the value of the PWRGOOD signal (32) is sampled (step 42). In the case that the value is «0» (indicating that the system is in shutdown state), no operation is required and the system reverts to idle state (44), awaiting an event. If, on the other hand, the value in step (42) is «1», indicating that the poweris on, then a PWRBTN# signal («0») is triggered (43) and fed to the ACPI module ((26) in FIG. 2). The latter, depending upon its operational state, will trigger an ONCTL# signal de-asserted. In the common case when the system is functional this will bedone via a call to the CPU (21) that will handle the shutdown process and will give the proper turn-off command. When the system is not functional this will be done by the ACPI state machine directly after 4-seconds.
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