Receiving his Ph.D. from the University of California, Berkeley, in 1963, Wirth was Assistant Professor of Computer Science at Stanford University (1963–67) and Professor of Informatics at ETH Zurich (1963–99). He was the sole or a major designer of several programming languages and operating systems, most significantly Pascal but also including Modula, Modula 2, Oberon, and PL/360. See also stepwise refinement.