This book introduces the concepts and methodologies employed in designing a system-on-chip (SoC) based around a microprocessor core and in designing the microprocessor core itself. The principles of microprocessor design are made concrete by extensive illustrations based upon the ARM. The aim of the book is to assist the reader in understanding how SoCs and microprocessors are designed and used, and why a modern processor is designed the way that it is. The reader who wishes to know only the general principles should find that the ARM illustrations add substance to issues which can otherwise appear somewhat ethereal; the reader who wishes to understand the design of the ARM should find that the general principles illuminate the rationale for the ARM being as it is. Other microprocessor architectures are not described in this book. The reader who wishes to make a comparative study of architectures will find the required information on the ARM here but must look elsewhere for information on other designs.