| 摘要 |
PROBLEM TO BE SOLVED: To enable transferring data efficiently in a SDRAM(synchronous dynamic random access memory) by performing appropriately refresh processing of SDRAM. SOLUTION: A SDRAM 1 is accessed from blocks 3, 4 through a mediation block 2. The mediation block 2 informs proper or improper of access to the blocks 3, 4 depending on a high/low state of a busy signal based on access request from the blocks 3, 4. When access request is not performed for the prescribed period, a request signal is outputted to a refresh pulse generating circuit 5. Receiving a request signal, the circuit 5 generates a refresh pulse. In the mediation block 2, a refresh command of the SDRAM 1 is issued based on a refresh pulse and refresh processing of the SDRAM 1 is performed. As refresh processing is performed while selecting a time in which the SDRAM 1 is not accessed, a bus of the SDRAM 1 can be efficiently utilized. |
