Abstract: A semiconductor integrated-circuit card including a microprocessor having an active mode of operation capable of processing data and a low power consumption mode of operation disabled from processing data, the microprocessor being operative to (1) establish the low power consumption mode of operation in the IC card when the microprocessor is initially activated to start operation, (2) make a shift from the low power consumption mode of operation to the active mode of operation responsive to an interrupt signal from an external signal source, and (3) make a shift from the active mode of operation back to the low power consumption mode of operation upon termination of the data processing in the active mode of operation.

Abstract: A semiconductor integrated-circuit card including a microprocessor having an active mode of operation capable of processing data and a low power consumption mode of operation disabled from processing data, the microprocessor being operative to (1) establish the low power consumption mode of operation in the IC card when the microprocessor is initially activated to start operation, (2) make a shift from the low power consumption mode of operation to the active mode of operation responsive to an interrupt signal from an external signal source, and (3) make a shift from the active mode of operation back to the low power consumption mode of operation upon termination of the data processing in the active mode of operation.

Abstract: An information card system according to the present invention establishes a data communication between a terminal unit and an information card after receipt of an acknowledge signal supplied from the information card to the terminal unit, and the acknowledge signal is produced by a combination of a periodical signal retrieving circuit and an output unit incorporated in the information card upon receiving a periodical signal fed from the terminal unit, so that a misfit between the information card and the terminal unit is detectable before the data communication.

Abstract: An integrated circuit card having a one-chip micro computer, a memory, and an address bus and data bus for coupling the micro computer and the memory, includes an input/output bus and interface for communication with an external terminal device. The micro computer executes processing commands from the external device, and returns the processing results to the external device through the interface. Instead of returning the processing results to the micro computer immediately when processing is finished, the IC card includes a timer for measuring elapsed time starting with the receipt of a processing command. The processing results are returned to the external device only when a predetermined elapsed time has been measured by the timer.

Abstract: In an IC (integrated circuit) card, a CPU (central processing unit) is connected to a data bus and an address bus. A data memory is connected to the data bus and the address bus. The data memory is a rewritable memory, such as EEPROM (electrically erasable programmable read only memory) or battery backed-up RAM (random access memory). The data memory is segmented into a predetermined number of sectors each consisting of predetermined bytes. An external processing device, such as a terminal device is connected to the data bus and the address bus, via a one-bit I/O line and a port. The terminal device supplies a processing instruction via the I/O line to the third port. The CPU receives the processing instruction via the data bus, analyzes the instruction, and reads out and executes the necessary program. The CPU supplies the results of each processing to the terminal device, by way of the data bus, the port and the I/O bus.