| 摘要 |
PURPOSE:To continue normal operation changing a normal memory to common use so for abnormality is not of the same address by not making cutting off from a system of common use side when the abnormality is detected in common use side, but by switching the common use/standby that switches standby side to the common use side and vice versa. CONSTITUTION:An address decode section 24 outputs a device select signal 18(SEL) to make the reading or writing of data of a memory 11 only when the memory 11 is accessed from a master device through a system bus 9. When there is abnormality in write data and read data to the memory 1, an error detecting section 2 outputs an error detection signal 3 (ERR) to a duplication control section 14. When the flip flop of the memory 11 is reset, a signal 21' (ACK) disappears in the memory 11' of the standby side, flip flop 15' is set to become the common use side. By setting of the flip flop 15' of the memory 11' which has been in the standby side, the signal 21(ACK) of the memory 11 which so far been in the common use side becomes effective. |
