Learn: Cache in Memory Hierarchy

Welcome!Welcome back! You've explored why computers need primary storage, and the roles of RAM and ROM. Today, we'll build on that to understand cache and why it speeds up memory access.

What is Cache?Cache is a small, very fast type of memory located close to the CPU. It temporarily stores frequently accessed data so the CPU can process it quickly without waiting for slower main memory (RAM).This speeds up performance because accessing cache is faster than accessing RAM.

How Does Cache Work?Cache works by storing data that the CPU uses repeatedly. When the CPU requests data, it first checks the cache. If the data is there, it’s called a cache hit. If it’s not, the CPU retrieves it from RAM, called a cache miss.Cache is organised in levels: L1 (smallest, fastest), L2 (larger, slightly slower), and sometimes L3.

Cache LevelsCache memory is divided into levels:L1 Cache: The smallest and fastest, located directly on the CPU.L2 Cache: Larger than L1, slower but still faster than RAM.L3 Cache: Even larger and slower, shared among cores in multi-core processors.Each level balances size, speed, and proximity to the CPU.

Cache vs RAMBoth cache and RAM store data temporarily, but cache is much faster and smaller than RAM. While RAM is the main working memory, cache is designed specifically to serve the CPU with the data it needs immediately.

Why Cache is LimitedCache is smaller than RAM because it is expensive to produce. Building very fast memory takes more resources, so manufacturers keep cache size small to balance cost and performance.

Review Time!Great work! You've learned about cache memory, how it works, and why it speeds up the CPU. Let’s review these concepts with a few questions.