What is an Operating System, history of operating system, operating system zoo; process concept, process scheduling, inter-process communication; threads; CPU scheduling, basic concepts, scheduling criteria, scheduling algorithms; process synchronization, the critical section problem, semaphores, monitors, classical synchronization problems; deadlocks, avoidance, prevention, detection; memory management, physical and virtual memory, swapping, allocation, paging, segmentation; file systems, access methods, directory structure, file sharing and protection; security, authentication, intrusion detection, encryption.