Portable information processor having password code checking function

摘要

While ensuring adequate security, switching between requiring mode and non requiring mode of the checking of a password code for use is enabled. An EEPROM (11) and an IC card with a CPU for accessing this EEPROM are prepared. The general data in the EEPROM are stored upon attachment of error check codes. The memory area of EEPROM (11) is partitioned into unit areas of 2-byte length and writing is performed according to unit area. The MSB of a specific unit area Ux is used as a checking requirement flag with "1" being defined as checking "required" and "0" being defined as checking "not required". A password code checking process is carried out only in the checking "required" mode. An error check code is not added to the data in the unit area Ux. In rewriting the checking requirement flag, an erasure process of setting all bits in the unit area Ux to "1" is performed and thereafter the desired flag is set in the MSB.