The aim of this text is to provide a foundation for understanding, evaluating and comparing the design principles incorporated in widely-used, state-of-the-art microprocessors and minicomputers. Practical examples are drawn primarily from the Motorola MC68000 family, but also from the DEC VAX-11 and other architectures, enabling students to understand real designs and the trade-off between speed, memory, and cost. Programming examples are mainly given using the Pascal language. Excellent coverage is given of the operating system interface and of RISC and multiprocessors. Some knowledge of programming languages and an understanding of computer hardware at an introductory level is required. Due to its flexible structure, the text can be used in courses with a variety of emphases.