Introduction to Operating Systems

Introduction

• A computer operating system (OS) is a software that manages computer hardware and software resources.
• It acts as an intermediary between the user and the computer hardware.
• It provides services like file management, process management, memory management, and device management.

Key Functions of Operating Systems

• Process Management:
  • Manages the execution of programs (processes) by allocating resources like CPU time and memory.
  • Handles process creation, termination, scheduling, and synchronization.
  • Implements mechanisms to prevent conflicts between concurrent processes.
• Memory Management:
  • Allocates and deallocates memory to programs.
  • Manages virtual memory, which allows programs to use more memory than physically available.
  • Handles paging and segmentation to improve memory utilization and efficiency.
• File Management:
  • Organizes and manages files and directories.
  • Provides functionalities for creating, deleting, reading, writing, and manipulating files.
  • Ensures access control and security of files.
• Device Management:
  • Controls and manages hardware devices (e.g., printers, keyboards, mice).
  • Provides a standardized interface for interacting with these devices.
  • Handles device drivers to facilitate communication between OS and hardware.
• Security:
  • Protects the system from unauthorized access and malicious software.
  • Implements access control mechanisms, authentication methods (passwords, biometrics) to ensure secure operations of the OS.
• User Interface:
  • Provides a user-friendly way for users to interact with the system (e.g., command-line interface, graphical user interface).
  • Allows users to execute commands, interact with files, and run applications.

Types of Operating Systems

• Batch Operating Systems:
  • Execute jobs in batches without direct user interaction.
• Time-Sharing Operating Systems:
  • Allow multiple users to share the system resources concurrently.
  • Each user appears to have their own dedicated system.
• Real-time Operating Systems (RTOS):
  • Designed for applications requiring precise and predictable response times (e.g., industrial control systems, embedded systems).
  • Provides guaranteed response times to critical events.

Common Operating Systems

• Windows: Developed by Microsoft, primarily used for personal computers and desktops.
• macOS: Developed by Apple, primarily used for Apple computers.
• Linux: An open-source OS, widely used for servers, embedded systems, and desktops.
• Android: A mobile operating system developed by Google.
• iOS: A mobile operating system developed by Apple.

Key Concepts

• Kernel: The core of the operating system.
  • Manages system resources in real-time.
• Shell: Provides a command-line interface for interacting with the kernel.
• User Mode: Processes running with limited access.
• Kernel Mode: Processes running with full access to system resources.

Modern Operating System Trends

• Cloud computing: Operating systems are increasingly being designed to support cloud environments.
• Virtualization: Enables running multiple operating systems on a single physical machine.
• Mobile computing: Operating systems are optimized for mobile devices and their specific needs.
• Security: Continued focus on protecting systems from threats and vulnerabilities.
• Open-source movement: Continued growth in open-source operating systems like Linux and other distributions.