The speed of CPU is extremely high comparedto the access time of main memory. Therefore the performanceof CPU decreases due to the slow speed of main memory. To minimize the mismatch in operating speed, a small memory chip is attached between CPU and Main memory whose access timeis very close to the processing speed of CPU. It is called CACHE memory. CACHE memories are accessed much faster than conventionalRAM. It is used to store programs or data currently being executed or temporary data frequently used by the CPU.So cache memory makes main memory to work faster and largerthan it really is. It is also very expensive to have bigger size ofcache memory and therefore it is available in limited capacity generally Kilo Bytes.