For one- and two-semester Operating Systems courses (in the most recent ACM/IEEE curriculum) that universities offer to juniors, seniors and graduate Computer Science students. The text goes beyond the standard coverage in operating systems courses with key chapters on multiprocessing, networking, distributed systems, performance, and security. The text features extensive, up-to-the-minute case studies on the latest versions of Linux (2.6) and Microsoft Windows XP. An abundance of charts, diagrams, illustrations and exercises (both with and without solutions) is included.