Cache Memory - Types & Levels of Cache Memory:

Cache Memory :

A CPU cache is a cache memory used by the CPU of a computer to reduce the average time to access main memory. The Cache is a smaller & faster memory that stores copies of the data from the most frequently used central memory location. Cache Memory holds data and instructions that are transferred to and from the main memory. When a disk is read, a large block of data is moved into the cache. Thus, slow disk access is avoided again and again by using cash memory.

Most of the new microprocessors have the Cache memory added in the CUP chip itself to speed up the process even further. even on these CPUs with built-in internal Cache, you an add external Cache.

Levels of Cache Memory :

Level 1 (L1) :

Level 1 Cache is built into the actual processor core. It is a piece of RAM, typically 64 or 128 Kb in size, which operates at the same clock frequency as the rest of the CPU.

Level 2 (L2) :

The level 2 Cache is normally much larger (and unified), such as 256, 512, or 1024 KB. the Purpose of the L2 Cache is to constantly read slightly larger quantities of data from RAM so that these are available to the L1 cache.

CPU Type	L2 Cache
Pentium K5, K6	External, on the motherboard
Pentium Pro	Internal, in the CPU
Pentium II, Athlon	External, in a module close to CPU
Celeron (1st generation)	None
celeron (later gen.), Pentium III, Athlon XP, Duron, Pentium 4	Internal, in the CPU

Level 3 (L3) :

The L3 cache is larger but also slower than L1 and L2, its size is between 1MB to 8MB in Multicore processors, each core may have separate L1 and L2, but all cores share a common L3 Cache. L3 cache double speed than the RAM.

Note: Cache memory is a very high-speed memory built into the processor and it is used between the main memory (RAM) and the processor.

*Learn more about : Cache Memory Performance & Concept of Mapping