XPostFacto
Encyclopedia
XPostFacto is an open source
utility that enables the installation of PowerPC
versions of Mac OS X
up to Mac OS 10.4 (Tiger), and Darwin (operating system)
on some PowerPC-based Apple Macintosh systems that are not officially supported for them by Apple
.
XPostFacto - often referred to as "XPF" - runs under Mac OS 9
and allows an unmodified Mac OS X installation disc to be launched on machines which cannot boot Mac OS X unaided. This allows Mac OS X to be installed on certain Mac models which could otherwise only run System 7
, Mac OS 8
or Mac OS 9
, albeit sometimes with incomplete functionality. For example, it can be used to install Mac OS X v10.2
on a PowerPC 604 equipped Power Macintosh
8600 or 9600.
It also allows more recent versions of Mac OS X to be installed on older G3 Macs which can only officially run earlier versions of OS X - for example, it allows Mac OS X v10.3
and Mac OS X v10.4
to run successfully on Beige G3s, 10.2 having been the last version supported by Apple. It can even facilitate otherwise-awkward installations on supported machines; for instance, it allows Mac OS X v10.4
, which shipped on DVD
media, to be installed onto a Blue and White G3 with only an external, non-bootable DVD drive. Likewise, Mac OS X 10.4 Tiger ended support for machines that lacked built-in FireWire ports, these being the original iMac G3
s and iBook G3s, but XPostFacto allows the use of 10.4 on them.
The name is a pun
on ex post facto, a Latin
phrase meaning "after the fact", commonly used in legal matters to refer to retroactive actions applying a later state of affairs (such as legislation) to earlier situations. In this context, it refers to the installation of software which did not exist yet at the time the hardware was manufactured: it retroactively "applies" Mac OS X to pre-existing hardware.
This software engineering feat by developer Ryan Rempel is made possible by the publication of the source code for Darwin
, the open-source foundation of Mac OS X.
XPF's functionality is achieved via three different routes. The program provides a replacement boot loader for Macs with OldWorld firmware
, provides a set of kernel modules to allow the Mac OS X kernel to support various pieces of system hardware which are unsupported in the retail release, and includes a mechanism to transparently boot the kernel off a supported medium - termed a "helper drive", such as the internal hard disk - even when installing Mac OS X to or from a non-bootable volume, such as a USB optical drive or a hard disk
which is unsupported by the kernel or system firmware.
XPF does not support all models of Power Macintosh
. Only certain PCI-based models with Open Firmware
will work. It does not support NuBus
-based PowerMacs.
Once Mac OS X has been installed, XPF also runs under that operating system
. On unsupported machines, XPF should be used instead of Apple's "Startup Disk" control panel or system preference pane to select whether the Mac should boot into Mac OS X or an older version.
Although experimental versions of XPF were available before the release of Mac OS X v10.2, v10.3 and v10.4, no version was available at the time of the release of v10.5 and XPF 4 does not support Mac OS X v10.5. XPostFacto is not required to run v10.5 on unsupported Macs as long as they have a G4 processor and AGP graphics, the official requirement of an 867 MHz G4 processor only needs to be bypassed at the time of installation and once installed Leopard will run without problems or requiring XPostFacto. On Macs that have only PCI graphics though, such as the Beige G3, the version of XPostFacto intended for use with OS X 10.4 needs to be used in order to boot 10.5 successfully (provided that it has been upgraded to a G4 processor as Leopard will not run at all on G3s), although it cannot be used to actually install the operating system as it does not recognise the 10.5 DVD (another machine would have to be used for the installation and then the hard drive transferred into the unsupported machine).
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
utility that enables the installation of PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
versions of Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
up to Mac OS 10.4 (Tiger), and Darwin (operating system)
Darwin (operating system)
Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000. It is composed of code developed by Apple, as well as code derived from NeXTSTEP, BSD, and other free software projects....
on some PowerPC-based Apple Macintosh systems that are not officially supported for them by Apple
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
.
XPostFacto - often referred to as "XPF" - runs under Mac OS 9
Mac OS 9
Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
and allows an unmodified Mac OS X installation disc to be launched on machines which cannot boot Mac OS X unaided. This allows Mac OS X to be installed on certain Mac models which could otherwise only run System 7
System 7
System 7 is the name of a Macintosh operating system introduced in 1991.System 7 may also refer to:* System 7 , a British dance/ambient band* System 7 , 1991 album* IBM System/7, a 1970s computer system...
, Mac OS 8
Mac OS 8
Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It represented the largest overhaul of the Mac OS since the release of System 7, some six years previously. It puts more emphasis on color than previous operating systems...
or Mac OS 9
Mac OS 9
Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
, albeit sometimes with incomplete functionality. For example, it can be used to install Mac OS X v10.2
Mac OS X v10.2
Mac OS X version 10.2 "Jaguar" is the third major release of Mac OS X, Apple's desktop and server operating system. It superseded Mac OS X v10.1 code name Puma and preceded Mac OS X Panther...
on a PowerPC 604 equipped Power Macintosh
Power Macintosh
Power Macintosh, later Power Mac, was a line of Apple Macintosh workstation-class personal computers based on various models of PowerPC microprocessors that were developed, marketed, and supported by Apple Inc. from March 1994 until August 2006. The first models were the Power Macintosh 6100,...
