INPUT/OUTPUT BUFFER DEVICE AND MANAGEMENT METHOD THEREFOR

PROBLEM TO BE SOLVED: To improve the memory transfer performance by performing control so that data regarding DMA transfer are not held unnecessarily. SOLUTION: A block end detecting circuit 150 detects the final data of a block at the time of DMA transfer and blocks in an input/output buffer devices are invalidated through a control circuit 110, so blocks having small possibility of reuse are not left in the input/output buffer device 100, and can be released early. Further, a DMA end detecting circuit 170 detects data being the tail data of the DMA transfer and then blocks in the input/output buffer device 100 are invalidated through the control circuit 110, so even when a block is not accessed up to the final data, the input/output buffer device 100 can be made ineffective at the end of the DMA transfer. Therefore, the device is invalidated for every used block, so the blocks can be released at early stage and the device can effectively be utilized.