The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 21, 1989
Filed:
Mar. 30, 1988
Seietsu Nara, Yokohama, JP;
Tomoko Yamauchi, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
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.