Open Firmware was originally developed by Sun Microsystems and is now standardized as IEEE 1275-1994 [6]. It is currently used in the SPARC architecture, the PowerPC architecture, and the ARM architecture. Open Firmware acts as monitor that can interpret the Forth language. It covers the boot process, device configuration, and power management. Operation systems running on Open Firmware based machines must implement some architecture-dependent way to access the firmware interpreter for use in auto-configuration.
ACPI and Open Firmware are similar in that some functions of the firmware are written for an interpretor. This makes it easier to extend without breaking compatibility. But the most important difference is that ACPI byte code is interpreted by the operating system, while Open Firmware Forth code is interpreted by the firmware itself. The Open Firmware solution provides a powerful framework to describe and extend functionally, but this is not accepted in Intel architecture (IA32/IA64) for the following reasons: