Patent US 5,752,264

A hierarchical cache architecture that reduces traffic on a main memory bus while overcoming the disadvantages of prior systems. The architecture includes a plurality of level one caches that are of the store through type, each level one cache is associated with a processor and may be incorporated into the processor. Subsets (or "clusters") of processors, along with their associated level one caches, are formed and a level two cache is provided for each cluster. Each processor-level one cache pair within a cluster is coupled to the cluster's level two cache through a dedicated bus. By configuring the processors and caches in this manner, not only is the speed advantage normally associated with the use of cache memory realized, but the number of memory bus accesses is reduced without the disadvantages associated with the use of store in type caches at level one and without the disadvantages associated with the use of a shared cache bus.