8600 or 9600.
It also allows more recent versions of Mac OS X to be installed on older G3 Macs which can only officially run earlier versions of OS X - for example, it allows Mac OS X v10.3
Mac OS X v10.3
Mac OS X Panther is the fourth major release of Mac OS X, Apple’s desktop and server operating system. It followed Mac OS X v10.2 "Jaguar" and preceded Mac OS X Tiger...
and Mac OS X v10.4
Mac OS X v10.4
Mac OS X v10.4 Tiger is the fifth major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. Tiger was released to the public on 29 April 2005 for US$129.95 as the successor to Mac OS X Panther , which had been released 18 months earlier...
to run successfully on Beige G3s, 10.2 having been the last version supported by Apple. It can even facilitate otherwise-awkward installations on supported machines; for instance, it allows Mac OS X v10.4
Mac OS X v10.4
Mac OS X v10.4 Tiger is the fifth major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. Tiger was released to the public on 29 April 2005 for US$129.95 as the successor to Mac OS X Panther , which had been released 18 months earlier...
, which shipped on DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
media, to be installed onto a Blue and White G3 with only an external, non-bootable DVD drive. Likewise, Mac OS X 10.4 Tiger ended support for machines that lacked built-in FireWire ports, these being the original iMac G3
IMac G3
The iMac G3 was the first model of the iMac line of personal computers made by Apple Inc. , and the originator of the Legacy-free PC market category. Like the first Macs, the iMac G3 is an all-in-one personal computer, encompassing both the monitor and the system unit in a single enclosure...
s and iBook G3s, but XPostFacto allows the use of 10.4 on them.
The name is a pun
Pun
The pun, also called paronomasia, is a form of word play which suggests two or more meanings, by exploiting multiple meanings of words, or of similar-sounding words, for an intended humorous or rhetorical effect. These ambiguities can arise from the intentional use and abuse of homophonic,...
on ex post facto, a Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
phrase meaning "after the fact", commonly used in legal matters to refer to retroactive actions applying a later state of affairs (such as legislation) to earlier situations. In this context, it refers to the installation of software which did not exist yet at the time the hardware was manufactured: it retroactively "applies" Mac OS X to pre-existing hardware.
This software engineering feat by developer Ryan Rempel is made possible by the publication of the source code for Darwin
Darwin (operating system)
Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000. It is composed of code developed by Apple, as well as code derived from NeXTSTEP, BSD, and other free software projects....
, the open-source foundation of Mac OS X.
XPF's functionality is achieved via three different routes. The program provides a replacement boot loader for Macs with OldWorld firmware
Firmware
In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices...
, provides a set of kernel modules to allow the Mac OS X kernel to support various pieces of system hardware which are unsupported in the retail release, and includes a mechanism to transparently boot the kernel off a supported medium - termed a "helper drive", such as the internal hard disk - even when installing Mac OS X to or from a non-bootable volume, such as a USB optical drive or a hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
which is unsupported by the kernel or system firmware.
XPF does not support all models of Power Macintosh
Power Macintosh
Power Macintosh, later Power Mac, was a line of Apple Macintosh workstation-class personal computers based on various models of PowerPC microprocessors that were developed, marketed, and supported by Apple Inc. from March 1994 until August 2006. The first models were the Power Macintosh 6100,...
. Only certain PCI-based models with Open Firmware
Open Firmware
Open Firmware, or OpenBoot in Sun Microsystems parlance, is a standard defining the interfaces of a computer firmware system, formerly endorsed by the Institute of Electrical and Electronics Engineers . It originated at Sun, and has been used by Sun, Apple, IBM, and most other non-x86 PCI chipset...
will work. It does not support NuBus
NuBus
NuBus is a 32-bit parallel computer bus, originally developed at MIT as a part of the NuMachine workstation project. The first complete implementation of the NuBus and the NuMachine was done by Western Digital for their NuMachine, and for the Lisp Machines Inc. LMI-Lambda. The NuBus was later...
-based PowerMacs.
Once Mac OS X has been installed, XPF also runs under that operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
. On unsupported machines, XPF should be used instead of Apple's "Startup Disk" control panel or system preference pane to select whether the Mac should boot into Mac OS X or an older version.
Although experimental versions of XPF were available before the release of Mac OS X v10.2, v10.3 and v10.4, no version was available at the time of the release of v10.5 and XPF 4 does not support Mac OS X v10.5. XPostFacto is not required to run v10.5 on unsupported Macs as long as they have a G4 processor and AGP graphics, the official requirement of an 867 MHz G4 processor only needs to be bypassed at the time of installation and once installed Leopard will run without problems or requiring XPostFacto. On Macs that have only PCI graphics though, such as the Beige G3, the version of XPostFacto intended for use with OS X 10.4 needs to be used in order to boot 10.5 successfully (provided that it has been upgraded to a G4 processor as Leopard will not run at all on G3s), although it cannot be used to actually install the operating system as it does not recognise the 10.5 DVD (another machine would have to be used for the installation and then the hard drive transferred into the unsupported machine).