This text aims to provide a firm foundation in the principles and concepts of operating systems design and discuss major issues, as well as to show how several operating systems have implemented these concepts. It covers all major topics of operating systems, including memory management, I/O processing, concurrent processing, auxiliary storage management, and scheduling. There is also a chapter on queuing theory and a chapter with four case studies: MS-DOS, UNIX, VMS, and MVS. Additional case studies are presented at the end of each chapter.