Patent ID: 7995643

Claim:
A unit to be removably attached to an electronic apparatus, the electronic apparatus having a generating part which generates a fixed-length packet by dividing data to be transmitted into fixed-length sub-data and by appending a termination identifier, which is for representing a termination point of the sub-data, to the sub-data, the unit comprising: a receiving part which receives the packet from said electronic apparatus; a detecting part which executes a first data error detection based upon the termination identifier included in the received packet; a data converting part which, if data error has not been detected by said detecting part, converts sub-data, which has been extracted from the received packet, to sub-data for authenticating said unit; and a transmitting part which transmits sub-data for authenticating said unit to said electronic apparatus if data error has not been detected, and sends said electronic apparatus data for notifying of the fact that an error has occurred if data error has been detected.