Technology History | Methfesselstraße, Berlin — 2,600 Relays in a Flat, and a Plaque That Overreaches

On 12 May 1941 Konrad Zuse showed a working machine to an audience of aeronautics researchers in Berlin. It ran on about 2,600 telephone relays and did arithmetic in 22-bit floating point. The Z3 read its program from punched film, clattered rather than glowed, and could not branch conditionally. It was also, on any fair reading, the first working programmable and fully automatic computer in the world. That qualifier is doing necessary work. Electromechanical, not electronic; programmed from tape, not from its own memory; and the frequently repeated claim that it was Turing-complete rests on a theoretical construction Raul Rojas published in 1998, not on anything the machine was designed or used to do. The plaque on Methfesselstraße makes no such distinctions. It states that in 1941 the Zuse Z3 went into operation as the world's first functioning computer, which is the sentence this collection exists to complicate. The work happened in ordinary flats. Zuse built the Z1 through Z4 between 1936 and 1944 in the houses at Methfesselstraße 10 and 7, the earliest of them assembled in his parents' apartment with help from friends and money from a calculator manufacturer. Both houses were destroyed by bombing, and the Z3 with them, in 1943. What Zuse was doing was not separable from the war: the machine was demonstrated to and partly funded through aeronautics research, and his day job at Henschel was aircraft work. The plaque has had a difficult life of its own. It was unveiled on 28 August 1998 with Zuse's son Horst present, after an earlier plan to install it in 1995 lapsed; it disappeared in January 2022, and a replacement went up that November. A rebuilt Z3 stands in the Deutsches Museum in Munich, where you can see the racks of relays that the plaque's single sentence stands in for. Kreuzberg gives you the street and nothing else. The buildings Zuse worked in are gone, the ones there now are postwar, and the whole of the claim is a rectangle of white on a brick wall near the corner. Cover: photo by Axel Mauruszat, Attribution licence, via Wikimedia Commons. It was taken in 2007 and shows the original 1998 plaque, the one that was stolen.