But even if Atom can beat ARM's power/performance efficiency, Apple may not switch iOS to the x86. All those zillions of apps for iPhones and iPads are natively compiled for ARM. Either software developers would have to recompile them for the x86 or Apple would have to provide an ARM-on-x86 emulator. Although Apple has successfully used emulation to smooth the Mac's platform transitions, an emulator's overhead in CPU clock cycles, memory, and power would be a greater burden for a mobile device. Unless an Atom processor can emulate ARM faster than an ARM processor can run its own native code, Apple would have little or no technical reason to switch CPU architectures.
Don't rule out the Steve factor
So far, all this analysis overlooks one vital factor: Steve Jobs. Although Apple's co-founder no longer dwells among the living, his famous "reality-distortion field" radiates from the grave.
Jobs never liked sharing profits with anyone, which is why Apple's platforms are walled gardens. Apple's "curated" model of app-store merchandising exerts almost total control over software distribution while keeping a large slice of the revenue. That model started with iTunes, surged with the iPhone and iPad, and is gradually encompassing the Mac. Now, instead of buying readily available off-the-shelf chips, Apple is designing its own ARM CPU cores and iOS application processors -- difficult projects that cost the company about $500 million for acquisitions, licenses, and engineering just to get the first chip out the door.
In other words, sometimes Apple goes to great lengths to assert control over its platforms and customize its products, never mind the expense. Thus far, the strategy has paid off, making Apple one of the world's largest companies by market capitalization and amassing it $121 billion in surplus cash.
Today, Apple can afford to take risks and go its own way. It would have been characteristic for Jobs to declare his independence from Intel by decreeing that all future Apple products must someday use Apple-designed processors based on Apple's own ARM CPU cores. Even if it wasn't an explicit command, his inheritors may be thinking along the same lines, due to their longtime exposure to his reality-distortion field. Having fathered a few successful application processors, they may now believe they can beat Intel at its own game.
Therefore, you can't rule out that Apple will switch the Mac to ARM or move iOS to the x86. This is not a company that follows the beaten track.
Technically, however, the best bets are that x86 processors will remain the high-performance leaders for desktops, laptops, and servers, while ARM processors will not lose their low-power advantages for mobile devices. Expect the rest of the industry to follow those assumptions until something radically changes. Apple, as it has in the past, could be that radical catalyst.
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