Introduction to Operating System


Introduction to Operating Systems


An Operating System is a software that is responsible for controlling the operation of a computer system.
The OS acts as an intermediary between users and the computer hardware, enabling users to interact with the system and utilize its resources effectively.

Functions of an Operating System:

Resource management: Allocation and utilization of system resources such as CPU, memory, storage, and devices.
Process management: Creation, scheduling, and termination of processes (running programs) and allocation of resources to them.
Memory management: Allocation and deallocation of memory to processes and handling virtual memory.
File system management: Organizing and managing files on storage devices, controlling access and permissions.
Device management: Interacting with hardware devices, providing device drivers for communication between software and hardware.
User interface: Providing a means for users to interact with the computer system, such as command-line interface (CLI) or graphical user interface (GUI).
Network management: Facilitating network communication and managing network resources.
Security and protection: Implementing measures to protect the system from unauthorized access and ensuring data security.
Error handling: Detecting and handling errors and exceptions during program execution or device interactions.

Different Types of Operating Systems:

Based on Processing Method:

  1. Batch Operating System: A batch operating system does not interact directly with the computer. Instead, an operator groups similar jobs with the same requirements into batches. The system sorts and executes these batches, optimizing resource utilization. Batch operating systems are suitable for repetitive tasks, such as payroll systems or generating bank statements.
  2. Time-sharing Operating System: Time-sharing operating systems enable multiple users to simultaneously access and use a single system. Each user is allocated a time slice, known as a quantum, during which they can execute their tasks. Time-sharing systems rapidly switch between user tasks, giving the illusion of simultaneous execution. These systems are also called as multitasking systems.
  3. Multiprocessing Operating System: Multiprocessing operating systems utilize multiple processors or CPUs to execute tasks. This approach enhances system performance by parallelizing the workload. If one processor fails, the system can continue running using the remaining processors. However, multiprocessing operating systems can be more complex due to coordinating multiple processors.
  4. Multitasking Operating System: Multitasking operating systems allow the execution of multiple tasks simultaneously. These tasks may belong to a single user or multiple users. Preemptive multitasking involves the operating system preemptively allocating time slices to different tasks, ensuring fair execution. Cooperative multitasking relies on tasks voluntarily yielding control to the operating system, which requires cooperation from running tasks.
  5. Real-time Operating System: Real-time operating systems prioritize the completion of tasks within strict time constraints. Hard real-time systems have critical deadlines that must be met, such as in air traffic control or medical systems. Soft real-time systems have less stringent time constraints, such as multimedia applications. Real-time operating systems require precise timing and fast response to events.
  6. Distributed Operating System: Distributed operating systems consist of interconnected computers communicating over a shared network. Each computer in the network possesses its own memory and CPU, forming a loosely coupled system. These systems allow remote access to files and software on other connected devices, enabling distributed computing and resource sharing.

Based on User Interface:

  1. Command-Line Interface (CLI): A Command-Line Interface is a text-based user interface where users interact with the computer system by typing commands into a command prompt or terminal. In a CLI, users enter specific commands along with arguments and parameters to perform tasks or execute programs. The system responds with text-based output, providing information or indicating the results of the executed command. Examples of CLI-based operating systems include MS-DOS, Unix-based systems (Linux, macOS Terminal), and Windows Command Prompt.
  2. Graphical User Interface (GUI): A Graphical User Interface is a visual interface that allows users to interact with the computer system using graphical elements such as windows, icons, menus, and buttons. GUI provides a more intuitive and user-friendly environment compared to a CLI, enabling users to perform tasks by pointing, clicking, and manipulating visual elements. Examples of GUI-based operating systems include Microsoft Windows, macOS, various Linux distributions with desktop environments (Ubuntu with GNOME or KDE).

Based on Mode of User:

  1. Single-User Operating System: A Single-User Operating System is designed to support and cater to the needs of a single user at a time.These operating systems are typically found on personal computers and workstations used by individuals.
    • Only one user can log in and use the system at any given time.
    • The system resources are dedicated to serving the needs of the single user, allowing them full control and utilization of the resources.
    • User management is relatively simple, as there is only one user account to manage.
    • These operating systems often provide a personalized environment, allowing users to customize settings, preferences, and desktop configurations according to their needs and preferences.

    Examples of Single-User Operating Systems include Microsoft Windows (e.g., Windows 10), macOS, and various Linux distributions designed for personal use (e.g., Ubuntu Desktop).

  2. Multi-User Operating System: A Multi-User Operating System is designed to support multiple users simultaneously, allowing them to access and utilize the system concurrently. These operating systems are commonly found on servers, mainframes, and timesharing systems where multiple users need to access and share system resources.
  • Multiple users can log in and use the system concurrently, each with their own user account and associated privileges.
  • System resources are shared among multiple users, and the operating system manages resource allocation to ensure fair and efficient utilization.
  • User management features are provided to create and manage multiple user accounts, set access permissions, and control user privileges.
  • These operating systems facilitate resource sharing, allowing users to share files, applications, and other system resources with other authorized users on the same system.
Examples of Multi-User Operating Systems include various UNIX and Linux distributions (such as Ubuntu Server, Red Hat Enterprise Linux) and mainframe operating systems like IBM z/OS.

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