| 摘要 |
PURPOSE:To improve reliability and to reduce costs by detecting the abnormality of a nonvolatile memory in accordance with the check of the storage content in the nonvolatile memory. CONSTITUTION:The storage content in a nonvolatile memory 62 is checked in order to detect the abnormality of the non-volatile memory. The storage content (55H) or (AAH) in the memory 62 is first read out to the A register of a CPU 64. A reference value 55H or AAH for diagnosis determined beforehand in accordance with a diagnosis porgram is then inputted in the D register of the CPU64. The CPU compares the values of the A register and the D register, and decides that the memory is normal when the difference between the same is zero and decides that the memory is abnormal when the difference is except zero. Since the potential sensor for detecting the potential of a backup battery is eliminated by the above-mentioned method, reliability is improved and the costs are reduced. |
