What is ACPI

What is ACPI, OnNow, and PCI Power Management?

Microsoft began an initiative called OnNow to shorten the PC's "power-up" time in order to allow the PC to begin interacting with a user's environment. Basically, if a user turns a PC off, then that PC cannot monitor the thermostat, answer the telephone, turn lights on and off, etc. Microsoft then began defining a PC which was "green" friendly and could wake up from a "sleep" state very quickly.

As Microsoft moved the concept of OnNow into a specification they defined the ACPI (Advanced Configuration Power Interface) specification. The ACPI specification deals with the concepts of OnNow on a high level, but begins to define device level requirements by defining new specifications which must be adhered to in future designs.

For the TI PC Card Controller family, the relevant device specification was the PCI Bus Power Management specification, which defines the ACPI requirements for devices which have a PCI bus interface. In the future, PC Card Controllers will also need to be compliant to the CardBus Device Class specification.

来自: https://www.ti.com/sc/docs/products/msp/intrface/pci/tech.htm