The ACPI standard [1] was developed by Intel, Toshiba, and Microsoft and has been adopted by most PC manufacturers. Figure 1 shows the main components of a system that uses ACPI. At the lower level, the ACPI standard defines a set of tables that describe the hardware platform, a BIOS API for low-level management operations, and a pre-defined set of registers. In the upper level, the operating system contains some core software and drivers used to communicate with APCI in addition to the usual device framework and drivers used to manage non-ACPI devices. In this section we examine both levels of the ACPI architecture.
