When Apple announced its 64-bit A7 processor, I dismissed the speculation that this could lead to a switch away from Intel chips for the Macintosh line for a homegrown “desktop-class” chip. I might have been wrong.

“I don’t know exactly when, but sooner or later, Macs will run on Apple-designed ARM chips.” Thus spake Matt Richman in a 2011 blog post titled “Apple and ARM, Sitting in a Tree”. Richman explained why, after a complicated but ultimately successful switch from PowerPC chips to Intel processors in 2005, Apple will make a similar switch, this time to ARM-based descendants of the A4 chip designed by Apple and manufactured by Samsung.

Cost is the first reason invoked for the move to an An processor:

“Intel charges $378 for the i7 chip in the new high-end 15 inch MacBook Pro. They don’t say how much they charge for the i7 chip in the low-end 15 inch MacBook Pro, but it’s probably around $300. …When Apple puts ARM-based SoC’s in Macs, their costs will go down dramatically. ”

We all know why Intel has been able to command such high prices. Given two microprocessors with the same manufacturing cost, power dissipation, and computing power, but where one runs Windows and the other doesn’t, which chip will achieve the higher market price in the PC market? Thus, Intel runs the table, it tells clone makers which new x86 chips they’ll receive, when they’ll receive them, and, most important, how much they’ll cost. Intel’s margins depend on it.

ARM-based processors, on the other hand, are inherently simpler and therefore cost less to make. Prices are driven even lower because of the fierce competition in the world of mobile devices, where the Wintel monopoly doesn’t apply.

Cost is the foremost consideration, but power dissipation runs a close second. The aging x86 architecture is beset by layers of architectural silt accreted from a succession of additions to the instruction set. Emerging media formats demand new extensions, while obsolete constructs must be maintained for the sake of Microsoft’s backward compatibility religion. (I’ll hasten to say this has been admirably successful for more than three decades. The x86 nickname used to designate Wintel chips originates from the 8086 processor introduced in 1978 — itself a backward-compatible extension of the 8088…)

Because of this excess baggage, an x86 chip needs more transistors than its ARM-based equivalent, and thus it consumes more power and must dissipate more heat.

Last but not least, Richman quotes Steve Jobs:

“I’ve always wanted to own and control the primary technology in everything we do.”

Apple’s leader has often been criticized for being too independent and controlling, for ignoring hard-earned industry wisdom. Recall how Apple’s decision to design its own processors was met with howls of protest, accusations of arrogance, and the usual predictions of doom.

Since then, the interest for another Grand Processor Switch has been alive and well. Googling “Mac running on ARM” gets you close to 10M results. (When you Bing the same query, you get 220M hits — 22x Google’s results. SEO experts are welcome to comment.)

Back to the future…

In September 2013, almost a year ago already, Apple introduced the 64-bit A7 processor that powers new iPhones and iPads. The usual suspects pooh-poohed Apple’s new homegrown CPU, and I indulged in a little fun skewering the microprocessor truthers: 64 bits. It’s Nothing. You Don’t Need It. And We’ll Have It In 6 Months. Towards the end of the article, unfortunately, I dismissed the speculation that Apple An processors would someday power the Mac. I cited iMacs and Mac Pros — the high end of the product line — as examples of what descendants of the A7 couldn’t power.

A friend set me straight.

In the first place, Apple’s drive to own “all layers of the stack” continues unabated years after Steve’s passing. As a recent example, Apple created its own Swift programming language that complements its Xcode IDE and Clang/LLVM compiler infrastructure. (For kremlinology’s sake I’ll point out that there is an official Apple Swift blog, a first in Apple 2.0 history if you exclude the Hot News section of the of apple.com site. Imagine what would happen if there was an App Store blog… But I digress.)

Secondly, the Mac line is suspended, literally, by the late delivery of Intel’s Broadwell x86 processors. (The delay stems from an ambitious move to a bleeding edge fabrication technology that shrinks the basic building block of a chip to 14 nanometers, down from 22 nanometers in today’s Haswell chips.) Of course, Apple and its An semiconductor vendor could encounter similar problems — but the company would have more visibility, more control of its own destiny.

Furthermore, it looks like I misspoke when I said an An chip couldn’t power a high-end Mac. True, the A7 is optimized for mobile devices: Battery-optimization, small memory footprint, smaller screen graphics than an iMac or a MacBook Pro with a Retina display. But having shown its muscle in designing a processor for the tight constraints of mobile devices, why would we think that the team that created the most advanced smartphone/tablet processor couldn’t now design a 3GHz A10 machine optimized for “desktop-class” (a term used by Apple’s Phil Schiller when introducing the A7) applications?

If we follow this line of reasoning, the advantages of ARM-based processors vs. x86 devices become even more compelling: lower cost, better power dissipation, natural integration with the rest of the machine. For years, Intel has argued that its superior semiconductor design and manufacturing technology would eventually overcome the complexity downsides of the x86 architecture. But that “eventually” is getting a bit stale. Other than a few showcase design wins that have never amounted to much in the real world, x86 devices continue to lose to ARM-derived SoC (System On a Chip) designs.

The Mac business is “only” $20B a year, while iPhones and iPad generate more than 5 times that. Still, $20B isn’t chump change (HP’s Personal Systems Group generates about $30B in revenue), and unit sales are up 18% in last June’s numbers vs. a year ago. Actually, Mac revenue ($5.5B) approaches the iPad’s flagging sales ($5.9B). Today, a 11” MacBook Air costs $899 while a 128Gb iPad Air goes for $799. What would happen to the cost, battery life, and size of an A10-powered MacBook Air? And so on for the rest of the Mac line.

By moving to ARM, Apple could continue to increase its PC market share and scoop much of the profits — it currently rakes in about half of the money made by PC makers. And it could do this while catering to its customers in the Affordable Luxury segment who like owning both an iPad and a Mac.

While this is entirely speculative, I wonder what Intel’s leadership thinks when contemplating a future where their most profitable PC maker goes native.

— JLG@mondaynote.com

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Postscript: The masthead on Matt Richman’s blog tells us that he’s now an intern at Intel. After reading several of his posts questioning the company’s future, I can’t help but salute Intel management’s open mind and interest in tightly reasoned external viewpoints.

And if it surprises you that Richman is a “mere” intern, be aware that he was all of 16-years-old when he wrote the Apple and ARM post. Since then, his blog has treated us to an admirable series of articles on Intel, Samsung, Blackberry, Apple, Washington nonsense — and a nice Thank You to his parents.