This easy-to-read textbook provides an introduction to computer architecture, focusing on the essential aspects of hardware that programmers need to know. Written from a programmer’s point of view, Essentials of Computer Architecture, Third Edition, covers the three key aspects of architecture: processors, physical and virtual memories, and input-output (I/O) systems. This third edition is updated in view of advances in the field. Most students only have experience with high-level programming languages, and almost no experience tinkering with electronics and hardware. As such, this text is revised to follow a top-down approach, moving from discussions on how a compiler transforms a source program into binary code and data, to explanations of how a computer represents data and code in binary. Additional chapters cover parallelism and data pipelining, assessing the performance of computer systems, and the important topic of power and energy consumption. Exclusive to this third edition, a new chapter explains multicore processors and how coherence hardware provides a consistent view of the values in memory even though each core has its own cache. Suitable for a one-semester undergraduate course, this clear, concise, and easy-to-read textbook offers an ideal introduction to computer architecture for students studying computer programming.