Cache

Cache is a special memory subsystem in which frequently used data values are duplicated for quick access. A memory cache stores the contents of frequently accessed RAM locations and the addresses where these data items are stored. When the processor references an address in memory, the cache checks to see whether it holds that address. If it does, the data is returned to the processor; if it does not, a regular memory access occurs. A cache is useful when RAM accesses are slow compared with the microprocessor speed, because cached memory is faster than main RAM memory. There are three types of cache: L1 (Level 1): This is cache memory that is actually part of the processor chip; L2 (Level 2): L2 cache has the same purpose as L1 cache, but is usually not integrated into the processor. L2 cache is traditionally made of SRAM and in socket 7; L3 (Level 3): Level 3 cache is now the name for the extra cache built into motherboards between the microprocessor and the main memory. What was once L2 cache on motherboards now becomes L3 cache when used with microprocessors containing built-in L2 caches