MULTI-WAY SET ASSOCIATIVE CACHE SYSTEM IN WHICH THE NUMBER OF LINES PER SET DIFFERS AND LOADING DEPENDS ON ACCESS FREQUENCY

A set associative cache system in a computer system having a lower memory is provided with a plurality of cache memory sets. A cache data memory contains a plurality of cache lines to store data in units of blocks corresponding to data stored in the lower memory. A cache tag memory stores lower memory addresses for data stored in the cache lines. The plurality of cache memory sets have different numbers of cache lines. A read/write section reads out data stored in the lower memory into the plurality of cache lines and writing data in the plurality of cache lines back to the lower memory.