| 摘要 |
PURPOSE:To obtain a memory protective device where fine division, change of protective information, and high-speed operations are possible, by reading and writing information efficiently from and on a memory for control where memory protective information is stored. CONSTITUTION:A upper high-order part 3 of a low order address 4 of the address given from the external is inputted to a comparator 16 and is compared with contents of a register 15 where the same part of the preceding input address is held. At this time, if a write signal 10 is effective to indicate write to the memory and the comparator 16 outputs a coincidence signal, contents of the register 15 are used as an address to output memory protective information from a memory 17 for control to a starting device 7. Meanwhile, if the comparator 16 outputs a dissidence signal, contents of the register 15 are changed to a current given value, and the memory 17 for control is read by the updated address to output memory protective information to the starting device 7. The starting devide 7 discriminates operation contents to a memory 8, and the low-order address 4 of the external address is used as an execution address of the memory 8 at an execution time. Thus, the write operation is performed at a high speed, and fine division of protection designation and change of protective information are facilitated. |
