Preface to the First Edition A computer is like a violin. You can imagine a novice try- ing first a phonograph and then a violin. e laer, he says, sounds terrible. at is the argument we have heard from our humanists and most of our computer scientists. Com- puter programs are good, they say, for particular purposes, but they aren’t flexible. Neither is a violin, or a typewriter, until you learn how to use it. —Marvin Minsky, “Why Programming Is a Good Medium for Expressing Poorly-Understood and Sloppily-Formulated Ideas” “Tis  S  I  C P” the entry-level subject in computer science at the Massachuses Institute of Technology. It is required of all students at  who major in electrical engineering or in computer science, as one-fourth of the “common core curriculum,” which also includes two subjects on circuits and linear systems and a subject on the design of digital systems. We have been involved in the development of this subject since 1978, and we have taught this material in its present form since the fall of 1980 to between 600 and 700 students each year. Most of these students have xxi