By Jason Snell

February 2, 2017 4:08 PM PT

Apple, ARM, and the coming of the hybrid Mac

Note: This story has not been updated for several years.

There’s been a lot of debate about whether Apple would ditch Intel processors and start making Macs with ARM processors like the ones that power the iPhone and iPad. Those discussions have generally been about a binary choice between Intel and ARM, even after the new MacBook Pro with Touch Bar muddied the waters substantially.

Now here comes a new report by Mark Gurman and Ian King at Bloomberg that suggests the new MacBook Pro could be a bigger clue to the future of the Mac than previously expected. It’s an approach that blows away the binary choice of Intel-versus-ARM and potentially leads the Mac down a product design path that’s quintessentially Apple.

Like every Mac released since 2006, the MacBook Pro with Touch Bar is powered by an Intel-built processor. But the Touch Bar, Touch ID sensor, and front-facing camera on the MacBook Pro are operated by the T1 processor, an Apple-designed ARM processor in the lineage of the chips that power the iPhone, iPad, Apple Watch, and Apple TV. It’s being controlled by an embedded variant of watchOS.

According to Bloomberg, this hybrid approach to building a laptop may be just the beginning:

Apple engineers are planning to offload the Mac’s low-power mode, a feature marketed as “Power Nap,” to the next-generation ARM-based chip. This function allows Mac laptops to retrieve e-mails, install software updates, and synchronize calendar appointments with the display shut and not in use. The feature currently uses little battery life while run on the Intel chip, but the move to ARM would conserve even more power… by connecting to other parts of a Mac’s system, including storage and wireless components, in order to take on the additional responsibilities.

Intel processors have a lot of advantages. They’re built for traditional PC operating systems like the Mac and Windows, and the tasks that big desktop (and laptop) computers work on. The entire Mac software base is compiled for them. The slowest Intel processors Apple uses in the slowest Macs are about as fast as the fastest Apple processors used in Apple’s most advanced iOS devices. Building an ARM-based processor that could power a high-end iMac¹ is probably something Apple could accomplish, but it might not happen anytime soon—and making such a processor might not be a priority for Apple’s development road map.

This report suggests that Apple may instead be investigating the advantages of a hybrid computer, one that can harness the power of the standard Intel processors that every PC maker uses, but combine it with the unique characteristics of Apple’s own ARM processors. You could argue that since 2006, Apple has only been able to differentiate the Mac from the PC based on software and industrial design. If the Mac evolves into a product that’s a combination of Intel and Apple-designed ARM processors, coordinated by Apple’s operating system, that makes the Mac unique—and potentially gives it some major advantages over other PCs.

The strength of the A-series chips found in the iPhone and iPad is that they are incredibly power efficient, optimized for battery-operated devices, while also providing remarkable graphics and processor performance. If you were to list Mac functions that might be offloaded to an ARM processor, Power Nap would be a good place to start, especially if macOS were tuned to be more aggressive about putting the system to sleep.

What would an ARM-Intel hybrid Mac look like? Would whole segments of the operating system run on the ARM processor, allowing the more power-hungry Intel chip to be put to sleep except when it was absolutely needed? There are a bunch of big questions here, most notably the identity of the code that would run on the ARM processor and where it came from. Would Mac apps include extensions or plug-ins that would be designated to run on ARM? Would Mac apps provide two separate sets of program binaries so that the system could switch them between processor architectures at will?

And then there’s the question of what the change would mean for the specs of Apple’s future laptops. Presumably the value of doing all this work would be to create a MacBook or MacBook Pro with vastly improved battery life, because theoretically the more work gets shifted to the power-efficient ARM processor, the more power efficient the entire system gets. If done right, it could give Mac laptops a huge advantage over ones that run Windows—and it would be an advantage that would be much more difficult for competitors to overcome.

(This might also mean that users who truly take advantage of the power of the Intel processors—video editors might be a good example—might continue to find that Apple’s battery-life breakthroughs don’t seem to actually improve battery life for them, because most battery-life improvements have to do with being more power efficient when the computer is idle or doing non-taxing work.)

It’s a weird idea, but I can see the appeal. And this approach allows Apple to dip its toe in the water, experimenting with ARM on the Mac without going all-out and releasing a line of entirely ARM-based Macs. If all goes well, though, it’s hard not to imagine that Apple would eventually do away with the Intel processors altogether… but a hybrid approach would allow that shift to happen over years, rather than all at once.

As for the near future, well, this seems to be the answer to the question, “If Apple’s going to embed a separate processor and operating system in every MacBook Pro, what if they were capable of doing more than just running the Touch Bar?” If this report is accurate, that’s exactly what we’ll see. Maybe the Mac’s future is weirder than we’ve previously imagined.

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