A transaction card having in it a semiconductor microcomputer with data storing capability is inserted into a receptor having circuitry for interacting with the microcomputer. Operating power and a clock signal for the microcomputer are transferred from the receptor to the card via an inductive coupling between a coil and magnetic core in the receptor and a coil and ferromagnetic member constituting a flexible wafer inductive device ("FWID") in the card. For purposes of data transfer between the card and receptor, the card includes two additional FWIDS which, when the card is in the receptor, are inductively coupled with corresponding coils in the receptor. One of such additional FWIDS is used to transfer data from the microcomputer in the card to a microcomputer in the receptor, while the other additional FWID is used for data transfer in the opposite direction between these two microcomputers. That data transfer is accomplished by modulating the data signal on the clock, inductively transmitting the modulated signal across the discontinuity between the card and the receptor, and then demodulating the modulated signal to recover a replica of the original data signal.