Open Firmware

Open Firmware, now also known as OpenBIOS, is hardware-independent firmware (computer software which loads the operating system) initially developed by Sun Microsystems for use in their -based workstations and servers. It was described in 1275 and adopted by PowerPC-based systems such as . However, IEEE 1275-1994 was not affirmed by the Open Firmware Working Group in 1998 and has since been withdrawn.IEEE Standard for Boot (Initialization Configuration) Firmware: Core Requirements and Practices, Institute of Electrical and Electronics Engineers. 1994.That same Open Firmware Forth system by DonHopkins, Y Hacker News. 2015-07-07.
Open Firmware may be accessed through its , which is based on the .
==Apple and Open Firmware==
Apple Computer adopted Open Firmware with its PCI-based Power Macintosh models, starting with the Power Macintosh 9500 in 1995. For such models through the beige Power Macintosh G3, the classic Macintosh Toolbox was stored within the boot ROM itself as an Open Firmware device. Thus, they are still classified as Old World ROM systems. Starting with the first iMac G3 in 1998, a bootloader would instead load New World ROMs from the boot drive. The Open Firmware interface can be accessed at startup by holding down the   COMMAND + OPTION + O + F   keys.A guide to Open Firmware - The Apple BIOS by linuxopjemac, iLinux. 2010-02-06. Archived 2010-05-23.NetBSD/macppc Model Support, NetBSD. Accessed 2021-03-04.
===Booting===
Open Firmware on PowerPC Macs can boot from a drive volume partitioned through an Apple Partition Map (APM). However, it is unable to support booting from drives partitioned through a GUID Partition Table (GPT) favored by Intel-based Macs, though such volumes can be mounted and accessed.Open Firmware Macs cannot boot from GPT partitioned disks by komakino, Ars Technica OpenForum. 2005-03-31.
===Version history===
Open Firmware versions are not indicative of release order as Apple tended to release newer firnware in portable PowerPC notebooks than desktop models.The Open Firmware Wiki by z970, MacRumors. 2020-02-28. Some firmware updates were released with a confusing naming convention where it was unclear whether the number referred to the version of the update itself or the resulting firmware version after the update.PowerPC Mac Firmware / Boot ROM Updates by AphoticD, MacRumors. 2021-02-23.
Version	Models 	Startup icon	Notes
1.0.5 	Power Macintosh 7200, 7300 to 9600 	Monochrome 	First released in 1995.
1.1.22 	Apple Network Server 500, 700 	n/a 	No Mac OS booting.
2.0 	Power Macintosh 5400, 6360, 6400 	Monochrome 	
2.0f1 	Power Macintosh G3 (beige, rev.A) 	Color 	
2.0.1 	PowerBook 2400c, 3400c, PowerBook G3 (Kanga, Wallstreet, PDQ) 	Color 	
2.0.2 	Power Macintosh 4400/7220 	Color 	
2.0.3 	Power Macintosh 5500, 6500, 20th Anniversary Macintosh 	Color 	
2.4 	Power Macintosh G3 (beige, rev.B and later) 	Color 	
3.x 	iMac G3 (tray loading), Power Mac G3 (B&W), PowerBook G3 Series (Lombard)	Color 	New World ROMs, updatable.
4.1.7 	iBook G3 (clamshell) 	Color 	Firmware update
4.1.8 	PowerBook G3 Series (Pismo, 2000), Power Mac G4 (Digital Audio, 2001) 	Color 	Firmware update
4.1.9 	iMac G3 (slot loading), Power Mac G4 Cube 	Color 	Firmware update
4.2.0 	iBook G3 (Dual USB, 2001) 	Color 	No USB disk (UD) booting.
4.2.8 	Power Macintosh G4 (Sawtooth) 	Color 	Firmware update
4.2.9 	PowerBook G4 (550 - 667 MHz) 	Color 	Firmware update
4.4.8 	Power Mac G4 (Mirror Drive Doors, 2003) 	Color 	
4.8.6 	PowerBook G4 (2004) 	Color 	
4.8.9 	Mac mini G4 (2005) 	Color 	
4.9.0 	PowerBook G4 (12", 2005) 	Color 	Boot picker support.
4.9.1 	PowerBook G4 (17", 2005) 	Color 	
4.9.3 	iBook G4 (2005) 	Color 	
5.1.4 	Power Mac G5 (2003) 	Color 	Firmware update
5.1.5f2	Power Mac G5 (single processor, 2003) 	Color 	Firmware update
5.2.7 	Power Mac G5 (2005) 	Color 	
===Discontinuation===
Starting in 2006, Apple phased out its use of Open Firmware in favor of EFI (Extensible Firmware Interface) during its transition to Intel processors.
==References==
==See also==
*ROM: Macintosh ROMs
==External links==
*Technical Note 1061: Fundamentals of Open Firmware, Part I at Apple Developer Connection (2000-06-01, mirrored)
**Technical Note 1062: Fundamentals of Open Firmware, Part II (1996-09-01, mirrored)
**Technical Note 1044: Fundamentals of Open Firmware, Part III (2001-06-26, mirrored)
*FirmWorks The Open Firmware Source
*Hardware Independent Boot Code: Open Firmware by M.E. Johnson at Sabaki Engineering (1996, archived 1997-05-02)
*The Open Firmware Wiki by z970mp at MacRumors (2020-02-28)
*Open Firmware at GitHub
*Open Firmware at MorphOS Library
*Open Firmware at the OLPC Wiki
*Open Firmware at OpenBIOS
* at Wikipedia
Category:IEEE standards
Category:Mac OS X
Category:Macintosh firmware