This classic textbook, long considered essential reading by students and practitioners of computer design, celebrates its 20th year by focusing on new platforms—personal mobile devices and warehouse-scale computers—and new architectures—multicore and GPUs. This new edition covers these two areas in depth, where much of the excitement and innovation is now happening, while remaining true to its original mission of demystifying computer architecture through an exploration of cost-performance-energy trade-offs and an emphasis on good engineering design.