Electromechanical programmable computer

The electromechanical programmable computer emerged in 1930s Berlin in near-complete isolation from the rest of the computing world. While American and British researchers would later develop similar machines with military funding and institutional support, Konrad Zuse built his computers in his parents' living room, funded by family money and small grants, knowing nothing of developments elsewhere.

Zuse was a civil engineering student who grew frustrated with the tedious calculations required for structural analysis. In 1936, he began designing a machine that could automate these computations. His approach was remarkably sophisticated: binary arithmetic, floating-point numbers, and a separation between memory and processor that anticipated modern computer architecture. On April 11, 1936, he applied for a patent on his electromagnetic, program-controlled calculator.

The Z1, completed in 1938, used 30,000 metal parts to implement a mechanical binary calculator that read instructions from punched celluloid film. It was the first freely programmable computer using Boolean logic and binary floating-point arithmetic. But the mechanical components were unreliable—Zuse had machined them himself with limited precision—and the machine never worked consistently.

The adjacent possible for Zuse's work included the punched-card tabulating machines that had existed since Hollerith's 1890 census machine, the theoretical work on mechanical computation dating to Babbage's designs, and the telephone relay switches that would prove more reliable than his mechanical parts. But Zuse didn't know about much of this prior work. He reinvented concepts independently, including a programming language he called Plankalkül—the first high-level programming language, though it wasn't implemented until decades later.

The Z3, completed on May 12, 1941, achieved what the Z1 could not. Using 2,600 telephone relays instead of mechanical parts, it became the world's first working programmable, fully automatic digital computer. Operating at 5-10 Hz with a 22-bit word length, it performed floating-point arithmetic and read programs from punched film. The German aviation industry used it for aerodynamic calculations.

Both the Z1 and Z3 were destroyed in the bombing of Berlin in December 1943, along with all construction plans. Zuse's isolation meant his pioneering work had no influence on the American and British computer programs that would shape the industry. The convergent evolution is striking: Zuse, Alan Turing, and the ENIAC team all arrived at similar concepts independently, proving that the conditions for digital computation had aligned globally.

Zuse later built the Z4, which survived the war and became the world's first commercial computer. The Deutsches Technikmuseum in Berlin now displays replicas of his machines, monuments to innovation that flourished in isolation and was lost to history's broader currents.