This textbook provides coverage of the fundamental concepts which make up the foundation of operating systems and also gives practical experience with a fully functioning instructional operating system called NACHOS. This edition also features new chapters on the history of the operating systems and on computer ethics, as well as a further case study on WindowsNT. Memory management, including modern computer architectures and file system design and implementation are also covered. Common operating systems (MS-DOS, OS/2, Sun OS5 and Macintosh) are used throughout to illustrate concepts and provide examples of performance characteristics.