Mattingly, Stanger & Malur, P.C.
Information processing apparatus having a power saving function
 An information processing apparatus such as a personal computer is capable of controlling consumption power of a digital communication line interface circuit or a modem depending on a usage state of the communication line. In one aspect, the information processing apparatus including a digital communication interface circuit connected to a digital line to communicate data, includes a link state detect circuit to ascertain a link state between the interface circuit and the communication line, and a consumption power mode change circuit to change a consumption power mode of the interface circuit depending on the link state ascertained by the detect circuit. In another aspect, a battery-driven hand-held information processing apparatus minimizing the consumption power includes an access detection circuit to monitor an access state of software to a serial interface circuit, a timer circuit to determine that a modem is not accessed for a fixed period of time, a power control circuit to turn power of a modem circuit on and off in accordance with a result from the timer circuit, a circuit to generate a signal which masks a transmission enable signal notifying the serial interface circuit that the modem is unavailable because power of the modem circuit is off, and a mask circuit operating in response to the mask signal. 
Hitachi, Ltd.
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additional additional inventional inventional
Yoshiaki Yosuke Shigeharu Nobuhiro
Nomura Konaka Koyanagi Kato