PowerPC Platform

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PowerPC Platform , PPCP for short , is a specification for PowerPC -based personal computers (PCs) that was developed by Apple , IBM and Motorola (AIM alliance). It was published on November 14, 1995 under the old name Common Hardware Reference Platform , CHRP for short (pronounced chirp , from English to chirp , 'chirp', 'chirp'). The specification describes a standard for the design of motherboards for computers with PowerPC processors. Since the PowerPC Platform is designed as an open specification, several operating systems can be operated on one CHRP-compliant computer.

CHRP followed the PowerPC Reference Platform ( PReP for short ) from 1994 and was renamed the PowerPC Platform specification (PPCP) at the end of 1995 .

Another common name is PowerPC Open Platform (POP) .

The Power Architecture Platform Reference , PAPR for short, developed by Power.org in 2006 , completely replaces PPCP.


CHRP is the collective name for a hardware platform with Apple, IBM and Motorola (also known as AIM -Allianz) at that time based on the technology of the RS / 6000 - microcomputers (POWER architecture) a standard for PowerPC-based desktops wanted to establish. CHRP / PPCP is a superset of PReP from IBM and Power Macintosh from Apple.

For Apple, the PReP standard laid down by IBM in 1994 was too PC-heavy, since it was essentially IBM PC hardware with a PowerPC processor. With CHRP, on the other hand, the Open Firmware (IEEE-1275) used by Apple is just as much a part of the specification as the Macintosh-typical serial interfaces and ADB .

Both PReP operating systems and Macintosh operating systems can run on a CHRP-compliant system. However, Apple's System 7.5 , renamed Mac OS in 1997 , was not CHRP compliant. Only Copland - announced as the upcoming System 8 or Mac OS 8 - should have become a CHRP operating system, but was stopped unfinished in early 1997. In the meantime, CHRP hardware has been used by manufacturers of various PowerPC computers, among others. a. some Macintosh clone manufacturers announced. CHRP operating systems, including AIX from IBM and Windows NT from Microsoft , also became available. At demo 96 , which took place in week 5 1996, Apple promised a CHRP-compliant Mac OS in the second half of 1996.


Apple, manufacturer of the Power Macintosh computer family, moved away from this open platform again in 1997 due to strategic market and technical considerations. The fear was that it would lose further ground in hardware sales. During this time, Apple received a new operating system with the takeover of NeXT and soon also a change of leadership, as Steve Jobs was again CEO of Apple in 1997. The strategy of the open platform, which Apple had embarked on with the sale of licenses for System 7 or Mac OS 7.6 and with the planned multi-platform operating system Copland, was not pursued any further, because on the virtually constant market for Power Macintosh-compatible Desktops had only shrunk Apple's share because of the licensed clones.

As a result, CHRP-compatible Macintosh clones from other manufacturers also disappeared from the market by the end of the 1990s. After 1997, Apple's PowerPC developments initially took a more proprietary direction again. Only the tried and tested approach of Open Firmware (IEEE-1275) remained visible , the function of which corresponds to the BIOS in IBM-compatible PCs. Power Macs were therefore never CHRP-compliant and PowerPC operating systems other than Linux / PPC did not run on Macs. The promised CHRP-compliant Mac OS, which should also have run on other CHRP computers, also failed to materialize. At the beginning of 2006 Apple completely turned away from the PowerPC platform and instead developed x86-based systems - “Intel Macs” - based on Mac OS X , which use the competing firmware approach EFI from Intel.

With the Pegasos computer family and architecture from Genesi and Linux / PPC, IBM and Motorola (from 2004 Freescale , which was finally taken over by NXP in 2015 ) meanwhile once again have a powerful reference platform for the PowerPC. Genesi viewed the IEEE 1275-compatible Pegasos HAL / OF (Hardware Abstraction Layer / Open Firmware ) as the logical successor to the CHRP standard and offered a corresponding licensing program (nominal license fee per unit). Consequently, information on the design and the required components for the Pegasos hardware itself was available for free download under the heading "Open Hardware". It is unclear to what extent the successor, the Pegasos-II, was RoHS- compliant.


From IBM and Freescale computers from the Pegasos family were available as development platforms under the name “ODW” ( Open Desktop Workstation with G3 and G4 ) and from 2006 also “OSW” (Open Server Workstation with G5 ). However, the development goals were fewer desktop computers than z. B. Embedded systems in focus.

Also - about ten years after the last Amiga models, which were still being developed under the direction of Commodore - the British company Eyetech (using the Teron motherboard as a reference design) had new variants developed with their own specifications. These operated under the name AmigaOne and are also CHRP-compliant. The original Teron design by Mai Logic is based on the specifications released by IBM in 2000 for a complete CHRP motherboard including a generic design, known under the name POP already mentioned above .

Web links

Individual evidence

  1. Ken Polsson: Chronology of IBM Personal Computers. 1992-1995. April 29, 2017, accessed on July 23, 2017 (English): "1995, November 14: IBM, Apple Computer, and Motorola release the PowerPC Platform specifications, called the Common Hardware Reference Platform (CHRP). It encompasses support for Macintosh System 7, Windows NT, AIX, Solaris, NetWare, and OS / 2. Windows 3.x and Windows 95 are excluded. "
  2. Carsten Meyer: New name, new luck - Apple, IBM and Motorola present “PowerPC Platform”. In: Heise online . December 12, 1995 . Retrieved July 23, 2017.
  3. CHRP vendors may leave Apple behind. Vendors may ship CHRP computers before Apple does, using beta versions of Mac OS. In: News. CNET , July 12, 1996, accessed July 23, 2017 .
  4. Geoff Duncan: Apple Demos Mac OS on PPCP. TidBITS Publishing Inc., February 5, 1996, accessed July 23, 2017 .
  5. Eric Murphy: New PowerPC Platform in Fruition. TargetPC.com, December 26, 1999, accessed on July 23, 2017 (English): “… technical issues caused delay after delay, and most were caused by Apple, as they attempted to free the Mac OS from its ROM dependencies, and pondered whether the PowerPC Platform would help them or hurt them. ... Suddenly and swiftly, Apple killed Mac OS for the PowerPC Platform along with the Mac cloning licenses, effectively smothering the open platform ideology. "