Overview

An Operating System (OS) is the boss. It manages the hardware (CPU, RAM, Disk) and lets applications (Chrome, Word) run without fighting each other.

Core Idea

The core idea is Abstraction. The OS hides the messy details of the hardware. You don’t need to know how to spin the hard drive to save a file; the OS does it for you.

Formal Definition

A program that acts as an intermediary between a user of a computer and the computer hardware.

Intuition

  • The Traffic Cop: The OS decides which program gets to use the CPU right now (Scheduling).
  • The Landlord: The OS decides which program gets which chunk of memory (RAM).
  • The Librarian: The OS organizes files on the disk (File System).

Examples

  • Linux: The open-source OS that runs the internet (and Android).
  • Windows: The dominant desktop OS.
  • macOS: Based on Unix.

Common Misconceptions

  • Misconception: It’s just the graphical interface (GUI).
    • Correction: The core is the Kernel, which is invisible. The GUI is just a program running on the OS.
  • Misconception: You can run any program on any OS.
    • Correction: Programs are compiled for specific OS APIs (System Calls).

Applications

  • Servers: Linux.
  • Embedded Systems: Real-time OS (RTOS) in your car’s brakes.

Criticism and Limitations

  • Bloat: Modern OSs are massive and complex, leading to bugs and security vulnerabilities.

Further Reading

  • Operating System Concepts by Silberschatz
  • Modern Operating Systems by Tanenbaum