| 摘要 |
PURPOSE:To prevent the noise of the cooling fan motor and a waste of electric power when the external storage device is not used, by supplying power to the external storage device only when the processor uses the external storage device. CONSTITUTION:When power source 19 of processor 1 is made, power supply detecting circuit 5 detects DC voltage signal 7 to generate detection signal 23 on signal line 9. Processor 1 receives this detection signal to transmit the relay driving signal to relay controlling circuit 3 through signal line 13, and relay switch 4 is turned on to supply power to external storage device 2. If a medium is inserted into external storage device 2, control siganl 25 rises on control signal line 12, and processor 1 detects this signal to execute data transfer. If the medium is not inserted into external storage device 2, control signal 25 does not rise, and therefore, processor 1 sets external storage device 2 to the power supply state and is held for a prescribed time until device 2 becomes available. |
