| 摘要 |
PURPOSE:To prevent the malfunction of a device such as a measuring instrument, by writing prescribed data for power failure detection in a prescribed area of a semiconductor memory to be backed-up and reading out this data by a CPU to detect the power failure when power is turned on. CONSTITUTION:If the user of the device turns off a switch SW2 when he turns off a power source 4, an interlocking switch SW1 is turned off. In this case, contents of a RAM are changed because a back-up power source 1 cannot back up the RAM. Meanwhile, if power is not supplied from a power source AC under the state, where the switch SW2 is turned on, because of power failure, the power of the power source 1 is supplied to the RAM. When the power of the device is restored, contents of the RAM are checked to discriminate whether contents of the RAM are changed or not. |
