Operating System

• Why do we need an OS?

  It allows the user to interact with the hardware.
• What are their OS functions?

  Memory Management, UI, Utility Programs and File Management.
• How does the OS multitask?

  The processor allocates a small amount of time to each process and cycles between tasks.
• Explain File Management?


  The OS adds an extension to the file name to load files into such as pptx.

  Also allows users to change details of files and delete them.
• What is WIMP?


  Windows,Icons, Menus and Pointers
• What is User Management?

  It allows multiple users to log-into the same computer whilst retaining each users different settings.
• Why are UIs important?


  Allows user to interact with the OS
• Scheduling


  The method an OS uses to ensure all processes get sufficient processor time.
• Round Robin


  CPU Scheduling algorithm used in OS for managing execution of multiple processes. Fixed amount of time and if the time is not finished it gets put to the back of the queue.
• First come first serve

  First job to arrive is dealt by CPU
• Shortest Job


  Shortest time first.

  However it is not good when running big problems.
• Shortest time remaining


  Scheduler estimates how long each process takes.
• Multilevel feedback queue

  Each queue has a different priority