This edition provides students with a complete kernel of a multiprocess operating system (KMOS), supplying them with a ready-made real time operating system to put theory into practice. Hardware foundation and support for operating systems is discussed throughout. The book includes a detailed explanation of input/output programming, as well as case studies, which allow students to relate their theoretical knowledge and design experience to widely used contemporary operating systems such as UNIX, DOS and OS/2. New to this edition are examples from commercial operating systems; chapters on security, multiprocessors and distributed systems; and KMOS is now written in object-oriented Turbo Pascal.