Data processing apparatus using reader/writer and data carrier

Abstract

A response permission command is transmitted from a reader/writer, thereby setting all of data carriers to a response possible state. Subsequently, a data return command is transmitted, thereby returning data for collation on a bit unit basis. The reader/writer transmits a data collation command of, for example, bit 0 to each of the data carriers when recognizing the return of the data in which bits 0 and 1 mixedly exist. When an own return bit coincides with a collation bit, each of the data carrier judges that the collation succeeds and returns a next bit for collation. When they don't coincide, however, a state of the data carrier is switched to a response inhibition state. By repeating such processes with respect to all of the bits of the data for collation, only one data carrier finally remains in a response possible state and generates an access permission command, thereby performing the reading or writing operation. When the operation is finished, the state is switched to an access inhibition state by an access inhibition command. The processes from the transmission of the response permission command are again repeated for the remaining data carriers.

Dependencies are inferred from the claim text.