Divided into four parts OS concepts, practice, architecture of contemporary operating systems and projects on OS - this fourth edition offers a comprehensive treatment of operating systems. While Unix and Windows are covered in good detail, this edition emphasizes changes that have occurred in design technology and pattern of use. The new edition, comes with focus on Linux kernel, VxWorks and operating systems for handheld systems. The chapter on IO has been updated to include some preferred bus interfaces and protocols. The book is intended for the undergraduate students of computer science and engineering, computer applications, and information technology.