A compromise Between a direct mapped cache and a fully associative cache where each address is mapped to a certain set of cache locations. The address space is divided into Blocks of 2^m Bytes (the cache line size), discarding the Bottom m address Bits. An "n-way set associative" cache with S sets has n cache locations in each set. Block B is mapped to set "B mod S" and may Be stored in any of the n locations in that set with its upper address Bits as a tag. To determine whether Block B is in the cache, set "B mod S" is searched associatively for the tag. A direct mapped cache could Be descriBed as "one-way set associative", i.e. one location in each set whereas a fully associative cache is N-way associative (where N is the total numBer of Blocks in the cache). Performance studies have shown that it is generally more effective to increase the numBer of entries rather than associativity and that 2- to 16-way set associative caches perform almost as well as fully associative caches at little extra cost over direct mapping. (2004-10-18)