Cache Memory

It is a small high speed and expensive memory present in between RAM and EPU.
The working speed of CPU is increasing day by day but the speed of its of its data provider(RAM) has fnot increased significantly. Cache is used in between these two devices to balance their speed and increased overall speed.
When CPU requireds any data or instruction, it searches them in the cache and used from the cache. its searches in the RAM. If the required contains are not available in the cash. The condition in which CPU finds data in the cache is known as hit and reverse condition is know as miss. The ratio of hit by miss impresent computer is arround 9:1.
Cache stores most frequently requirds data and instructions different levels of cache like L1,L2 and L3 are defined qand use to increase the processing speed. L1(level1) stores most frequently required data, L2(level two)f stores comparitevely less frequently used data and so on. When CPU frequireds any data its for searches the data in L1 cache then in L2 if not found L1 and similarly L3 and RAM.