Erroneous-operation preventive apparatus

摘要

An erroneous-operation preventive apparatus operable with an operation medium has a unit for receiving the operation medium. The unit includes first and second data modifiers and the operation medium stores first data, second data equal to the first data modified by the first data modifier, and third data equal to the first data modified by the second data modifier. When the operation medium is set in the unit, the first and second modifiers modify the first data from the operation medium. The modified first data is compared with the second and third data from the operation medium to decide the correctness of operation when the comparison results indicate a predetermined relationship between the modified first data with the respective second and third data.