Structure of Operating System

Back to Operating Systems
Arjit Sharma
01 Min

An operating system (OS) is a structured system that manages hardware and software resources to run programs efficiently.

Core Components of an OS

structure-of-os

The OS is built from key components, each with a specific function:

  • Kernel: The heart of the OS, controlling hardware, managing tasks, and handling system calls.
  • Process Management: Schedules running programs, ensure fair CPU time allocation and preventing conflicts.
  • Memory Management: Allocates and tracks RAM for processes, preventing programs from accessing each other’s memory.
  • File Systems: Organizes data on storage devices (e.g., hard drives) using formats like ext4 (Linux) or NTFS (Windows).
  • Input/Output (I/O): Manages communication with devices like keyboards, disks, or network cards, ensuring data flows correctly.

System Calls in Action

system-calls

System calls allow user applications to interact with the OS. When a program needs to read a file, allocate memory, or create a process, it makes a system call to request OS services. For example:

  • open() → Accesses files
  • fork() → Creates a new process
  • read() → Retrieves data from storage

These calls act as bridges between user applications and the OS kernel.

User Mode and Kernel Mode

user-kernel-mode

Modern OS architectures operate in two modes to ensure security and stability:

  • User Mode – Applications run with restricted access, preventing direct control over hardware.
  • Kernel Mode – The OS has full access to system resources, handling memory management, task scheduling, and I/O operations.

Conclusion

The OS provides a structured environment, ensuring efficient resource management, security, and smooth interaction between hardware and software.

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