Algorithms of Konrad Zuse's First Computer (2014) [pdf]

I didn't read the whole document, but I'm amazed how modern the Z1 was.

All-binary architecture, programmable, 24 bit floating point, microcoded ALUs.

The author seems to come to the same conclusion: What I find most surprising is how the young Konrad Zuse could come to such an elegant design for a computing engine. Whereas the ENIAC, or Mark I teams in the US consisted of seasoned scientists and electronic experts, Zuse was working in isolation and without real previous experience. From the architectural point of view, we compute today as Zuse did in 1938, not as the ENIAC did in 1945.

You can see the Z1 replica, as well as an implementation of the Z3 with relays in the Deutsches Technikmuseum - The Museum of Technology, in Berlin.

I was fortunate enough while there to run into Zuse's son, Horst Zuse, also a computer scientist, fixing the Z3!

The pdf mentions... "I could only see a short video of parts of the machine operating (filmed almost 20 years ago)" ... but i cant find a video where the Z1 is actually running. Would be very amazing to see this thing computing :)

A note -- if you're linking to arXiv, it's better to link to the abstract (http://arxiv.org/abs/1406.1886) rather than directly to the PDF. From the abstract, one can easily click through to the PDF; not so the reverse. And the abstract allows one to do things like see different versions of the paper, search for other things by the same authors, etc. Thank you!