Abstract: An information processing system has a plurality of modules, including a processor, a main memory and a plurality of I/O devices. A data cache comprises a cache data memory which is coupled to the processor which provides data to the processor in response to a load operation and for writing data from the processor in response to a store operation. A refill controller is coupled to the cache data memory for controlling the operation of the data cache in accordance with a specifiable policy. An external access controller is coupled to the cache data memory. The external access controller is coupled to an external memory bus, such that the contents of the cache data memory are accessible for read and write operations in response to read and write requests issued by the modules in the information processing system.