| 摘要 |
PURPOSE:To prevent the mutual interference of memory areas without increasing the load to an OS nor reduction of the executing speed, by permitting an access with reference to a table against the combination of the types between accesses and memory areas. CONSTITUTION:A logical address outputted from a processor 1 includes an access bit showing the classification of a relevant access. The high-order bits of the logical address show the page numbers with the low-order bits showing the intra-page addresses respectively. On the other hand, a page map 4 stores the protection bits to the page numbers and the page numbers are given to the map 4 from a memory control unit MMU2. Then the corresponding protection bit is extracted. This protection bit and the access bit are set opposite to each other on a table of a comparison means 5 for decision of access permission or inhibition. As a result, the mutual interference is avoided among divided memory areas without deteriorating the fast executing speed.
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