| 摘要 |
<p>PURPOSE:To secure the interchangeability between a standard IC card and a terminal array and to prevent the consumption of a built-in battery with no increase in the number of terminals of the card by detecting the stop of supply of a high speed clock via a card itself and switching clocks. CONSTITUTION:An external clock detection means 4 detects a 1st clock S1 supplied from outside, and a clock switch means 5 switches the clock S5 supplied to a processor 6 in accordance with the output S4 of the means 4. In other words, the clock S5 supplied to the processor 6 from the means 5 is switched to the clock S1 when the means 4 detects the clock S1 supplied from outside. Otherwise the clock S5 in switched to a 2nd clock S2 which is produced by an internal clock generating means 3 provided to a one-chip microprocessor. In such constitution, the switch is attained between the high and low speed clocks in simple constitution without increasing the number of external terminals. Thus the consumption of a built-in battery can be extremely prevented.</p> |
