| 摘要 |
PURPOSE:To make a special hardware for decision needless by deciding availability of power failure security on a basis of comparison and collation with a fixed pattern of a ROM in a volatile semiconductor memory which is secured against power failure by a battery. CONSTITUTION:When power is supplied to a CPU, a comparison and collation fixed pattern of fixed pattern area 1 of a ROM is transferred to compared and collated area 3 of a RAM previously. Next, when supply power is turned off, the RAM is secured against power failure by a battery; and when power is restored after that, contents of area 1 of the ROM and contents of srea 3 of the RAM are compared and collated with each other by the CPU. If contents of all words agree with each other respectively as the result of collation, it is decided that data area 4 of the RAM is not broken down. In case of disagreement of any one word in collated contents, it is decided that area 4 is broken down, and the first operation is executed. Then, the operations above are repeated in order. |
