Operating System Layers

Operating System Layers

1. User Interface

   • The User Interface allows the user interacts with the computer using input devices (keyboard, mouse etc.) and output devices (computer screen). There are two types of User Interfaces, Graphical User Interfaces (GUI) and Command Line Interface (CLI).
   • Command Line Interface (CLI) is a user interface in which the user has to type in the commands. An example of this is windows Command Prompt (cmd) e.g. C: > dir Windows /p Graphical User Interfaces (GUI) is the typical User Interfaces that uses a what is called a WIMP (Windows Icons Menus Pointers), this also includes dialog boxes, radio buttons, check boxes, list boxes, scrollbars etc.  

2. File Management

   • Logical Drivers
     • A/B Drive (Floppy Disk), C Driver (Hard Drive) and D Driver (CD Drive)
   • Bootlable Drivers
     • Boot Sequence
   • File Locking
     • File Hierarchy
       • Logical Structure

3. Input/Output

   • Character and Block I/O
   • Interrupts
     • Interrupt Service Routine

4. Memory Management

   • Swap Files
     • Thrashing
   • Physical Memory (Memory Space) and Virtual Memory (Address Space)
   • Paging
     • Segmentation
       • Combination
   • Memory Mapping (between Addresses)
     • Page Table
       • Page Number
   • Subalocators

5. Kernel

   • Pre-Emptive Multitasking (OS sqeduels tasks) and Co-operative (Relinquishes task at appropriate time)
   • Process (Waiting, Running, Blocked, Terminated)
   • Masked Interrupts
   • IPC Mechanics (DDE, OLE, File Mapping (File Attachments) , (non)-named pipes, RPC)