Leader of a top-secret program to develop high-speed deciphering machines to crack Nazi codes during World War II, Mumma was a pioneering figure in early computing. He served as the Business Manager of National Cash Register Company's Electrical Research department, then part of the U.S. Navy's National Computing Machine Laboratory for designing and manufacturing state-of-the-art code-breaking machinery. An NCR laboratory in Dayton produced 120 machines called Bombes that, beginning in the fall of 1943, were instrumental in cracking a variety of German codes.
Mumma was the top assistant to Joseph R. Desch, the chief of NCR's Electrical Research department who designed the Bombes. He took over as head of the laboratory when Desch suffered a nervous breakdown in November 1944, and remained in that position until the end of the war. He was a holder or co-holder of a number of early patents in the design and construction of the first analog fixed-program computer.
Mumma retired from NCR in 1969 as head of Peripheral Equipment Engineering, leaving behind a legacy of 36 patents in his name.
