| 摘要 |
PURPOSE:To hold the contents in a state before an electric power source is turned off, in a storage device, by providing a storage device control part which stores whether the turn-on is initial turn-on or re-turn-on when an AC power supply has been turned on, and is operated by a signal for setting whether initial write can be executed or not. CONSTITUTION:Initial electric power supply turn-on to a storage device 3 and a CPU2 from an electric power source device 1 is discriminated by an initial write IW execution propriety conrolling circuit 15 of the storage device 3, a gate 16 is turned on, and when a data is written to the device 3 from the CPU2, a system clear signal 10 is released. In case when DC supply to the CPU2 and the device 3 from the device 1 has been stopped, contents of the device 3 are held by DC supply from a battery backup device 6, and whether turn-on of the CPU electric power supply is initial or not is stored in a circuit 15. When the electric power supply of the device 1 is returned, a control signal 9 of IW is sent to the device 3 from the CPU2 until the signal 10 is released. Therefore, the circuit 15 discriminates that the electric power supply has been returned after a fault, the gate 16 is closed, IW to the device 3 is not executed, and as for stored contents, the contents before the device 1 is turned off are held. |
