Instructor 1957-60; assistant professor 1960-64; associate professor 1964-67; full professor 1967; MIT Class of 1922 Professor of Electrical Engineering, 1968-71; associate dean for student affairs, 1965-67; associate provost, 1969-70; Dean of the School of Engineering, 1970-71; chancellor, 1971-80; President of MIT 1980-90; Chairman of the MIT Corporation, 1990-97