由于cache比主存小很多，为了保证CPU执行指令时可正确访问存储单元，需将用户程序中的逻辑地址转换为运行时由机器直接寻址的物理地址，这一过程称为地址映射,所以必须使用一种机制将主存地址定位到cache中，就构成了地址映射，因为需求不同，也就导致了不同的地址映射方式，主要有直接映射、组相联映射、全相联映射三种地址映射方式-Because cache than main memory small many, to guarantee CPU implementation instruction can correct access storage unit, required will user program in the of logic address conversion for run Shi by machine directly addressing of physical address, this a process called address map, so must using a mechanism will main memory address positioning to cache in the, on constitute has address map, because demand different, also on led has different of address map way, main has directly map, and group phase joint map, and full phase joint map three species address map way