Nathaniel Rochester joined IBM in November 1948 as an associate engineer. He coordinated the work of the Poughkeepsie Engineering Planning Group, and in cooperation with the Planning Group from the Applied Science Division, he developed firm specifications for the Defense Calculator. He developed outstanding planning and system specifications, including arithmetic functions and logical operations, for the design of the machine. Rochester’s ability to prepare programs and test these programs on paper saved much valuable time. He led the effort to prepare utility sub-programs to facilitate the use of the IBM 701 by IBM and its clients. He was named an IBM Fellow in 1967.