Java Operating Systems Core Concepts Simulations

This repository contains key simulations and implementations covering foundational topics in Operating Systems, developed for an undergraduate CS course. The projects are designed to demonstrate a practical understanding of resource management, scheduling, and virtual memory.

📁 Project Structure

Directory	Content	Key Concepts Demonstrated
01_CPU_Scheduling	FIFO, Round Robin, EDF simulation code.	Process Management, Time Slicing, Preemption, Context Switching.
02_Page_Replacement	FIFO, LRU, Second Chance simulation code.	Virtual Memory, Paging, Page Fault Minimization, Frame Management.
03_RealTime_Scheduling	Rate Monotonic Scheduling (RMS) implementation.	Real-Time Systems, Static Priority, Task Periodicity, Schedulability.

1. CPU Scheduling Algorithms

Implementation: 01_CPU_Scheduling/Main.java

Simulates non-preemptive (FIFO) and preemptive (Round Robin) CPU dispatching, along with conceptual classes for a real-time scheduler (EDF).

• Algorithms: FIFO, Round Robin (RR), Earliest Deadline First (EDF) Concept.
• Focus: Calculating execution order, and modeling time slice behavior.

2. Virtual Memory: Page Replacement Algorithms

Implementation: 02_Page_Replacement/Main.java

Compares the performance of three classic page replacement policies by measuring the number of Page Faults for a given reference string and a fixed number of memory frames.

• Algorithms: First-In, First-Out (FIFO), Least Recently Used (LRU), Second Chance (SC).
• Focus: Minimizing Page Faults, understanding the cost/benefit trade-offs of replacement strategies.

3. Real-Time Scheduling: Rate Monotonic

Implementation: 03_RealTime_Scheduling/Main.java

Simulates a static-priority scheduling environment where task priorities are determined by their rate (inverse of their period).

• Algorithm: Rate Monotonic Scheduling (RMS).
• Focus: Ensuring critical tasks meet their deadlines, modeling preemption based on priority derived from task period.

🚀 How to Run

Each folder contains a Main.java file which can be compiled and run independently:

# Example for CPU Scheduling
cd 01_CPU_Scheduling
javac Main.java
java Main

The program will prompt for input parameters required for the simulation.