Operating System – Detailed Explanation

Operating System

Introduction to Operating System

An Operating System (OS) is the most important system software of a computer. It acts as an interface between the user and the computer hardware. Without an operating system, a computer cannot perform any useful work.

The operating system manages hardware resources, controls the execution of programs, and provides services to users and applications. Examples of operating systems include Windows, Linux, macOS, Android, and iOS.

Definition

An Operating System is a collection of programs that manages computer hardware resources and provides common services for computer programs.

Objectives and Functions of an Operating System

Objectives

  • Convenience – Makes the computer easy to use
  • Efficiency – Uses hardware resources effectively
  • Ability to evolve – Allows development of new system functions

Main Functions

  • Process Management
  • Memory Management
  • File System Management
  • I/O Device Management
  • Secondary Storage Management
  • Security and Protection
  • User Interface

Process Management

A process is a program that is currently being executed. The operating system manages multiple processes simultaneously.

Responsibilities

  • Creating and deleting processes
  • Scheduling processes
  • Synchronization of processes
  • Handling deadlocks
  • Inter-process communication

Process States

  • New
  • Ready
  • Running
  • Waiting
  • Terminated

CPU Scheduling Algorithms

  • First Come First Serve (FCFS)
  • Shortest Job First (SJF)
  • Priority Scheduling
  • Round Robin Scheduling

Memory Management

Memory management refers to managing primary memory (RAM). The operating system keeps track of memory usage and allocation.

Functions

  • Memory allocation and deallocation
  • Tracking memory usage
  • Memory protection
  • Virtual memory management

Techniques

  • Contiguous Memory Allocation
  • Paging
  • Segmentation
  • Virtual Memory

Virtual memory allows the execution of large programs even when physical memory is insufficient.

5. File System Management

A file is a collection of related information stored on secondary storage. The operating system organizes files into directories.

Functions

  • Creating and deleting files
  • Reading and writing files
  • Directory management
  • File permission control

File Attributes

  • File name
  • Size
  • Type
  • Location
  • Protection

Types of File Systems

  • FAT
  • NTFS
  • ext4

Input/Output (I/O) Device Management

I/O device management controls input and output devices such as keyboard, mouse, printer, and disk drives.

Functions

  • Device control
  • Providing device drivers
  • Buffering and caching
  • Interrupt handling

A device driver allows the operating system to communicate with hardware devices.

Secondary Storage Management

Secondary storage includes hard disks, SSDs, and USB drives. The operating system manages disk space efficiently.

Responsibilities

  • Free space management
  • Storage allocation
  • Disk scheduling

Disk Scheduling Algorithms

  • FCFS
  • SSTF
  • SCAN
  • C-SCAN

Protection and Security

Protection ensures processes do not interfere with each other, while security prevents unauthorized access.

  • User authentication
  • Access control
  • Encryption
  • Firewall support

User Interface

Types

  • Command Line Interface (CLI)
  • Graphical User Interface (GUI)

Types of Operating Systems

  • Batch Operating System
  • Time-Sharing Operating System
  • Distributed Operating System
  • Network Operating System
  • Real-Time Operating System

Examples of Operating Systems

  • Windows
  • Linux
  • macOS
  • Android
  • iOS

Advantages of Operating System

  • Efficient use of hardware
  • User-friendly interface
  • Supports multitasking
  • Provides security

Conclusion

The operating system is the backbone of a computer system. It manages resources, provides security, and enables users to interact with hardware efficiently. Without an operating system, a computer cannot function.