Multi-mode power switching for computer systems

  • US 5,758,175 A
  • Filed: 12/17/1996
  • Issued: 05/26/1998
  • Est. Priority Date: 06/01/1990
  • Status: Expired due to Term
First Claim
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1. A computer system comprising a power management system and a plurality of computer system circuits including a CPU circuit, a plurality of input/output circuits, a memory circuit, and a system bus which directly connects the CPU circuit with the input/output circuits, said computer system adapted to perform a plurality of activities, wherein said power management system comprises:

  • an activity monitor which monitors the activity of the computer system including;

    means for identifying each of said plurality of activities as either an active activity or an idle activity and for associating each of said plurality of activities with a predetermined activity value and with either a first arithmetic sign for activities identified as active activities or with a second arithmetic to said first sign for activities identified as idle activities;

    an activity count accumulator for accumulating an activity count upon the occurrence of each of said plurality of activities including;

    means for adding to a stored activity count, upon the occurrence of any one of said plurality of activities, a predetermined activity value associated with said particular activity; and

    means for comparing the accumulated stored activity count with a conserve threshold and for causing a CONSERVE signal if the accumulated activity count has a predetermined algebraic relationship relative to the conserve threshold; and

    a mode controller responsive to the activity monitor wherein the mode controller has a plurality of power modes of operation including a first mode and a second mode; and

    a power control circuit coupled to said activity monitor which in response to the CONSERVE signal transitions from an ON state to a REDUCED state in which the power consumption of the computer is reduced relative to the power consumption in the ON state.

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