Mac transition to Intel processors
The Mac transition to Intel processors was the process of changing the central processing unit (CPU) of Apple Inc.'s line of Mac computers, as well as its server offerings at the time, from PowerPC to Intel x86 processors.

The change was announced at the 2005 Worldwide Developers Conference (WWDC) by then-Apple CEO Steve Jobs, who said Apple would gradually stop using PowerPC microprocessors supplied by Freescale (formerly Motorola) and IBM.

This was the second time Apple changed the processor instruction set architecture of its personal computers. The first was in 1994, when Apple discarded the Mac's original Motorola 68000 series architecture in favor of the then-new PowerPC platform.

Apple's initial press release said the move would begin by June 2006 and finish by the end of 2007, but it actually proceeded much more quickly. The first-generation Intel-based Macintoshes were released in January 2006 with Mac OS X 10.4.4 Tiger. In August, Jobs announced the last models to switch, with the Mac Pro available immediately and the Intel Xserve available by October (it actually shipped in December).

The final version of Apple's Mac OS that ran on PowerPC chips was 2007's Leopard (version 10.5), released in October 2007. The final version to run applications written for PowerPC chips, using the Rosetta binary translator, was 2009's Snow Leopard (version 10.6). Mac OS X Lion (version 10.7) dropped support altogether.

In 2020, Apple announced that it would shift its Mac line to Apple silicon, which are ARM-based processors developed in-house.

Background

Apple had been using PowerPC processors in its products for 11 years when the move to Intel processors was announced.

At 2003's WWDC keynote address, Jobs unveiled a Power Mac with a processor from IBM's PowerPC G5 product line, the first personal computer to feature a 64-bit processor.

He promised a 3 GHz Power Mac G5 within 12 months, but never released such a product. In 2004's WWDC keynote address, Jobs addressed the broken promise, saying IBM had trouble moving to a fabrication process lower than the 90 nm process. Apple officials also said in 2003 they planned to release a PowerBook with a G5 processor, but such a product never materialized. Tim Cook, then Apple's Executive Vice President of Worldwide Sales and Operations, said during an earnings call that putting a G5 in a PowerBook was "the mother of all thermal challenges".

In addition, there were reports that IBM officials had concerns over the profitability of a low-volume business, which caused tensions with Apple and its desires for a wide variety of Power PC processors.

History

1980s
Apple's efforts to move to Intel hardware began in 1985. A proposal was floated after Jobs departed but was quickly disapproved by management.

1990s
The first known attempt by Apple to move to Intel's platform was the Star Trek project, a code name given to a secret project to run a port of Classic Mac OS System 7 and its applications on an Intel-compatible personal computer. The effort began on February 14, 1992, with the blessing of Intel's then-CEO Andy Grove.

Apple leaders set an October 31 deadline to create a working prototype. The team met that deadline, and had a functional demo ready by December. John Sculley's departure during the Star Trek project was a factor in the project's termination. Michael Spindler, who took over as Apple's CEO, devoted most of Apple's resources to moving to PowerPC instead, thus initiating Apple's first processor transition.

After Apple's 1997 acquisition of NeXT, Apple began to rework their NeXTSTEP operating system into a successor to the classic Mac OS, codenamed Rhapsody. Jobs (who rejoined Apple upon the purchase) demonstrated an Intel-compatible build of Rhapsody to Dell founder and namesake Michael Dell. Jobs offered to license the new OS to Dell for its PCs, so that users could choose between it and Windows. However, Dell declined when Jobs insisted that the company license the operating system for every PC it ships, regardless of whether or not the user wanted to use Mac OS.

Early 2000s

In the years since the end of the Star Trek project, there were reports of Apple working to port its operating system to Intel's x86 processors, with one engineer managing to get Apple's OS to run on a number of Intel-powered computers.

In 2001, Jobs and then Sony president Kunitake Andō reportedly had a meeting to discuss the possibility of running Apple's operating system on its Vaio computers. Jobs even presented a Vaio running Mac OS. Such negotiations ultimately came to nothing.

In 2002, it was reported that Apple had more than a dozen software engineers tasked to a project code-named "Marklar," with a mission to steadily work on maintaining PC-compatible builds of Mac OS X.

It was noted in 2003 by IBM in an article published to its intranet that Apple felt a transition to Intel presents massive software changes that it wanted to avoid. Nevertheless, rumors of an impending announcement of a transition to Intel cropped up in 2000 and 2003.

2005
News reports of an impending announcement by Apple to transition to Intel processors surfaced in early June 2005, close to that year's WWDC. The announcement was made during that year's WWDC Keynote Address.

At the time Apple announced the transition, Jobs attributed the switch to a superior product roadmap that Intel offered, as well as an inability to build products envisioned by Apple based on the PowerPC product roadmap. Meanwhile, pricing disputes with IBM, in addition to a desire by Apple to give its computer the ability to run Microsoft Windows, were reportedly factors for the switch as well.

