| 摘要 |
An IC card according to the present invention comprises, a built-in coprocessor for an auxiliary arithmetic in addition to a main arithmetic processing unit, an interval timer for outputting an interrupt request signal upon lapse of a set time shorter than the frame waiting time, and coprocessor control means for controlling the coprocessor operation by suspending supply of an operation clock to the coprocessor in accordance with the output of the interrupt request signal and resuming supply of the operation clock to the coprocessor in accordance with a predetermined response input from an external device. Upon receipt of a command from the external device, the contents of the command are determined, and the time shorter than the frame waiting time is set in the interval timer thereby to start the interval timer.
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