| 摘要 |
PURPOSE:To improve the reliability of an integrated circuit card by securing an area to store the back-up data against the data on a directory area in a built-in E<2>PROM or a parity bit for parity check. CONSTITUTION:Two directory areas 31 and 32 are secured in a memory and the remaining part of the memory is used as a memory area 33. The data are written into the area 33 when an ID card is used with those data erased on both areas 31 and 32. Then the written data on the final address is written into both areas 31 and 32 respectively. The data are read out of both areas 31 and 32 for reference before data are written into the area 33. In this case, the data on both areas 31 and 32 are always compared with each other. When the same contents are obtained between both data, it is decided that the data on both areas 31 and 32 are not broken and show the correct information. |
