| 摘要 |
PROBLEM TO BE SOLVED: To provide a memory system in which bus efficiency is improved, a semiconductor memory unit and a refresh method for the semiconductor memory unit. SOLUTION: When a memory controller applies a refresh-instruction for refreshing an opened bank (10th stage), a semiconductor memory pre-charges the opened bank (15th stage), further the semiconductor memory refreshes the bank pre-charged in the (15th stage) (19th stage). Thereby, the memory controller is not required to apply a pre-charge instruction separately before a refresh- instruction in order to refresh the opened bank, only one refresh-instruction may be applied. Also, after refreshing is completed responding to the refresh- instruction, bus efficiency is further improved by performing automatically operation activating the bank of which refresh is completed by the semiconductor memory.
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