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Leopard Technical Q&As: Hardware & Drivers
Open Firmware is the nonproprietary name of firmware that complies with IEEE Std 1275-1994. It is the ROM-based software that tests and initializes the hardware, determines the hardware configuration, loads or boots the operating system, and provides interactive debugging facilities in case of faulty hardware or software.

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IODeviceTree and the I/O Registry (HTML) (日本語 HTML)
QA1120: Describes the IODeviceTree plane in the Mac OS X I/O Registry.
Disabling Processor Cores on a Multi-Core System (HTML) (日本語 HTML)
QA1141: Describes how to disable processor cores on a multi-core system for testing purposes.
DDR SDRAM ICs for PowerBooks and iBooks that use Memory bus slewing (HTML)
QA1344: Specifies DDR SDRAM IC optimization for PowerBooks and iBooks that use Memory bus slewing.
Determining Open Firmware version (HTML)
HW100: Demonstrates how to find out the version of Open Firmware on your Macintosh.
Was that a path I just saw? (HTML)
HW101: Describes the Open Firmware path that is occasionally shown at boot time.
What is an Open Firmware devalias? (HTML)
HW99: Describes devaliases in Open Firmware.
The "/aliases" node in the device tree (HTML)
HW89: Describes the aliases node in the Open Firmware device tree.
Locating the 1275-1994 Standard Document (HTML)
HW85: Alerts that the Open Firmware (IEEE 1275-1994) document can't be found at the IEEE Standards Association site.
What is an Open Firmware phandle, and why can't I access it from the Mac OS? (HTML)
HW76: Explains an "Open Firmware phandle" and why it is inaccessible from the Mac OS.
Are the Name Registry device tree nodes unique? (HTML)
Deprecated - HW64: Discusses whether Name Registry nodes copied from the Open Firmware device tree are unique.
Can you explain the words "begin" and "again"? (HTML)
HW70: Explains the Forth looping words "begin" and "again" and how to escape such a loop.
Using "words" in Open Firmware (HTML)
HW73: Explains how to search for specific entries within all the global and local Open Firmware words.
What is the return stack in Open Firmware and can I use it? (HTML)
HW67: Describes the purpose of the Open Firmware return stack and how developers can use it.
The AAPL, slot-name property and PCI (HTML) (日本語 HTML)
HW61: Discusses the use of the AAPL,slot name property for PCI
What is a tokenizer? (HTML) (日本語 HTML)
HW58: Defines a tokenizer.
Changing the configuration variable in Open Firmware (HTML) (日本語 HTML)
HW40: Tells how to change the configuration variable in Open Firmware.
Difference between an Open Firmware word and method (HTML) (日本語 HTML)
HW46: Describes the differences between an Open Firmware word and an Open Firmware method.
Switching between one and two machine mode for the Open Firmware user interface (HTML) (日本語 HTML)
HW37: Explains how to change from one machine mode to two in the Open Firmware user interface.
What are generic names in Open Firmware? (HTML) (日本語 HTML)
HW34: Documents the generic names in Open Firmware.