Cache Memory
O Cache memory is a very fast memory located on or close to the CPU. O It is used to speed up processing by storing the data and instructions that may be needed next by the CPU in handy locations. O Although it can access materials in RAM relatively quickly, it can work much faster if it places the most urgently needed materials into cache memory. O When cache memory is full and the CPU calls for additional data or a new instruction, the system overwrites as much data in cache memory as needed to make room for the new data or instruction.
Cache Memory
O This allows the data and instructions that are most likely still needed to remain in cache memory. O Cache memory today is usually internal cache (built right into the CPU chip). O In the past, some cache memory was external cache (located close to, but not inside, the CPU).
Cache Memory
O Cache memory level numbers indicate the order in which the various caches are accessed by the CPU when it requires new data or instructions. O Level 1 (L1) cache (which is the fastest type of cache but typically holds less data than other levels of cache) is checked first, followed by Level 2 (L2) cache, followed by Level 3 (L3) cache if it exists.
Cache Memory
O If the data or instructions are not found in cache memory, the computer looks for them in RAM, which is slower than cache memory. O If the data or instructions cannot be found in RAM, then they are retrieved from the hard drive, an even slower operation. O Typically, more cache memory results in faster processing. O Most multi-core CPUs today have some cache memory (such as a L1 and L2 cache) dedicated to each core. O They may also use a larger shared cache memory (such as L3 cache) that can be accessed by any core as needed.