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OS Concepts And Design
[^] CSc 422
[Chapter 1][Chapter 2][Chapter 3][Chapter 4]
[Chapter 1: Introduction to Operating Systems] [Chapter 1: Computer Hardware Review] [OS Concepts And Design]
  1. Types of operating system.
    1. Mainframe.
      1. Batch processing. Legacy apps.
      2. OS/390. Unix variants.
      3. Often multiple instances under VM.
    2. Server. Unix/Linux or Windows.
    3. Multi-processors.
      1. Multiple CPUs.
      2. Now a common case with multiple cores.
      3. Effects O/S design.
    4. PC Operating System.
      1. Mostly Windows variants and MacOS.
      2. (Except for us non-conformists.)
    5. Hand-held/mobile.
      1. He mentions Symbian and Palm OS.
      2. Now more often the smart phone OSes: iOS, Android.
    6. Sensor node. Don't know how common these actually are. TinyOS
    7. Real-time.
      1. Industrial processes.
      2. Vehicle control.
      3. Hard and soft.
    8. Smart card.
  2. Concepts and Abstractions.
    1. Processes.
      1. Identity and ownership.
      2. Communication and control.
      3. A process operates in an address space.
    2. Address space.
    3. Files.
      1. Files and directories.
      2. Hierarchy.
      3. Permissions.
      4. Opening files and file handles. fileread1.cpp
      5. Some files have special behavior.
        1. Directories (folder) are special files.
        2. Some files represent physical devices.
    4. Protection.
      1. Hardware modes give the O/S secure control.
      2. OS then implements other restrictions.
        1. File permission.
        2. Memory controls.
    5. I/O.
      1. O/S performs all I/O; forbids user.
      2. Users ask the O/S for service.
      3. See above.
    6. Shell (command interpreter). Text or graphical.
  3. System Calls.
    1. Process creation, destruction and control.
    2. I/O of any kind.
    3. Creation of files and directories.
    4. Hello using write library call.
    5. i386 assembly Hello, World!.
    6. There are many system calls. See the textbook.
  4. Structure.
    1. Monolithic. Collection of functions, any of which can call another.
    2. Layered system.
      1. Functions are collected into layers.
      2. Functions only call to the next layer down.
      3. Provides some organization. May have hardware to enforce it.
    3. Microkernels
      1. Functions are removed from the kernel to minimize it.
      2. Instead, provided by local server processes.
      3. Process communicate by passing messages.
      4. Client-server version distinguishes processes by type.
      5. Robust, flexible.
        1. Crashed service processes may be restarted.
        2. Variations of basic services w/o modifying the kernel.
      6. Limited commercial use for performance reasons.
    4. Virtual machines.
      1. Software simulates hardware; O/S runs on the simulated hardware.
      2. Early: IBM on the 360/370 hardware.
        1. When the guest kernel executes a privileged instruction, hardware traps.
        2. The trap handler simulates the effect of the privileged instruction on the simulated machine.
      3. Presently, on PC hardware.
      4. Type 1 and 2.
      5. VM is difficult on i386 hardware.
        1. Privileged instructions in user mode are ignored instead of trapped.
        2. Use a form of JIT translation.
        3. Add a kernel module (modify to host kernel) to add support.
      6. Paravirtulization.
        1. Modify the guest OS to behave differently when run under another OS.
        2. Remove the privileged instructions and let it make syscalls like everyone else.