| 摘要 |
PURPOSE:To decide whether a backup is normal or not, by storing the contents of plural expected addresses in a volatile memory by a backup power source when a main power source is turned off, and reading the contents of the volatile memory when the main power source recovers. CONSTITUTION:When the main power source 4 is turned off, a necessary backup circuit 3 is powered up by the auxiliary power source 6 and the sum of the contents of addresses a0-an-1 of the volatile memory 2 is stored in its address an. When the main power source 4 recovers, a backup discriminating circuit 5 calculates the sum of the contents of addresses a0-an-1 of the memory 2 and then compares the sum with the contents of the address an. When they coincide with each other, it is decided that the necessary backup circuit 3 is powered up normally. Consequently, a decision on whether a backup is normal or not is made easily. |
