Bell labs relay computers
Paul E. Ceruzzi · Encyclopedia of Computer Science · 2003
Between 1939 and 1951, Bell Telephone Laboratories (Bell Labs) built a total of seven digital computing machines of ever-greater sophistication. Each used electromechanical relays and switching equipment for its basic computing elements. The last computers of this series were as functionally powerful as the electronic computers being built elsewhere at that time, but their use of relay switching meant that they would always remain an order of magnitude slower in arithmetic speeds. The inspiration for the initial machines came from George Stibitz, a mathematician at Bell Labs, with the engineering design due at first to Sam Williams and later to E. G. Andrews.