Z3 (computer)
Konrad Zuse demonstrates the Z3 to invited experts in Berlin
View full image ↗ How was this image made?
The creative brief sent to the image model. These are instructions, not a record of what actually happened.
Original prompt & settings (JSON) ↗The landmark demonstration took place at a Berlin address before a handful of invited experts — not, as often claimed, before the public.
12 May 1941: a private audience in Kreuzberg
Konrad Zuse demonstrated the working Z3 on 12 May 1941 at Methfesselstraße 7 in Berlin-Kreuzberg, to a small invited group of experts rather than to the general public.
The audience included Alfred Teichmann and Curt Schmieden of the German Laboratory for Aviation, whose researchers were interested in automated engineering calculations.
Zuse had built the machine through his firm, Zuse-Apparatebau.
About 2,000 relays, clicking at 5 to 10 Hz
The demonstrated machine executed programs from external punched tape and performed binary floating-point arithmetic automatically with electromechanical relays — about 2,000 of them, on a 22-bit word, clocked at roughly 5 to 10 Hz.
Changing programs did not require rewiring: the instructions arrived on punched film outside the machine. It was electromechanical, not electronic.
Loops were possible only by physically joining the tape into a loop; the instruction set contained no conditional branch.
What the priority claims will and will not carry
Authoritative sources call the Z3 the first functioning, freely programmable binary computer, or one of the first working programmable fully automatic machines. Blunter labels such as "the first computer" depend entirely on definitions.
Raúl Rojas showed in 1998 that a looped tape and arithmetic simulation could make the Z3's computing model universal in principle — which is not the same as practical modern-style branching.
The demonstration was not a launch: use remained limited while Zuse moved on to the Z4 and filed a patent application for the Z3 principle on 16 June 1941.
Sources
Researched 23 Aug 2026 5 sources 2 audit passes
How this was checked
Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →
What the sources leave uncertain
- The date and private demonstration are well documented. Priority labels such as “first computer” depend on definitions: authoritative sources more precisely call the Z3 the first functioning, freely programmable binary computer or one of the first working programmable fully automatic machines.
- The Z3 lacked a conditional-branch instruction. Raúl Rojas showed in 1998 that a looped tape and arithmetic simulation could make its computing model universal in principle; that is not the same as practical modern-style branching.