Background - what is an operating system? an introduction to UNIX and MS-DOS; basics - introduction, overview of Operating System, the "process concept, hardware features, introduction to object orientation; User Interface - outline, system calls, command languages, job control languages, graphical user interface, system properties management; process management - basic concepts, process life cycle, scheduling, processes in UNIX, processes in Windows; memory management 1 - introduction, memory allocation methods; memory management 2 - virtual memory, virtual segmented systems, virtual machines; memory management 3 - protection and sharing, MS-DOS memory management, UNIX memory management, summary; input-output -organization of I/O software and hardware, UNIX I/O system, MS-DOS I/O system; file management 1 - general principles, system services; file management 2 - file management techniques, improving the performance of Disk systems; current processes 1 - basic principles, competing processes, UNIX features; concurrent processes 2 - deadlocks, interprocess communication; networks and distributed systems -introduction, networks, the Internet an World Wide Web, distributed systems; security - introduction, security - the nature of the threats, security techniques. appendices: introduction to the UNIX Shell; summary of MS-DOS commands. Answers to review questions; answers to selected test questions. Web references.