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Open Firmware

Macintosh computers that use an Intel microprocessor do not use Open Firmware. Although many parts of the I/O registry are present and work as expected, information that is provided by Open Firmware on a PowerPC Macintosh (such as a complete device tree) is not available in the I/O registry on a Macintosh that uses an Intel microprocessor. You can obtain some of the information from IODeviceTree by using the sysctlbyname or sysctl commands.

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