Operating System

Operating System(OS)

 What is OS
Goals of OS
Views of OS

Today we will be learning about OS

OPERATING SYSTEM

An OS is a program that acts as an intermediate between computer users and computer hardware.
It also provides basis for application program.

Goals of OS

  • To execute programs.
  • To solve user problems easily.
  • To make the computer easy to use.
Hardware provides basic computing resources
  • CPU
  • Memory
  • I/O devices
Application program defines how the resources are used to solve computing problems of the user.
Ex: work process, spread sheet, compilers.
The OS control and coordinates the use of hardware among various application program for various users.

There are two OS views
  1. User view
  2. System view
User view

• Most users use a PC consisting of a monitor, keyboard and system unit.
The OS is designed mostly for ease of use.
-Some attention is given to the performance.
-No attention given to resource utilisation.
-The OS is optimised for the single user experience.

• Some users use a terminal connected to a mainframe or minicomputer
-OS is designed to maximize resource utilisation and to assure that no individual user takes more than his/her fair share.

• Some users use a workstation connected to network
-The users have dedicated resources such as networking and services.
-The OS is designed to compromise between 
-individual usability
-resource utilisation

• Some users use a handheld computer 
- the OS is designed mostly for individual usability.
-performance per unit of battery life is a very important factor. 

System Views

• An OS as a resource allocate
- Resources used to solve a computing problem, CPU time, memory space, file storage space, I/O devices.
- OS manages and allocates the above resources to programs and the users.

• An OS is a control program
- OS is needed to control.
- operation of I/O devices.
- execution of user programs to prevent errors. 

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