ACPI : Computer Hardware Buyers’ Glossary



ACPI (Advanced Configuration and Power Interface). A specification for BIOS (Basic Input Output System) features to allow a desktop computer go into various power-saving modes of sleep.

working state
Normally a computer is in working mode when it is fully powered up and executing instructions.
sleeping state
If a computer shuts down to conserve power, but keeps RAM powered up read for rapid restart, that is called sleeping.
hibernation state
In hibernation, the state of the comuter is saved to disk and RAM is powered off to conserver power. It takes longer to recover, but it is safe from power failure.
soft-off state
Soft-off means the computer is powered off, with just a few components left running so that a keystroke can restart the computer ready for reboot. USB ports, Ethernet cards, the mouse, clock (alarm) can bring a computer out of one of soft-off, hibernation or sleep state.
mechanical-off state
Mechanical off is equivalent to pulling the plug. Only the real time clock continues to run. To bring it out of this state, you would need a UPS (Uninterruptible Power Supply) with AC (Alternating Current) power control.

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