CPU Cache Explained - What is Cache Memory?

DRAM vs. SRAM: The Foundation of CPU Cache00:00:00

The video begins by explaining that computers use two types of memory: DRAM (Dynamic RAM) and SRAM (Static RAM). DRAM, used in RAM modules, relies on capacitors that require constant refreshing with electricity to store data. SRAM, in contrast, doesn't need constant refreshing, making it significantly faster and more expensive. SRAM is the type of memory utilized in CPU cache.

What is CPU Cache and Why is it Important?00:00:52

CPU cache is the CPU's internal memory, designed to store copies of frequently accessed data and instructions from RAM. The CPU checks this faster cache first before resorting to the slower main RAM. This process significantly speeds up computer performance by reducing bottlenecks, as CPUs have become so fast that they often wait for data from RAM. The CPU cache acts as a middleman to feed data to the CPU faster, improving overall efficiency and performance at a lower cost than making all RAM as fast as cache.

The Three Levels of CPU Cache00:02:34

CPU cache is categorized into three levels: Level 1 (L1), Level 2 (L2), and Level 3 (L3). L1 cache, located directly on the processor, is the fastest. If data isn't found in L1, the CPU checks L2 cache. If still not found, it moves to L3 cache. Only after checking all three cache levels does the CPU access the slower main RAM.

Characteristics of Each Cache Level00:03:47

In earlier computers, L2 cache was on a separate chip, but in modern CPUs, all cache levels are on the processor. L1 cache is the fastest and smallest. L2 cache is larger than L1 but not as fast. L3 cache is the largest but not as fast as L2. L3 cache is often shared among all CPU cores, unlike L1 and L2, which are dedicated to individual cores.