Karnaugh worked at Bell Labs (1952 to 1966), developing the Karnaugh map (1954) as well as patents for PCM encoding[1] and magnetic logic circuits and coding.[2][3][4][5] He later worked at IBM's Federal Systems Division in Gaithersburg (1966 to 1970) and at the IBM Thomas J. Watson Research Center (1970 to 1994), studying multistage interconnection networks.[6]