Portable medium
First Claim
1. A portable medium having a control element which controls a data memory, comprising:
- input means for inputting various instructions for causing said control element to perform various operations;
first clock means for generating a clock signal of a first frequency;
second clock means for generating a clock signal of a second frequency which is higher than that of the first frequency; and
clock control means for causing said second clock means to start generating the clock signal, in response to an instruction supplied from said input means, for supplying the clock signal of the first frequency generated by said first clock means to said control element, and, when the next instruction is supplied from said input means, for supplying the clock signal of the second frequency generated by said second clock means to said control element.
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Accused Products
Abstract
An IC card, i.e., a portable medium, contains a data memory and a CPU functioning as a control element. The IC card has a keyboard and a built-in battery. It also includes a clock controller, a first clock generator always generating a low-frequency clock signal, and a second clock generator having a oscillator, for generating a high-frequency clock signal. When the IC card is used in an off-line mode, that is, when it is used by itself, it is driven by the battery. The CPU performs various operations in accordance with the signals input by operating the keyboard. When the power-on key of the keyboard is pushed in the off-line mode, the clock controller supplies the low-frequency clock signal to the CPU, and simultaneously causes the second clock generator to generate the high-frequency clock signal. When the next signal is input from the keyboard, the clock controller supplies the high-frequency clock signal, instead of the low-frequency clock signal, to the CPU.
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Citations
21 Claims
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1. A portable medium having a control element which controls a data memory, comprising:
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input means for inputting various instructions for causing said control element to perform various operations; first clock means for generating a clock signal of a first frequency; second clock means for generating a clock signal of a second frequency which is higher than that of the first frequency; and clock control means for causing said second clock means to start generating the clock signal, in response to an instruction supplied from said input means, for supplying the clock signal of the first frequency generated by said first clock means to said control element, and, when the next instruction is supplied from said input means, for supplying the clock signal of the second frequency generated by said second clock means to said control element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A portable medium having a control element which controls a data memory, comprising:
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first clock means for always generating a clock signal of a first frequency; second clock means for generating a clock signal of a second frequency which is higher than that of the first frequency; clock control means for switching a clock signal which drives said control element, from the clock signal of the first frequency generated by said first clock means to the clock signal of the second frequency generated by said second clock means to said control element; detecting means for determining that the clock signal of the second frequency is correctly generated by said second clock means, before said clock control means switches the clock signal; and means for causing said clock control means to switch the clock signal when said detecting means determines that the clock signal of the second frequency is correctly generated by said second clock means. - View Dependent Claims (20)
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21. A portable medium having a control element which controls a data memory, comprising:
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input means for inputting various instructions for causing said control element to perform various operations; first clock means for generating a clock signal of a first frequency; second clock means for generating a clock signal of a second frequency which is higher than that of the first frequency; and clock control means for causing said second clock means to start generating the clock signal, in response to an instruction supplied from said input means and for supplying the clock signal of the second frequency generated by said second clock means to said control element.
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Specification