| abstract |
(57) [Summary] A dynamic memory requires a refresh operation to retain information in a memory cell. As a result, contention occurs between access to the dynamic memory other than refresh (external access) and access for refresh, and performance degradation occurs. A dynamic memory is pipelined, and a pipeline frequency (CLK) of the pipeline dynamic memory (PDRAM) is changed to an external access frequency (CLK). 1), and an access necessary for a refresh operation is performed on the pipeline dynamic memory in an empty slot of the pipeline of the pipeline dynamic memory (timing at which external access is not always issued). [Effect] The refresh operation for the internal dynamic memory is an internal operation, and there is no need to consider the refresh at the external access timing. Therefore, the usability is good and the operation speed is high. |