Operating System

Introduction to Operating Systems


Introduction to Operating Systems is one of the most important foundations in Computer Science. An Operating System (OS) acts as an interface between the user and computer hardware. It manages system resources, controls program execution, handles memory, files, devices, and ensures smooth functioning of the computer system.

Every modern device — laptops, smartphones, servers, ATMs, and smart TVs — uses an operating system. Common examples include Windows, Linux, macOS, Android, and iOS.


What is an Operating System?

  • An Operating System is system software that manages hardware and software resources.
  • It provides an environment for executing application programs.
  • It acts as an interface between the user and hardware.
  • Without an operating system, computers cannot function properly.
User
Operating System
Computer Hardware

Objectives of Operating System

  • To make the computer system convenient to use.
  • To manage hardware resources efficiently.
  • To improve system performance.
  • To provide security and protection.
  • To allow multitasking and resource sharing.

Convenience

Makes the system easier for users to interact with.

Efficiency

Ensures optimal utilization of hardware resources.


Major Functions of an Operating System

FunctionDescription
Process ManagementHandles creation and scheduling of processes.
Memory ManagementAllocates and manages system memory.
File ManagementOrganizes and controls files and directories.
Device ManagementControls input and output devices.
SecurityProtects system and user data.

Types of Operating Systems

Batch Operating System

Multiprogramming Operating System

Multitasking Operating System

Real-Time Operating System

Distributed Operating System

Mobile Operating System


Basic Structure of Operating System

The Operating System sits between hardware and application programs. It provides services that help applications communicate with hardware.

User
Application Programs
Operating System
Hardware

System Calls

System calls provide communication between user programs and the operating system.

Examples of System Calls
  • File handling
  • Process creation
  • Memory allocation
  • Input and output operations
  • Communication between processes

Kernel and Shell

  • Kernel: Core part of the operating system responsible for managing hardware resources.
  • Shell: Interface through which users interact with the operating system.
User
Shell
Kernel
Hardware

Advantages of Operating System

  • Efficient hardware utilization
  • Better user convenience
  • Supports multitasking
  • Provides security and protection
  • Improves overall system performance

Summary

Operating Systems are the backbone of modern computing systems. They manage hardware resources, execute programs, provide security, and make computers convenient and efficient to use. Understanding Operating Systems is essential for advanced computer science, system programming, networking, and cybersecurity.

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Chapter I: Introduction to Operating Systems

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