IBM 701

The IBM 701 Electronic Data Processing Machine, known during development as the Defense Calculator, was the first commercial scientific computer sold by IBM and the company's first series-produced mainframe. It was announced publicly on 21 May 1952. Jerrier Haddad and Nathaniel Rochester designed and developed it, basing the machine on the IAS machine built at Princeton. The 701 stored its working data in 72 Williams tubes, giving 2,048 words of 36 bits, and could be expanded or later fitted with magnetic-core memory. Nineteen systems were installed, eight of them at aircraft companies and one at the Lawrence Livermore National Laboratory, where it sped up nuclear explosive calculations. Arthur Samuel's checkers program and John Backus's Speedcode ran on it. The 701 opened the IBM 700 and 7000 series, which stayed IBM's high-end line until the System/360 arrived in 1964; its successor was the IBM 704.