PURPOSE: To detect the replacement of memory data even if the memory data was replaced at the time to add plural data by adding them in a state in which each data is weighted with the weight of peculiar information corresponding to its stored position.
CONSTITUTION: Addition is executed by using an address counter I 11 for reading sequentially the memory data out of the addresses (n) to n+k of a data area 1, a counter C 12 for generating a peculiar number in order to multiply by the peculiar number different for every stored place of the read-out data, a sum arithmetic register 14 and a sum value arithmetic processing part 13, and the contents of the register 14 is written in a standard added result storage area 2 by a sum value write-in processing part 21. Then, prior to the start of actual sequence arithmetic, processing is executed by the sum arithmetic processing part 13, and the standard added result of a storage area 2 and the contents of the sum arithmetic register 14 are compared by a sum value comparison processing part 22, and sum value coincidence check 23 is executed. Thus, the change of the data stored in the memory and the replacement of the data can be surely checked.
TAKADA TSUTOMU
TAYAMA KATSUYA
OTOMO MASAMI
SANO MASAHARU
HITACHI KEIYO ENG
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