What is processor cache

[Tumo]

Hello friends,

I am newbie and i don't have much more idea about computer parts and peripherals, today when i went to college my friends where discussing about processor cache and how does it works etc to me everything was going up from my mind they even try to explain me about processor cache but was not able to understand it properly. Can anyone provide me some information about it. Thanks in Advance.

[JamesB]

Normally a processor cache is a two-level cache, in which level 1 cache (L1) is smaller and faster; while level 2 cache (L2) is slightly slower, but anytime faster than the main memory. The size of the cache line is usually larger than the size of the usual access requested by a CPU instruction, which ranges from 1 to 16 bytes. Each location in each memory also has an index, which is a unique number used to refer to that location. The index for a location in main memory is called an address.L1 cache is divided into two parts , instruction cache and data cache. Instruction cache stores the set of instructions that are required by the CPU for computing; while the data cache stores the values that are required for current execution. L2 cache is responsible for loading the data from the main memory.

[Demetrius]

According to me when a Processor needs to read or write a location in main memory, it first checks whether that memory location is in the cache. Normally this is done by comparing the address of the memory location to all tags in the cache that might contain address. If the finds that the memory location is in the cache, then we say that cache hit has being done or else we say that cache has miss it. In the case of a cache hit, the processor immediately reads or writes the data in the cache line. The proportion of accesses that result in a cache hit is known as the hit rate, and is a measure of the effectiveness of the cache.

[memo_nn]

Imagine this. You work on desk doing some research, you are stuck with paper, so you put some in the drawers, but your most importmant data is on the desk. So cache memory is the area where you put your most frequently used data so it's easier and faster to find that you can work faster, drawers are like ram, you put there the data that you don't use frequently, so biger your desk (cache memory) the faster you work. Hope you understood now