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Technical Q&As: Hardware
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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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.
2004-03-18
Disabling a Processor on a Multiprocessor System (HTML) ()
QA1141: Describes how to disable a processor on a multiprocessor system for testing purposes.
2002-05-22
IODeviceTree & the IORegistry (HTML) ()
QA1120: Describes the IODeviceTree plane in the Mac OS X IORegistry.
2002-02-13
FCode & OS X (HTML) ()
QA1106: Provides useful tips for Open Firmware debugging on on machines introduced in 2001 or later.
2002-01-15
Determining Open Firmware version (HTML)
HW100: Demonstrates how to find out the version of Open Firmware on your Macintosh.
2000-10-06
Was that a path I just saw? (HTML)
HW101: Describes the Open Firmware path that is occasionally shown at boot time.
2000-10-06
What is an Open Firmware devalias? (HTML)
HW99: Describes devaliases in Open Firmware.
2000-10-06
Why didn't I boot from the CD? (HTML)
HW98: Describes the behavior of holding down the "c" key at boot time.
2000-10-06
The "/aliases" node in the device tree (HTML)
HW89: Describes the aliases node in the Open Firmware device tree.
2000-09-05
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.
2000-07-17
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.
1999-11-15
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.
1999-10-11
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.
1999-10-11
Using "words" in Open Firmware (HTML)
HW73: Explains how to search for specific entries within all the global and local Open Firmware words.
1999-10-11
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.
1999-10-11
The AAPL, slot-name property and PCI (HTML) ()
HW61: Discusses the use of the AAPL,slot name property for PCI
1999-04-19
Converting a numeric string to a number under Forth (HTML) ()
HW52: Demonstrates numeric string conversion in Forth.
1999-03-29
What is a tokenizer? (HTML) ()
HW58: Defines a tokenizer.
1999-03-29
Changing the configuration variable in Open Firmware (HTML) ()
HW40: Tells how to change the configuration variable in Open Firmware.
1999-02-15
Difference between an Open Firmware word and method (HTML) ()
HW46: Describes the differences between an Open Firmware word and an Open Firmware method.
1999-02-15
Switching between one and two machine mode for the Open Firmware user interface (HTML) ()
HW37: Explains how to change from one machine mode to two in the Open Firmware user interface.
1999-02-15
What are generic names in Open Firmware? (HTML) ()
HW34: Documents the generic names in Open Firmware.
1999-02-15
ANSI SCSI Standards (HTML)
Deprecated - DV03: Describes past Macintosh systems that did not fully support the ANSI SCSI-1 standard.
1995-07-01