Advanced Power Management (APM)
Definition - What does Advanced Power Management (APM) mean?
The first version was released in 1992 and the latest APM specification was Revision 1.2 released in 2006. Microsoft discontinued support for APM starting with Windows Vista in favor of the advanced configuration and power interface (ACPI).
Techopedia explains Advanced Power Management (APM)
Communication is bi-directional, meaning that power management events are relayed from the BIOS to the OS APM driver, and the APM driver can send requests to the BIOS through function calls.
The APM driver simply acts as an intermediary between the OS and BIOS. Power management can occur through power state change requests or automatically through set parameters based on device activity.