| 摘要 |
PURPOSE:To remove a data reading defect area generated by the abnormality of management information. CONSTITUTION:Management information for managing an EEPROM 40 forming a data area is stored in a byte rewritable type or bit rewritable type EEPROM 30. At the time of rewriting the management information, a recording starting flag indicating the start of recording is recorded at first, the initial management information, e.g. header information indicating the approximate using state of a data area, is written following the flag, and then packet identification(ID) information e.g. in each data are recorded. As the ID information, a value indicating an error is written in an abnormal detecting bit and then MAT information indicating the arrangement relation or the like of packets is recorded. Then, data are recorded in the EEPROM 40, and after ending the recording, the abnormal detecting bit is returned to '0' and the recording starting flag is reset. Consequently, which management information is abnormal, can be checked by checking the states of the recording starting flag, the abnormal detecting flag and the ID code. |
