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UoL CS Notes

Operating Systems Overview

COMP124 Lectures

Operating Systems

The purpose of operating systems is to:

  • Turn base hardware into a usable machine.
  • Make efficient use of available resources, particularly when they are shared.

Abstract of Components

flowchart TD
uci[User Command Interface] <--> mm[Memory Manager] & fm[File Manager] & dm[Device Manager] & pm[Processor Manager]
mm <--> fm & dm & pm
fm <--> dm
fm <--> pm
dm <--> pm

Everything can talk to every other thing.

All but the UCI are the four essential managers of every OS, each working with the others to perform its task:

  • Memory Manager
  • Processor Manager
  • Device Manager
  • File Manager

Network functions were not always an integral part of an OS.

  • A Network Manager can be added to handle networking tasks.
  • User Command Interface
    • How users interact with the OS by issuing commands.

Manager Functions

Each subsystem manager must perform the following tasks:

  • Continuous monitoring of resources.
  • Enforcement of policies that determine who gets what resources, when they get them and how much.
  • Allocation of resource when it is appropriate.
  • De-allocation of resources when finished.