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Apple intern paper hints at full Mac OS X on ARM

updated 05:55 am EST, Tue February 7, 2012

Apple intern details Apple's experiments with ARM

A paper written by a former Apple intern, and now Core OS engineer, has detailed Apple's attempts at getting a full version of Mac OS X to boot on an ARM processor, reports iMore. Initially subject to an embargo, but just recently published, the paper was written as part of a Bachelor degree thesis in 2010 by Tristan Schapp. It details the technical aspects and challenges associated with getting Darwin, which underpins OS X, to work effectively on the ARM architecture.

The publication of the thesis confirms that Apple has indeed been experimenting with the various ways in which it could leverage ARM architecture in its product line. However, at the same time, it does not necessarily point to Apple introducing any MacBook or desktop products running on ARM processors. Just in the past week, a Citigroup analyst Richard Gardner, met with Apple CEO Tim Cook and CFO Peter Oppenheimer and raised the question about whether Apple would indeed launch a MacBook Air powered by an ARM-based processor. Gardner says that he walked away from the meeting with the impression that "Apple feels [the] iPad satisfies -- or will soon satisfy -- the needs of those who might have been interested in such a product."

Rumors first surfaced that Apple was testing an A5-based MacBook Air back in May last year. At the time it was suggested that at the least, Apple was merely testing the concept. Whether Apple was testing an ARM-based version of the Air running a full version of Mac OS X, or whether it was running a variation of iOS tailored for a notebook was not clear at the time. Apple has thus far been inclined bring iOS back to the Mac platform, but it has not given away its hand as to whether it ultimately aims to unify the two related, but still technically different, platforms. One major impediment to running a full version of Mac OS X on ARM in a MacBook Air, even if feasible, would be its inability to support Apple's newly implemented Thunderbolt IO.

Then in August, a fresh rumor surfaced suggesting that Apple was prepping a new Mac line that was expected to be "absolutely different from current products." At the time, it was thought that this could indeed be a MacBook Air line fitted with ARM-based processors. Microsoft's decision to release a version of Windows 8 that will boot on ARM-based processors has also further fueled speculation that Apple might do likewise. However, unless Apple has been secretly reworking a fully-touch optimized version of Mac OS X, in the same way that Windows 8 has been touch and tablet optimized, it again seems unlikely that it will pursue this path.

An example of whether there is even a compelling necessity to do so has been the runaway success of the iPad, running its lightweight mobile OS. It has defied the critics who derided it for being incapable of carrying out all the tasks of a regular computer. Despite this, what it does, rather than what it doesn't, seems to have been convincing enough that Apple may not need to further pursue a full version of Mac OS X on ARM to counter any potential threat from Windows 8.

By Electronista Staff
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  1. facebook_Philippe

    Via Facebook

    Joined: Feb 2012



    This isn't exactly earth shattering news.
    I am pretty sure there also are papers from other students who worked on MIPS. itanium, Power , obscure processors, versions of the same.
    Steve Jobs once said that Apple likes to have options when it comes to the silicon they use.
    I don't think his passing has changed this in any way..

  1. Peter Bonte

    Fresh-Faced Recruit

    Joined: Aug 2001


    Keeping options open

    Apple developed OSX simultaneously on PPC and Intel to keep the code clean, that way they could migrate to Intel when needed. I'm guessing Apple still codes to PPC/ARM for the same reason, in 5 years ARM chips could well be overpowering Intel by a factor of 4 based on energy use. Right now i don't see this happening but never say never.

  1. qazwart

    Fresh-Faced Recruit

    Joined: Apr 2001


    Isn't iOS Already on ARM?

    When Apple first came out with the iPhone, they called the OS "OS X for the iPhone". This was later rebranded "iPhone OS" and later "iOS".

    Apple is lucky that Mac OS X was developed upon NeXT OS which itself was based upon BSD and Mach 2.0 which were built to be hardware agnostic. This allowed Apple to switch from PPC to Intel and quietly develop a whole new version of Mac OS technologies for ARM based processors.

    Yes, it's not the entire Mac OS X on ARM with iOS, but the generic underpinnings are the same. The main difference is the very top layer that the user sees. Plus, many of the services that were removed from iOS to save memory and power.

    Putting the whole Mac OS X on an ARM chip is a great exercise for an intern who will be responsible for Core OS services. It lets the intern get their hands dirty learning the ins and outs of the OS that's the basis of both operating systems.

    One day, the Mac and iOS will merge. Maybe in a decade, maybe in five years. ARM based chips are getting more powerful, and maybe Intel will get its act together and make an x86 based portable chip. So, maybe making sure that Mac OS X can run on an ARM chip is also a way for Apple to make that leap when it needs to. However, that day isn't going to be next year.

    An ARM chip, when compared to the quad-core Intel is much slower and less powerful. However, ARM is more efficient. Remember we're talking about not necessarily the chip, but the command set the chip uses. x86 is a true 64 bit set of instructions, it is bigger than ARM's instruction set and more powerful.

    ARM's big power is that it's efficient because it was built for embedded systems, and it's licensable. Thus a lot of companies (including Apple) have licensed the architecture and instruction set building their own "ARM" chips.

    NVidia Project Denver is an attempt to build a powerful ARM chip for the desktop that can focus on graphics performance. Maybe if Project Denver comes through, we might see some Macs based upon these NVidia chips.

  1. BigMac2

    Forum Regular

    Joined: Dec 2000


    Badly edited news

    This article as missed a key information, the real news was about porting on iPod classic ARMv5 CPU instead of the ARMv6 of the original iPhone.

    here is a more complete story:

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