🚀 Operating Systems Notes

A structured and comprehensive guide covering key concepts, system architecture, CPU scheduling, memory management, process synchronization, and more. This repository is perfect for students, software engineers, and anyone preparing for technical interviews.

📌 Syllabus

1️⃣ Basics

• 🔹 Introduction to Operating Systems
• 🔹 Types of Operating Systems
• 🔹 Functions of Operating System
• 🔹 Real-Time Systems & Tasks
• 🔹 Multitasking vs. Multithreading vs. Multiprocessing
• 🔹 Computer Memory (RAM & ROM)
• 🔹 32-bit vs. 64-bit OS
• 🔹 Boot Process & UEFI vs. BIOS

2️⃣ System Structure

• 🔹 Microkernel & Monolithic Kernel
• 🔹 Kernel I/O Subsystem
• 🔹 System Calls & Process Resource Limits
• 🔹 Dual-Mode Operations (Privileged vs. Non-Privileged Instructions)

3️⃣ CPU Scheduling

• 🔹 Process Lifecycle & PCB
• 🔹 CPU Scheduling Types (Preemptive & Non-Preemptive)
• 🔹 Scheduling Algorithms:
  • ✅ FCFS (Convoy Effect)
  • ✅ Shortest Job First (SJF)
  • ✅ Longest Remaining Time First (LRTF)
  • ✅ Round Robin Scheduling
  • ✅ Priority Scheduling (Preemptive & Non-Preemptive)
  • ✅ Multilevel Queue & Feedback Queue
  • ✅ Lottery Scheduling
  • ✅ Multiple-Processor Scheduling

4️⃣ Process Synchronization

• 🔹 Critical Section Problem
• 🔹 Interprocess Communication (IPC):
  • Shared Memory, Message Queues, Signals
• 🔹 Semaphores & Mutex
• 🔹 Classic Problems:
  • ✅ Producer-Consumer Problem
  • ✅ Dining Philosophers
  • ✅ Readers-Writers Problem
  • ✅ Sleeping Barber Problem
  • ✅ Priority Inversion & Inheritance

5️⃣ Deadlock

• 🔹 Deadlock Detection & Recovery
• 🔹 Deadlock Prevention & Avoidance
• 🔹 Banker’s Algorithm
• 🔹 Resource Allocation Graph (RAG)
• 🔹 Deadlock in Distributed Systems

6️⃣ Processes & Threads

• 🔹 Threads (User-Level vs. Kernel-Level)
• 🔹 Multithreading Models & Benefits
• 🔹 Zombie Processes & Prevention
• 🔹 Remote Procedure Call (RPC)

7️⃣ Memory Management

• 🔹 Memory Hierarchy & RAM Types
• 🔹 Memory Allocation Techniques:
  • Buddy System, Fixed & Dynamic Partitioning
  • Paging & Segmentation
• 🔹 Page Replacement Algorithms:
  • ✅ LRU, Optimal, LFU, Clock Policy
• 🔹 Thrashing Prevention & Memory Virtualization

8️⃣ Disk Management

• 🔹 File Systems & Unix File System
• 🔹 Disk Scheduling Algorithms (SSTF, Spooling, Buffering)
• 🔹 Free Space Management

9️⃣ Miscellaneous

• 🔹 Introduction to UNIX & Linux Commands
• 🔹 Shell Scripting Basics
• 🔹 Process States & Transitions in UNIX
• 🔹 crontab in Linux
• 🔹 Advanced find Command Usage

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📖 How to Use This Repository

1. Clone the repository:

   git clone https://github.com/yourusername/Operating-Systems-Notes.git