Cache Memory
Computer and other digital systems may have thousands or millions of bytes of internal memory (RAM and ROM) that store programs and data that the CPU needs during normal operation. Normally, this would require that all of the internal memory have and operating speed comparable to that of the CPU in order to achieve maximum system operation. In many system it is not economical to use high-speed memory devices for all of the internal memory. Instead, system designers use a block of high-speed cache memory, this caches memory block is the only block that communicates directly with the CPU high speed; program instruction and data are transferred from the slower cheaper internal memory to the cache memory when they are needed by the CPU the success of cache memory depends on many complex factors, and some system will not benefit from using cache memory.