An RFID interface integrated-circuit chip has three ports including a bi-directional RF port, a serial or parallel data external memory IC port, and a serial or parallel data external electronic system port. DC power is supplied to a separate external memory IC chip through the serial external memory port either from power obtained from an RF signal through the bi-directional RF port, from DC power provided from an external electronic system, or from an auxiliary voltage source, such as a battery or fuel cell that replaces power provided from the RF signal. Data and control signals are interchanged with the separate external memory IC chip through the serial or parallel external-memory port using the RF port when the external electronic system is not available or through the external electronic system serial or parallel port when the external electronic system is available.