| 摘要 |
PURPOSE:To lighten the burden of a CPU for checking the content of a memory at the time of restoration of power supply, by successively reading out the content of the memory by means of an address generator for scanning and checking the whole contents by the memory device itself by means of an error detecting circuit. CONSTITUTION:Data communication before a power failure is performed in such a way that a selector 10 outputs an external address 8 given through a connecting bus 2 as the address of a memory 7 and, when a power failure occurs, a back-up power source holds the content of the memory 7. When the power supply is restored, a power supply restoration controller 12 outputs a restoring signal 14 so as to drive an address generator 9 for scanning and, at the same time, switches the selector 10 to the generator 9 side so as to read out all contents of the memory 7. An error detecting circuit 11 checks the successively read out data and outputs the checked results to the controller 12. The controller 12 switches the selector 10 to the external address 8 after checking all the contents of the memory 7 and, at the same time, holds the error detected results as memory error information and outputs a memory error information signal 15. |
