ABSTRACT
Memory can be thought of as being arranged in a hierarchy, which consists of various cache levels and the main memory. As discussed in Chapter 15, the level-1 caches are situated on the CPU chip; the level-2 cache is either on the CPU chip or very close by; and level-3 caches, where they are used in multiprocessor systems, are usually connected to the system bus. The objective of these caches, particularly level-1 and level-2, is to keep the CPU busy and thus improve performance by minimizing the dependency on the relatively slower accesses to main memory, usually called RAM. This topic describes recent memory technologies used in these caches and in main memory.
