A firmware component is essential for embedded systems using Intel architecture designs. The firmware layer plays a critical role in embedded system power management. OS-directed power management using the Advanced Configuration and Power Interface (ACPI) methodology is a solution that allows for cost-effective firmware development and quick time to market. Pushing state machine management and decision policies to the OS and driver layer allows post-production flexibility for tuning power management. This article explores how ACPI has provided efficiencies over APM and BIOS-directed power management and provides a condensed overview of APCI technology.