| 摘要 |
<p>CARD CALLING TELEPHONE SYSTEM A card calling telephone system in which information is transformed bidirectionally between the card and the telephone by way of optical pulses. To this end, the card includes a photovoltaic cell to be illuminated by the telephone for powering the card's electronics, a photodiode for receiving optical signal pulses from the telephone, a display for generating optical signal pulses for transferring information to the telephone, and control circuits including an E2PROM and a microprocessor. Information which can be stored in the E2PROM under control of the telephone includes a list of numbers frequently called and the amount of prepaid credit remaining on the card.</p> |
