David Kaiser writes:
John von Neumann, the legendary mathematician, was gripped by a vision as remarkable as Charles Babbage’s a century before: perhaps one could build a machine to calculate. Von Neumann was motivated not only by curiosity about the workings of the brain and the essence of cognition: he needed to know whether various designs for nuclear bombs would go boom or bust. During the war, calculations like these were largely carried out by chains of human operators armed with handheld Marchant calculators. That rough-and-ready process had worked well enough for wartime calculations pertaining to fission bombs. But hydrogen bombs were a whole different beast – not just in potential explosive power, but computationally as well. They required, or so von Neumann concluded, a fully automated means of solving many complicated equations at once. They required an electronic, digital computer that could execute stored programs.