Unit 1 - Introduction to Operating Systems (OS) – Notes

Software:

• Software is a set of instructions or programs that tell a computer what to do.

Think of it like this:
If your computer is the body, software is the brain that gives it commands.

There are two main types:

1. Application Software – These are the programs you use every day, like:

   • Web browsers

   • Games or video players
     → They help you do specific tasks.

2. System Software – This runs in the background and helps the computer work properly:

   • The Operating System (like Windows, Linux, macOS).
     → It manages all the hardware and software so everything runs smoothly.

What is an Operating System?

An operating system is a piece of software that manages all the resources of a computer system,both hardware and software, and provides an environment in which the user can execute his/her programs in a convenient and efficient manner by hiding underlying complexity of the hardware and acting as a resource manager. by:

• Hiding hardware complexity

• Acting as a resource manager

Why Do We Need an OS?

What if there’s no OS?

1. Applications would become bulky and complex because:

   • Each app would need to include code to interact with hardware directly.

2. One app could monopolize resources.

3. No memory protection or isolation between programs.

What Is an OS Made Up Of?

An operating system is a collection of system software that includes utilities, libraries, kernel components, and device drivers.

Major Functions of an Operating System

• Access to Hardware: Manages CPU, memory, storage, and peripherals.

• User Interface: Acts as a bridge between user and hardware.

• Resource Management (also called Arbitration):

  • Memory, I/O devices, files, security, processes.

• Abstraction: Hides complex hardware operations.

• Protection & Isolation: Prevents one app from interfering with another.

• Execution Support: Facilitates running and managing applications.

OS in the System Architecture

Here’s a simplified system stack:

User
↑
Application Programs
↑
Operating System
↑
Computer Hardware

Summary

The operating system is a crucial component that ensures effective, secure, and reliable usage of a computer system. It simplifies user interaction with complex hardware and helps manage system resources efficiently.