| 摘要 |
A memory card is provided having a memory, in which data entered through a plurality of data input-output terminals are written. The voltage of a backup battery for supplying the memory to preserve the data therein is compared with two different reference voltages so as to detect two binary battery check signals. When the memory card is loaded in an electronic device, one of the two battery check signals is outputted to the electronic device through one of the data input-output terminals, while the other battery check signal is outputted through a battery check terminal. Alternatively, both of the battery check signals are outputted through two of the data input-output terminals. The electronic device displays a condition of the backup battery by energizing green, yellow or red LEDs to emit light, in accordance with the battery check signals.
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