Learn: Cache - Why the CPU Needs It

Welcome!Welcome back! You've already learned about the CPU, its components, and how it processes instructions. Today, we're focusing on cache and why the CPU relies on it to work efficiently.

What is Cache?Cache is a small, fast memory located close to the CPU. It stores frequently used data and instructions to reduce the time needed to access them. This speeds up processing and prevents delays caused by accessing slower main memory (RAM).

Why Does the CPU Need Cache?The CPU needs cache because accessing data from RAM can take too long during processing. Cache holds data that the CPU is likely to need next, making operations quicker and more efficient. Without cache, the CPU would waste time waiting for data from RAM.

Levels of CacheCache is divided into levels based on speed and size: L1 (smallest and fastest), L2 (larger but slower than L1), and L3 (largest and slowest of the three). These levels work together to optimise data access for the CPU.

How Cache WorksWhen the CPU needs data, it first checks the cache. If the data is there (a cache hit), it can be accessed quickly. If not (a cache miss), the CPU must fetch the data from RAM, which takes longer.

Cache Size and CPU PerformanceThe size of the cache affects CPU performance. A larger cache can store more data, reducing the chance of cache misses. However, increasing cache size can make it slower and more expensive, so a balance is necessary.

Review Time!Well done! You've learned about cache, its levels, and how it helps the CPU work efficiently. Let's review the key concepts.