| 摘要 |
PROBLEM TO BE SOLVED: To improve the memory reading speed from a memory by dividing the data equivalent to single line of an ECC block by every prescribed word that excludes as much as possible the change of a row address in a reading mode and then arranging the divided data in order. SOLUTION: The data equivalent to 16 lines are written in an area equivalent to 6 lines of an SDRAM when the mapping is carried out on the SDRAM. In this case, however, when each line is divided into 16 words, the final line is divided into 11 words and other remaining words are idle areas since a single line consists of 91 words. Thus, the data on one ECC block are written in the areas of the 1st-78th lines of the SDRAM when an address is designated in a writing mode. When the written data are read out in the PO direction in an ECC process, the data equivalent to 16 words of the processing unit can be read out on the same address. When the written data are read out in the PI direction, the row address has not to be changed because of a fact that the data equivalent to 16 words (11 words of the final line) exist in a single row address.
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