| 摘要 |
PURPOSE:To perform accurate judgment of battery backup of volatile memory without using special hardware by consecutively reading the content of a volatile memory, and executing validity check such as parity check. CONSTITUTION:When the main power source 1 is turned on, a direct current is fed to the central processing unit 3 from the power source controlling unit 2 and the central processing unit 3 generates a power-on reset signal. Using this signal as a trigger, the execution starts in the central processing unit 3 from the fixed address of a ROM 4, initializing the central processing unit 3. The reading is performed without writing for the entire area of a RAM 5 supported by the battery backup or validity check. If all address is normal backup is assured and if parity error occurs in any of the address, backup is judged as not assured. |
