This contains nice notes on operating systems which covers: Processes, Synchronization, and Scheduling, Introduction to Processes, Dispatching and Creating Processes, Entering and Exiting the Kernel, Independent and Cooperating Processes, Synchronization, The Too Much Milk Problem, Semaphores and Producer/Consumer Problem, Semaphore Example: Readers and Writers, Monitors, Message Systems, Semaphore Implementation, Scheduling and CPU Scheduling, Deadlock, Memory Management and Virtual Memory, Storage Allocation, Sharing Main Memory, Base and Bounds, Segmentation, Paging, Translation Buffers and Inverted Page Tables, Virtual Memory, Page Faults, Page Selection and Replacement, Clock Algorithm, Thrashing, Working Sets, Virtual Machines (PDF file), I/O and File Systems, Files, Disk Management, Unix and DEMOS Disk Allocation, Directories, Windows (NT) File System, File System Crash Recovery, Disk Scheduling, Protection and Security, Protection and Security, Security Abuses, Security Improvements and Encryption.