| 摘要 |
PURPOSE:To easily cope with a temporary voltage drop, by providing a means for checking an error of a data read out from a storage device, when switching the storage device to a back-up battery at the time of disconnection of an electric power supply, and detecting a voltage drop of the battery. CONSTITUTION:When a back-up battery 2 is turned on at the time of disconection of an electric power supply, a controlling circuit 5 operates, a storage device supplies an address signal, a storage address is driven in order, and a stored data is read out in order. In case when stored contents have been broken down due to an operating voltage drop, a parity checking circuit 11 automatically checks whether it is a pairty error or not, at the time of read-out operation. When an error is detected by the parity checking circuit, an alarm is raised from the controlling circuit 5, the operation is discontinued, and the stored contents are corrected. In this way, a voltage drop is detected easily. |
