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
- 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.