Computer Notes: Operating System – A Brief Overview

Operating System – A Brief Overview

Introduction -

• An Operating System is a program that manages the computer hardware. It provides a basis for the application programs. An operating system acts as an interface between user of a computer and the hardware of the computer. Operating System is important for every modern computing devices i.e. mobile phones, personal computer, super computer. 

Example of Operating System –

• MS DOS, WINDOWS 7, UNIX, Ubuntu, WINDOWS 10 etc.

Structure of Operating System - 

A computer system is divided into four components i.e. the hardware, the operating system, the application programs and the users.

• The Hardware- This part consists of Central Processing Unit (CPU), memory and input/output devices. It provides basic computing resources. 
• The Operating System- It includes file management, process management, memory management and I/O control routines. It provides the means for the proper use of resources of the computer system.
  
• Application Programs- It defines the ways in which the resources are used to solve the computing problems of the users.
  
• Users- The users sit at the terminal connected to the mainframe or minicomputer. These users share the resources and may exchange information.
  

Objectives of the Operating System -

• Operating System makes the computer more user-friendly and convenient. 
• It allows the resources of the computer system which must be used in efficient manner.
  
• It permits the effective development, test and the new functions of the system without indulging with the service.
  

Features of Operating System -

• Device Management - It keeps the track of all devices.  It decides that which of the processes gets device. It also determines the place and timing. 
• Memory Management- It also tracks the primary memory and allocates it when a process or program requests for it.
  
• File Management - It allocates and withdraws resources and decides its recipient.
  
• Processor Management - It allocates CPU or the processor to a process when it is required.
  
• Security- It prevents the unauthorized access by the third party to the programs and data by providing password and other security measures.
  
• It controls the system performance and records the delay between request and response.
  
• It coordinates between Users and Software.
  

Types of Operating System-

 Batch Operating System -

• The user does not interact directly with computer. 
• It transfers control from one job to the next automatically.
   
• Operator sorts the programs into batches and run the batches when the computer is available.
  

Multi-Programmed Operating System-

• It keeps several jobs in memory simultaneously. 
• It increases CPU utilization by organizing the jobs in such a way that the CPU always has one job to execute.
  

Time-Sharing Operating System-

• It is a logical extension of multi-programming operating system. 
• It executes multiple jobs by switching among them, but the users can interact with each program while running.
  
• It provides direct communication between user and system.

Single User Operating System-

• It can be used on a single computer and is developed for a single user at any given time.

Multi User Operating System-

• It allows more than one user on multiple computers to access the single system with one operating system on it.

Real Time Operating System-

• It is used when a there is a rigid time requirement. It has well-defined fixed time constraints. 
• Time interval is required in this operating system to process. 
• It is of two types, I.e. hard real-time system and soft real-time system. 
• It functions properly if it returns the result correctly within the time constraints.