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Open Firmware

The ROM-in-RAM software architecture follows some of the standards defined by the Open Firmware IEEE 1274-1994 specification and the CHRP binding.

The primary Open Firmware reference is the IEEE 1275-1994 Standard for Boot (Initialization, Configuration) Firmware: Core Requirements and Practices. You can order that document electronically from the IEEE Standards Department website at

http://standards.ieee.org/catalog/bus.html

or you can order it by mail from

IEEE Standards Department
445 Hoes Lane, P. O. Box 1331
Piscataway, NJ 08855-1331
Telephone 800-678-4333 (US), 908-562-5432 (International)

The basis for the bootinfo file format and use is described in the document PowerPC Microprocessor Common Hardware Reference Platform (CHRP) System Binding to: IEEE Std 1275-1994 Standard for Boot (Initialization, Configuration) Firmware. A bootinfo file contains Open Firmware script, a description, information for individual operating systems, icons, along with other information.

An introduction to Open Firmware as used with PCI expansion cards on the Macintosh computer is given in Designing PCI Cards and Drivers for Power Macintosh Computers.

Three technotes provide additional information about Open Firmware on the Macintosh computer. They are

• TN 1061: Open Firmware, Part I, which introduces Forth programming, describes a typical device tree, and outlines a technique for debugging Open Firmware drivers. It is available on the Technote website at http://developer.apple.com/technotes/tn/tn1061.html
• TN 1062: Open Firmware, Part II, which describes the contents of an expansion ROM for Open Firmware and lists properties common to all device types. It is available on the Technote website at http://developer.apple.com/technotes/tn/tn1062.html
• TN 1044: Open Firmware, Part III, which describes a typical device tree. It is available on the Technote website at: http://developer.apple.com/technotes/tn/tn1044.html

Additional information about Open Firmware is provided at Apple's developer Q&A site

http://developer.apple.com/qa/hw/hw-1.html