Reaction to the change
At the time, a research director for Ovum Ltd. called the move "risky" and "foolish", noting that Intel's innovation in processor design is overshadowed by both AMD and IBM. Another analyst said the move risks diluting Apple's value proposition, since it will now have less control over its product road map, in addition to the risk of alienating its loyal users.

AMD
Some observers expressed surprise that Apple made a deal with Intel instead of with AMD. By 2005, AMD had become popular with gamers and the budget conscious, but some analysts believed AMD's lack of low-power designs at the time was behind Apple's decision to go with Intel.

In 2011, Apple investigated using AMD's low power Llano APU for the MacBook Air, but eventually opted for Intel due to AMD's potential inability to supply enough Llano processors to meet demand.

32-bit regression
Apple had created the world's first consumer 64-bit desktop computer with its G5 based line-up, however the first Intel-based Macs included only Intel Core Duo processors, which were 32-bit. Apple refreshed its line of computers six months later, adding Intel's new Intel Core 2 Duo 64-bit processors.

Concerns over Rosetta performance
When Rosetta was announced, it was noted that the translation software is designed to translate applications that run on a "PowerPC with a G3 processor and that are built for Mac OS X." It was noted at the time that translated software performs at a level between 50% to 80% of native software. The announcement caused concerns over performance.

Intel
At the time the transition was announced, it was noted that a degree of enmity towards Intel exists amongst some fans of Apple products, due to Intel's close identification with Microsoft. In addition, It was noted by Intel's then CEO, Paul Otellini, that Apple and Intel's relationship were strained at times, especially due to Apple's commission of an ad that shows Intel processors being outperformed by PowerPC processors.

While there were questions over whether Apple would put the Intel Inside stickers on its products, Jobs dispelled such a possibility, saying it is redundant when Apple's use of Intel processors is well-known. "Intel Inside" stickers have never been included on any Apple product.

Osborne Effect
There was concern that an early announcement of the change would cause an Osborne effect, but it was also noted that even if an Osborne effect appeared, it would merely mean delayed purchases of Mac computers, not permanent cancellations, and that Apple had enough cash on hand to weather the potential sales  decline.

Analysis of financial data suggests that the Osborne Effect did not materialize, with sales for Macs growing by 19% and 37% in the two quarters following March 2006.

Product compatibility
Classic environment, the Mac OS 9 virtualization measure for Mac OS X, was not ported to the x86 architecture, leaving the new Intel-powered Macs incompatible with original Mac OS applications without a proper third-party PowerPC emulator.

There were also concerns over third-party software support, with reaction to the change being mixed amongst the software developer community, due to a need to recompile software for compatibility on Intel-based Macs. In early 2006, it was reported that a number of software companies, such as Adobe, Aspyr and Microsoft, were not ready to release universal binary versions of their software offerings.

Technical issues
In the years prior to Apple's announcement of the transition, it was noted that there was a debate over the difference of endianness between Intel and non-Intel processors, as well as the merits of each CPU architecture. The difference in endianness meant that some software could not simply be recompiled; it required changes to make it work on processors of either endianness.

Transition process

2005
During Apple's 2005 WWDC, the company introduced a Developer Transition Kit consisting of a prototype Intel-based Mac computer, along with preliminary versions of Mac OS X Tiger and Xcode, which allowed developers to prepare future versions of their software to run on both PowerPC and Intel-based Macs.

To allow apps built for PowerPC-based Macs to run on Intel-based Macs without recompilation, a dynamic binary translation software called Rosetta was created.

2006
On January 10, Apple unveiled an Intel-based iMac, as well as a 15-inch MacBook Pro laptop, which replaced the similarly sized PowerBook.

On February 28, a Mac mini featuring an Intel Core Duo processor was unveiled.

On April 5, the dual-boot software Boot Camp was released as a trial version, which allowed Intel-based Mac owners to run Mac OS X and Microsoft Windows. On April 24, a MacBook Pro replacement for the 17-inch PowerBook was announced.

On May 16, a replacement for the iBook, called MacBook, was announced, thus completing the transition of Apple's laptop line to Intel processors.

On July 5, a replacement for the eMac, a special education configuration of a 17-inch iMac, was announced.

On August 7, Apple unveiled a replacement for the PowerMac, Mac Pro, and an Intel-based version of Xserve. The unveiling of the Mac Pro was touted by Apple as a completion of its transition to Intel, and said the entire process took 210 days.

Ongoing support for PowerPC following transition
The first macOS to require a Mac with Intel processors, thus dropping support for PowerPC-based Macs, was 10.6 Snow Leopard. Snow Leopard was shipped in August 2009, three years after the transition was complete. Support for Rosetta was dropped from macOS on 10.7 Lion, which was released in July 2011. By that point, five years had passed since the transition to Intel was complete.

