| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately judge whether data stored in a rewritable external storage device are correct or not. <P>SOLUTION: A memory 6 is provided with three areas 1 to 3, and each area is provided with a data storage area 6a for storing the same data and a check sum storage area 6b for storing check sum calculated for each area. A CPU 3 is provided with a standard check sum storage area 3a for inputting each majority check sum, a control constant storage area 3b for inputting each majority data, a control constant check sum storage area 3c for inputting the check sum of the control constant storage area and a comparing part 3d for comparing the reference check sum with the control constant check sum. When the both check sums are matched, it is judged that the control constant is correct. The data are checked doubly by different methods, and when it is decided that the area of the majority data or the reference check sum is correct, it is possible to surely prevent the erroneous decision of data. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
