Cache Memory Simulator

🗂️ 🏃 ⚡

Think of Cache like your desk. RAM is the big filing cabinet across the room. Your CPU always checks the desk first — if the file is there (Cache HIT ✅), it's instant! If not (Cache MISS ❌), it has to walk to the cabinet and bring it back.

Pattern:

Replace:

🖥️ CPU

Requesting block:

—

↓

HIT

What's happening?

Choose a pattern and press Next Request to start!

Watch if the CPU finds data in the fast cache (✅ HIT) or has to fetch it from slow RAM (❌ MISS).

Performance

✅ Hits

❌ Misses

Hit Rate

Requests

Hit Rate: 0%

Cache Memory 4 slots (ultra fast)

⚡ 1 nanosecond access

—

RAM (Main Memory) 16 blocks (slow)

🐢 100 nanoseconds access

Request Log

Waiting for first request...

Upcoming Requests

Step 1 of 7

Welcome!

Let's learn how cache memory works.

⚡

What Is Cache Memory?

In the simplest possible terms

📁✏️ → 🗄️

Your desk vs the filing cabinet.

Imagine you're working at an office:

🗂️

Desk (Cache) — Room for only 4 files. But grabbing one takes 1 second.

🗄️

Cabinet (RAM) — Holds 16 files. But you must walk across the room — takes 100 seconds!

💡

Smart idea: keep files you use often on your desk! Then most of the time you don't need to walk to the cabinet.

This is exactly what your computer does. The CPU (you) checks cache (desk) first. If the data is there → instant! If not → slow trip to RAM (cabinet) and then it brings the data back to cache for next time.

Two things can happen when the CPU requests data:

✅

CACHE HIT

The data IS in cache.
CPU gets it instantly.
⚡ 1 nanosecond!

❌

CACHE MISS

Data NOT in cache.
Must fetch from RAM.
🐢 100× slower!

The Hit Rate is the % of requests that found data in cache. A good program has 90%+ hit rate because it tends to reuse the same data repeatedly.

🤔 Cache is tiny — only 4 slots. What happens when it's full and we need new data?

The computer must evict (remove) one old block to make room. Two popular policies:

LRU

Least Recently Used — Remove the block that hasn't been used for the longest time. Like throwing away the oldest file on your desk.

FIFO

First In, First Out — Remove the block that was added to cache first. Like a queue — the first one in leaves first.

LRU is usually smarter because recently used data is more likely to be needed again.

🌍 Cache memory is everywhere — it's why modern computers feel fast:

💻

Your CPU — Modern CPUs have L1, L2, and L3 cache layers. L1 is the fastest (but only ~64 KB). L3 is slower but holds several MB.

🌐

Web Browsers — When you visit a website, images and files are cached on your disk so the page loads instantly next visit!

📺

Video Streaming — Netflix pre-buffers (caches) the next few minutes of video so playback stays smooth.

🎮

Games — Game engines cache textures in GPU memory (VRAM) so they render frames at 60+ FPS without reading from disk every frame.