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Open Firmware

The Open Firmware component of NewWorld is based on the CHRP version of Open Firmware, also known as Open Firmware 3.0. This is the most robust and full-featured Open Firmware used by Apple to date. This version of Open Firmware contains several notable changes from the Open Firmware found in the first and second generation PCI Macintosh computers:

• Open Firmware is capable of reliably reading files from block devices.
• Open Firmware builds an expanded device tree that holds every facet of hardware information needed by an operating system.
• Open Firmware contains code that mimics the StartSearch code in the Mac OS ROM and provides a Mac-like user interface during startup.
• Open Firmware creates an interrupt tree that is interlaced through the device tree to provide a mechanism to describe the interrupt layout of the computer.

If a boot failure occurs in Open Firmware, Open Firmware attempts to provide a Macintosh-like experience.