John L. Hennessy was born in 1953 and grew up in Long Island, New York. He earned his bachelor's degree in electrical engineering from Villanova University (1973) and his master's (1975) and PhD (1977) in computer science from SUNY Stony Brook.
Hennessy joined Stanford University's faculty in 1977 as an assistant professor of electrical engineering. In 1981, he drew together researchers to focus on a computer architecture known as RISC (Reduced Instruction Set Computing), a technology that would revolutionize the computer industry by increasing performance while reducing cost. During his sabbatical year in 1984, he cofounded MIPS Computer Systems to produce commercial RISC microprocessors. It was a risky concept at the time, but RISC technology now appears in devices as varied as supercomputers and smartphones.
Hennessy, who has lectured and published widely, is the coauthor (with David Patterson) of two well known textbooks on computer architecture and design.
In October 2000, he was inaugurated as Stanford University's 10th president. Hennessy is a member of the National Academy of Engineering and the National Academy of Sciences, and a fellow of the American Academy of Arts and Sciences, the ACM, and the IEEE.