Operating System Overview and Components

Operating System Overview

• Operating system (OS) is software that makes computers user-friendly, manages resources efficiently and acts as an interface between hardware, software, and users.
• The core of the operating system is the Kernel, which manages all hardware and software interactions.
• Key roles of an operating system include managing resources, controlling program execution, and handling user interactions.

Operating System Components

• Essential Subsystem Managers:
  • Command Interpreter System (User Interface): Enables communication between user and operating system.
  • Memory Manager: Manages computer's main memory (RAM).
  • Processor Manager: Allocates Central Processing Unit (CPU).
  • I/O Device Manager: Monitors I/O devices like printers, ports, and disk drivers.
  • File Manager: Tracks and manages files stored on the system.
  • Secondary-Storage Manager: Manages storage of files on hard drives.
  • Network Manager: Enables communication and resource sharing across networks.
  • Security Manager: Ensures system security and controls access to resources for users and programs.

Operating System Types

• Batch Operating System: Executes programs in batches, without direct user interaction.
  • Improves resource utilization and cost-effectiveness but lacks user interaction and has limited error handling capabilities.
• Multiprogramming Operating System: Allows multiple programs to run concurrently on a single processor.
  • Improves resource utilization, user experience, and I/O operations efficiency.
• Time-Sharing Operating System: Allows multiple users or processes to share resources like CPU, memory, and peripherals simultaneously.
  • Creates the illusion of exclusive access for each user while sharing resources efficiently using time slicing.
• Multiprocessing Operating System: Utilizes multiple processors (CPUs) to run more than one program or process concurrently.
  • Can improve system performance with various architectures:
    • Symmetric Multiprocessing (SMP): Uses identical processors sharing resources, offering simple management.
    • Asymmetric Multiprocessing (ASMP): Uses specialized processors with dedicated resources, requiring more complex management.
• Network Operating System: Manages and facilitates communication and coordination between computers on a network.
  • Provides features like file sharing, print sharing, device management, security, remote access, and centralized administration.
• Distributed Operating System: Designed for systems where independent computers work together as a single entity, regardless of their geographical location.
  • Enables efficient management of resources and processes across a network.

Operating System Evolution

• Batch Processing (Early 1950s): Jobs were submitted on punch cards processed sequentially, improving CPU utilization but lacking user interaction.
• Multiprogramming and Time-Sharing (1960s): Multiple programs were executed concurrently improving CPU utilization, and time-sharing further refined this by allowing multiple users to share CPU time.
  • Introduction of DOS/360, UNIX, and CP/M.
• Personal Computers and GUIs (1980s - 1990s): Increased use of personal computers (PCs) demanded user-friendly interfaces.
  • Graphical User Interfaces (GUIs) emerged, enabling non-technical user interaction.
  • MS-DOS, Microsoft Windows, and SunOS marked this era.
• Modern Operating Systems (Present): Characterized by increased network capabilities, integration with mobile devices, and focus on security and cloud computing.