OS purposes: resource management and the extended virtual computer; historical development. Processes: critical sections and mutual exclusion, semaphores, monitors, classical problems, deadlock; process scheduling. Input and Output: hardware and software control. Memory management: multi-programming; swapping; virtual memory, paging and symbolic segmentation; File System: operations, implementation, performance. Operating System Security and Protection mechanisms: protection domains, access lists, capability systems, principle of minimum privilege, security threats and attacks, encryption, and authentication