Operating Systems

Definition: An Operating System (OS) is a system software that acts as an intermediary between the computer hardware and the computer user. It provides a user interface and manages hardware resources such as the CPU, memory, disk drives, and input/output devices. The OS ensures efficient execution of programs and provides services for application software. It is the foundational software that enables the hardware to perform tasks required by users and applications.

Functions of an Operating System:

1. Process Management: The OS manages processes in the system, which includes the execution of processes, multitasking, scheduling, and process synchronization.
2. Memory Management: It controls and coordinates memory usage, managing both primary (RAM) and secondary (disk storage) memory. It ensures that programs and processes do not interfere with each other’s memory.
3. File System Management: The OS provides mechanisms for storing, retrieving, and organizing files on storage devices. It also manages access permissions and file protection.
4. Device Management: It manages hardware devices like printers, disks, and display units. The OS provides device drivers that allow communication between the hardware and the software.
5. Security and Access Control: The OS ensures data security, user authentication, and authorization for resource access. It protects against unauthorized access and malicious attacks.
6. User Interface (UI): Provides the user with an interface to interact with the system (either command-line or graphical).
7. Networking: It manages network communication, data transfer, and ensures network security and connectivity.
8. System Performance Monitoring: Monitors and optimizes system performance, including CPU utilization, memory usage, and disk space.

Types of Operating Systems:

Batch Operating System:

• • Definition: A batch OS processes jobs in batches without user interaction.
  • Characteristics:
    • Jobs are grouped together into batches based on type or priority.
    • No direct interaction between users and the system during job execution.
    • Commonly used in environments where high volumes of repetitive tasks are required.
  • Example: IBM’s OS/360.

Multitasking (Time-sharing) Operating System:

• • Definition: A multitasking OS allows multiple tasks to run concurrently by rapidly switching between them, giving the illusion of parallel execution.
  • Characteristics:
    • Supports time-sharing where each task gets a slice of the CPU’s time.
    • Multiple users can interact with the system at the same time.
    • Increases system efficiency by sharing CPU time.
  • Example: UNIX, Linux, Windows.

Multiprocessing Operating System:

• • Definition: A multiprocessing OS is designed to run on computers with multiple processors (CPUs), allowing the system to handle multiple processes simultaneously.
  • Characteristics:
    • Can execute multiple processes at the same time, utilizing multiple CPUs.
    • More efficient in terms of performance as tasks are distributed across processors.
    • Enables parallel processing.
  • Example: Linux, Windows Server.

Distributed Operating System:

• • Definition: A distributed OS manages a group of independent computers and presents them as a unified system to the users.
  • Characteristics:
    • The OS ensures that the resources across different machines are used effectively.
    • It hides the complexity of the network from users and applications.
    • Each node can function independently but shares resources like memory and processing power.
  • Example: Google’s Android OS (distributed in nature), Amoeba OS.

Network Operating System:

• • Definition: A network OS manages and coordinates networked computers and resources in a networked environment.
  • Characteristics:
    • Provides networking services, such as file sharing, network security, and communication between machines.
    • Enables devices to communicate over a network, and supports client-server architectures.
    • Can be used in both small-scale and large-scale network environments.
  • Example: Novell NetWare, Windows Server.

Real-Time Operating System (RTOS):

• • Definition: A real-time OS is designed to meet the timing constraints of real-time applications, where the system’s response time must be within a specific period.
  • Characteristics:
    • Guarantees the execution of critical tasks within a certain time frame.
    • Prioritizes tasks based on urgency and deadlines.
    • Used in embedded systems, medical devices, aerospace, and robotics.
  • Example: VxWorks, QNX, RTEMS.

Mobile Operating System:

• • Definition: A mobile OS is specifically designed to run on mobile devices such as smartphones, tablets, and wearable devices.
  • Characteristics:
    • Provides essential mobile features such as touch-screen functionality, battery management, and mobility.
    • Supports wireless communication protocols like Wi-Fi, Bluetooth, and cellular.
    • Focused on efficient resource management for mobile hardware.
  • Example: Android, iOS, Windows Phone.

Single-User, Single-Task Operating System:

• • Definition: These operating systems are designed to manage a single user and a single task at a time.
  • Characteristics:
    • No multitasking or time-sharing features.
    • Generally used in simple computing environments or embedded systems.
    • Not suited for complex applications requiring multitasking.
  • Example: MS-DOS, early versions of Apple’s macOS.

Single-User, Multi-Tasking Operating System:

• • Definition: These OS allow a single user to run multiple tasks simultaneously.
  • Characteristics:
    • Provides multitasking for a single user by allowing different programs to run concurrently.
    • Common in personal computers and laptops.
    • Supports features like memory management, task scheduling, and window management.
  • Example: Windows, macOS.

Embedded Operating System:

• • Definition: An embedded OS is designed to run on embedded systems and specific hardware.
  • Characteristics:
    • Optimized for performance and resource constraints.
    • Highly specialized and customized for particular applications like IoT devices, appliances, automotive systems, etc.
    • Generally real-time, responsive, and lightweight.
  • Example: Embedded Linux, FreeRTOS, Android Things.