A processor containing a cache memory having its storage capacity enlarged while suppressing area increases is provided. The processor includes an SRAM (Static Random Access Memory) cache memory and a DRAM (Dynamic RAM) cache memory of a large storage capacity. The SRAM cache memory and the DRAM cache memory are coupled to the processor through a processor bus. The SRAM cache memory and the DRAM cache memory transfer data through an internal transfer bus provided separately from the processor bus and having a larger width.

A method and a memory controller for controlling a DRAM including a memory plane formed with an array of memory cells and at least two cache registers. An access request including a page address, a column address, a write or read order, a possibly data to be written is received. The page address of the current request is compared with the page address of the preceding request and, if they are different, the controller stores the current request page in one non-used of the cache registers, preferably that which has not been used last.

A high-speed, static random access memory (SRAM) compatible, high availability memory array and method employing synchronous dynamic random access memory (DRAM) in conjunction with a data cache and separate data read and write registers and tag blocks. The inclusion of separate data read and write registers allows the device to effectively operate at a cycle time limited only by the DRAM subarray cycle time. Further, the inclusion of two tag blocks allows one to be accessed with an externally supplied address and the other to be accessed with a write-back address, thus eliminating the requirement for a single tag to execute two read-modify write cycles in one DRAM cycle time.