Page Replacement Algorithm Simulator

A Python/Jupyter Notebook project for the Operating Systems Lab assignment. It simulates FIFO, LRU, and Optimal page replacement and compares their page faults, hits, hit ratio, and fault ratio.

Features

• Accepts comma-separated or space-separated integer page references.
• Validates input and frame count.
• Shows step-by-step frame contents, Hit/Fault, and replaced page.
• Calculates page faults, page hits, hit ratio, and fault ratio.
• Compares FIFO, LRU, and Optimal on identical input.
• Includes manual tracing, Belady's anomaly experiment, and custom-string analysis.

Files

• Page_Replacement_Simulator.ipynb — notebook with explanations, implementation, sample outputs, and assignment answers.
• page_replacement.py — standalone Python source code.
• Project_Report.pdf — brief report.
• Assignment_Answers.md — manual tracing and Part C answers.
• screenshots/ — sample execution screenshots.

Run the project

Jupyter Notebook

1. Install Python 3 and Jupyter Notebook (or use Google Colab).
2. Open Page_Replacement_Simulator.ipynb.
3. Run the cells from top to bottom.
4. In the interactive cell, enter a page string such as 1 2 3 1 4 2 5 and frame count 3.

Run as a Python script

python page_replacement.py

Example input:

Enter page reference string (comma or space separated): 1 2 3 1 4 2 5
Enter number of frames: 3

Algorithm overview

• FIFO: evicts the page that has been in memory the longest.
• LRU: evicts the page whose most recent use is farthest in the past.
• Optimal: evicts the page whose next use is farthest in the future (or that will never be used again). It is a benchmark because future references are not known in advance in a real operating system.

Sample result

For reference string 1 2 3 1 4 2 5 with 3 frames:

• FIFO: 5 faults, 2 hits
• LRU: 6 faults, 1 hit
• Optimal: 5 faults, 2 hits

Ratios are calculated as hits / total references and faults / total references.

Tie-breaking rule

For Optimal, if multiple pages are never referenced again, the page appearing first in the frame list is replaced, as specified in the assignment.

Author

Name: Anuj Prajapati Roll No.: BTE25DTA000008