LOCAL MEMORY READOUT SYSTEM

PROBLEM TO BE SOLVED: To improve the performance of a local memory by prereading data out of the local memory, and outputting the preread data when the address of data preread at a next read request matches the read address and immediately completing the read address. SOLUTION: A processor 1 initiates memory read actuation to an I/O 2 and when the data bus width of the local memory 4 is as wide as the data width of an I/O bus and the access time of the local memory 4 is longer than that of the I/O bus, data of a next address is preread between accesses of I/O data. When the addresses matches each other by next access, the access is immediately ended with the preread data. When the bus width of the local memory 4 is narrower than the data width of the I/O bus, data of the next address and the address right after it are preread again and when the address matches each other, the access is ended with the two preread data.