Operating Systems

Unit 1: Introduction to Operating Systems

Understand the engine that runs every computer — from your Android phone to ISRO's mission-critical servers.

⏱️ 5 hours theory + 3 hours lab | 💰 ₹3,000–₹10,000/month | 📝 30 MCQs (Bloom's Mapped)

💼 Jobs: Linux Admin (₹4–7 LPA) | Systems Engineer (₹5–8 LPA) | DevOps Intern (₹15K–25K/month)

🎯 Interview Fit: TCS / Infosys / Wipro / Amazon / Google India

Section A

Opening Hook — The Invisible Manager Behind Every System

🚆 When IRCTC Crashed on Tatkal Day — And 12 Lakh Users Screamed

January 2023. 10:00 AM sharp. 12 lakh Indians hit the IRCTC Tatkal booking page simultaneously. Within seconds, the servers choked. Pages froze. "502 Bad Gateway" errors flooded screens. ₹200 crore worth of tickets — stuck in limbo.

Behind the scenes, the Operating System was the first to break. Thousands of processes competed for CPU time. Memory ran out as each user session consumed RAM. File handles exceeded limits as the database opened millions of connections. The OS couldn't schedule processes fast enough, couldn't manage memory efficiently, and couldn't handle the I/O bottleneck of simultaneous disk reads.

The fix? IRCTC upgraded to a distributed system with better CPU scheduling, virtual memory tuning, and process management. The engineers who redesigned this? They all understood Operating Systems inside-out.

Could YOU have prevented this crash? After this chapter, you'll understand exactly what went wrong — and how to fix it.

🇮🇳 IRCTC🇮🇳 ISRO PSLV🇮🇳 Aadhaar/UIDAI🇮🇳 Zerodha🇮🇳 Paytm🇮🇳 CoWIN

ISRO's Mars Orbiter Mission (Mangalyaan) runs on a real-time OS that manages 5 scientific instruments, communication systems, and navigation — all with just 15 MB of storage. That's less memory than a single WhatsApp photo. The OS makes it possible.

Section B

Learning Outcomes — Bloom's Taxonomy Mapped

Bloom's Level	Learning Outcome
🔵 Remember	Define an operating system and list its 5 core functions
🔵 Remember	Name and describe 7 types of operating systems with real-world examples
🟢 Understand	Explain the difference between kernel mode and user mode with the IRCTC analogy
🟢 Understand	Describe monolithic, layered, microkernel, and modular OS architectures
🟡 Apply	Use Linux commands (`uname`, `ps`, `top`, `strace`) to explore OS internals
🟡 Analyze	Compare OS architectures and evaluate which suits different Indian system needs
🟠 Evaluate	Judge why IRCTC chose Linux over Windows for their production servers
🟠 Create	Set up and configure a Linux VPS for a small business on DigitalOcean/Hostinger