What are Operating Systems? or What is an Operating System?

Introduction

Operating System is an interface between User and Hardware and the relation is shown in the picture below:

Things handled by the Operating System

Resource Allocating

When we have many programs running simultaneously, we are supposed to allocate:

1. CPU to some of them.
2. Memory to some of them.
3. Input Output to some of them.

These works are done by resource allocator.

NOTE: Sometime resources are sharable but sometime they are not.

Acts as a Manager

It typically manages following things:

1. Memory
   • Amount of memory you have?
   • How much memory is allocated?
   • What percentage of memory is free?
2. Processes
   • The states are managed by OS.
3. Files
   • All the system files present on the secondary storage is managed by OS.
   • Plus any other files from other media source are also managed by Operating System.
4. Security
   • If a process is given some resource, then at the same time any other process or program cannot use the same resource.