The last Apple app to feature support for PowerPC processors was iTunes 10.6.3, which was released on June 11, 2012.

Apple has a policy of placing products that have not been sold for more than five years, but less than seven years, on "vintage" status, meaning hardware services from Apple service providers, including Apple Stores, are subjected to availability of inventory, or as required by law. A product is considered obsolete after it has not been sold for more than seven years, which also stops hardware support. Based on this policy, all PowerPC-based Macs are now considered obsolete.

In spite of the PowerPC architecture now being considered obsolete, use of the systems remains popular in retrocomputing; multiple community projects exist that aim to allow PowerPC Macs to carry out modern tasks, such as the Classilla and TenFourFox web browsers.

Legacy
A Mashable article in 2016 noted that the decision to switch to Intel processors gave many people who wanted a Mac, but couldn't commit to giving up Windows, a way to have both via Boot Camp and a number of virtualization programs, and that Mac, as a computer platform, had a renaissance following the transition, with more apps being developed. The article also said following the transition to Intel, Mac, while still outsold by Windows and other computer systems, has had a remarkable comeback, and also noted that Mac users tend to be loyal to the Apple ecosystem, which leads to purchases of other Apple products such as iPad, iPhone and Apple Watch.

On June 22, 2020, Apple announced plans to transition the Macintosh to ARM processors over a two-year period, following a roadmap similar to the Intel transition, including universal binaries and a Rosetta 2 compatibility program. Apple had been using ARM in its other products and designing its own ARM chips for many years.

Timeline
June 6, 2005: Apple announces its plans to switch to Intel processors at the Worldwide Developer Conference and released a Developer Transition System, a PC running an Intel build of Mac OS X 10.4.1 with a Trusted Platform Module in a modified Power Mac G5 case, to all Select and Premier members of the Apple Developer Connection at a price of $999.
 January 10, 2006: Jobs announces the first two computers in this series, the 15" MacBook Pro and iMac Core Duo line, both using an Intel Core Duo chip and offers to trade in the Developer Transition Kits for iMacs.
 February 28, 2006: Jobs announces that the Mac mini now also comes with an Intel Core chip, in either the Solo or Duo varieties.
 April 5, 2006: Apple announced the release of Boot Camp, which allowed users of Intel-based Macs to run Windows XP (and later versions of Boot Camp allow later versions of Windows).
 April 24, 2006: Apple announces the 17" MacBook Pro, replacing the 17" PowerBook.
 April 27, 2006: Intel announces that processors with the Core microarchitecture would be released months sooner than previously thought.
 May 16, 2006: Apple announces the 13" MacBook, replacing both the iBook line and the 12" PowerBook.
 June 26, 2006: Intel announces the Xeon 5100 series server/workstation CPU.
 July 5, 2006: Apple announces a special educational configuration of the iMac, replacing the old G4 eMac.
 August 7, 2006: "Transition Complete" - Apple announces the Intel-based Mac Pro and Xserve, replacing the Power Mac G5 and Xserve G5, at the Worldwide Developers Conference; both use the Xeon 5100 series ("Woodcrest") processors.
 October 26, 2007: Apple ships Mac OS X 10.5 "Leopard", the final release with PowerPC support. Macs using a G3 processor cannot boot this operating system, as only G4 and G5 processors with a minimum 867 MHz clock speed are supported.
 August 28, 2009: Apple ships Mac OS X 10.6 "Snow Leopard" exclusively for Intel Macs. PowerPC Macs cannot boot this OS. This is also the final release with Rosetta, allowing PowerPC software to run on an Intel Mac.
 March 1, 2011: The beta version of the then-upcoming Mac OS X Lion drops "Rosetta" and will not be able to run PowerPC based software.
 June 23, 2011: Support for Mac OS 10.5 Leopard comes to a end, formally ending Apple's support of PowerPC on Mac OS X.
 July 20, 2011: The release of Mac OS X 10.7 Lion formally ends Apple's support of PowerPC-based software.
 August 7, 2011: PowerPC hardware reaches "vintage" status having been discontinued five years earlier, ending most of Apple's service and parts support for PowerPC hardware.
 June 11, 2012: Apple releases iTunes 10.6.3, their last application with support for PowerPC processors.
 August 7, 2013: PowerPC hardware reaches "obsolete" status having been discontinued seven years prior, ending all of Apple's service and parts support for PowerPC hardware.

See also
 Hackintosh
 Star Trek project
 Universal binary
 Mac transition to Apple silicon

References

External links 
 Apple Universal Binary Programming Guidelines
 Can Developers Give Mactel an Enterprise Boost?
 Boot Camp, Apple's solution to running Windows operating systems via a dual-boot method

Macintosh platform
Intel