When the first edition of this book appeared in 1987, it caused something of a small revolution in the way operating systems courses were taught. Until then, most courses just covered theory. With the appearance of MINIX, many schools began to have laboratory courses in which students examined a real operating system to see how it worked inside. We consider this trend highly desirable and hope it continues.

It its first 10 years, MINIX underwent many changes. The original code was designed for a 256K 8088-based IBM PC with two diskette drives and no hard disk. It was also based on UNIX Version 7 As time went on, MINIX evolved in many ways: it supported 32-bit protected mode machines with large memories and hard disks. It also changed from being based on Version 7, to being based on the international POSIX standard (IEEE 1003.1 and ISO 9945-1). Finally, many new features were added, perhaps too many in our view, but too few in the view of some other people, which led to the creation of Linux. In addition, MINIX was ported to many other platforms, including the Macintosh, Amiga, Atari, and SPARC. A second edition of the book, covering this system, was published in 1997 and was widely used at universities