| 摘要 |
PURPOSE:To attain the continuous use of the preservation data by using a nonvolatile ROM which preserves the data on the device controlled by a ROM substrate. CONSTITUTION:A nonvolatile RAM11 makes use of an external power supply circuit 12 or a battery 10 to preserve the data on the device to be controlled in a nonvolatile way. This RAM11 is set on a ROM substrate 3 which is separate from a main substrate 5 containing peripheral circuits of a CPU4. In case the substrate 5 is totally exchanged owing to a fault of the CPU4 or its peripheral circuit, for example, the preservation data can be used continuously with no erasion since the RAM11 is provided to the substrate 3. |
