How will Microsoft’s Arm-based projects compare to Apple’s?

Article By : Brian Dipert

A look at the Surface Pro X provides an opportunity to compare Apple and Microsoft's Windows Arm-based projects.

What I’m about to say may shock those of you who’ve read my stuff before and are therefore already well aware of my longstanding love affair with all things tech; I returned a Christmas present the other day (don’t worry, I’ve already determined how to otherwise spend the funds). I’ll give you a minute to pick yourselves up off the floor.

Here’s the background: Within my mid-November coverage of Apple’s first systems based on the new Arm-based M1 SoC, derived from but not identical to the A14, I wrote:

I’m sure I’ll have more to say about Apple’s current status and future outlook in upcoming blog posts, along with the similar situation that Microsoft is experiencing with its Arm-based Surface Pro X product line.

The Surface Pro X is the focus of this particular post. Here’s a selection of stock photos of it in its Matte Black color scheme (a Platinum option is now also offered), both standalone and accompanied by its optional keyboard and pen accessories:

PR photo of the Microsoft Surface Pro X using its stand

PR photo of the back of the Microsoft Surface Pro X using its stand

PR photo of the side of the Microsoft Surface Pro X using its stand

PR photo of the Microsoft Surface Pro X with keyboard accessory

PR photo of the Microsoft Surface Pro X with its pen accessory

PR photo of the side of the Microsoft Surface Pro X using its stand and keyboardSource: Microsoft

As I’ve written about before, referencing both the 4th and 5th (2017) editions, I’ve got a fair bit of recent experience with modern Microsoft Surface Pro models built using Intel x86 processors. And my Surface familiarity actually stretches back to early 2014, when I picked up both Arm-based (Surface RT) and x86-based (first-generation Surface Pro) devices for evaluation and (in the latter case, at least) ongoing use. The Arm-based Surface RT device was my teardown victim back in November, in fact.

Reviews of the first-generation Surface Pro X (introduced in October 2019) and second-generation tweak (unveiled one year later) praise its thin-and-light form factor, its thin-bezel sharp display, and its speedy performance on Arm-native code. But that’s pretty much where the kudos end. Pricing is quite high; 8 GByte system memory-equipped first-generation models begin at $999.99, with a $500 (!!!) adder for an additional 8 GBytes of RAM. And no, the equally-pricey keyboard and pen aren’t included, either. The Arm-native code suite is to this day essentially restricted to Microsoft’s own Chrome-based Edge browser and Office suite. And 32-bit x86 applications run via built-in O/S emulation (for which 16 GBytes of RAM will likely be helpful), albeit with requisite performance and power consumption (i.e., battery life) impacts.

Unfortunately, subsequent to the Windows 10 announcement in mid-2015, a notable percentage of x86 applications have migrated to 64-bit versions, for which 32-bit-only emulation won’t suffice. Still, Microsoft announced at the end of September that emulation of 64-bit applications would appear in no later than two months. And I found a claimed “like new” system, at a historically-reputable online retailer, for a notable discount from the brand-new price. So I asked my wife to get it for me for Christmas, and she generously obliged.

November came and went without a 64-bit emulation release, alas. It did show up two weeks later, but its application compatibility is reportedly underwhelming (I’m being charitable with my wording) and more generally, operating system iterations have even backstepped on prior 32-bit emulated app support. And did I mention that the online retailer neglected to mention that my “like new” system arrived absent an AC adapter? So we sent it back within the full-refund time period; to its credit, the retailer picked up the return-shipping tab, too.

The dearth of native Windows-on-Arm applications more than one year after the initial Surface Pro X platform release, particularly from third-party developers, is at least somewhat surprising to me, especially in contrast to Apple’s situation. Microsoft’s fundamental problem is two-fold:

  • Windows-on-Arm is an adjunct to the core Windows-on-x86 business, for Microsoft and third-party developers alike, and
  • Microsoft’s initial Windows RT effort pretty much fell flat on its face, putting a “taint” on subsequent Arm-based projects.

Compare this with Apple’s experience thus far. The company announced its move-to-Arm intentions in June, following up with first systems five months later. Apple’s own applications are already Arm-native, of course, but a raft of third-party developers (including Microsoft itself) have also already unveiled Arm-native software versions. And for lingering legacy x86-only code, Rosetta 2’s translation capabilities have proven to be even more robust (both compatibility- and performance-wise) than I’d prognosticated.

To that point, even after Microsoft’s 64-bit emulation software gets fixed, it and its Windows-on-Arm partners’ hardware will seemingly still be hampered. The various Surface Pro X models, for example, run on the SQ1 and speed-bumped SQ2 processors, which although claimed “custom” are, as far as I can tell, little more than relabeled Qualcomm 8cx SoCs (other Windows-on-Arm OEMs’ systems are also based on various Qualcomm ICs). The 8cx combines four high-performance Kryo 495 Gold (Cortex-A76) “big” cores running at up to 2.84 GHz, along with four low-power Kryo 495 Silver (Cortex-A55) “little” cores operating at up to 1.8 GHz.

This all sounds good until you learn that the Apple M1 SoC’s four high-performance cores clock at up to 3.2 GHz, with the four low-power cores at greater than 2 GHz. The internal cache sizes are also notably larger with the M1 versus the 8cx (and Intel x86, for that matter) counterpart. And there’s one further twist that hasn’t gotten much media notice (yet, at least). When running x86 code, the M1 switches to an optimized memory consistency model total store ordering mode. Reflective of the fundamental gap between the two processors, a “bare metal” virtualized version of Windows for Arm runs notably faster on Apple’s hardware than it does natively on Microsoft’s own.

Presumably in response, Microsoft is reportedly finally making use of the Arm architecture license it took more than a decade ago to develop more optimized Arm-based chips. That’ll take time to reach fruition, of course; Apple’s been rolling its own silicon since the A4 in 2010. And it’s not like Microsoft is particularly known (yet, at least) for its chip-design expertise.

That all said, I realize that I’m still doing a bit of an apples(pun intended)-to-oranges comparison here. Apple’s so-far announced M1-based systems, the revamped MacBook Air and MacBook Pro, are traditional notebook computer form factors, whereas the Surface Pro X is a touchscreen interface-augmented “hybrid” that can operate either as an iPad-reminiscent tablet or (by attaching the keyboard) as a laptop. The Surface Pro X, unlike either the MacBook Air or MacBook Pro, also has built-in LTE cellular data connectivity, but so too does my Surface Pro 5. At the end of the day, I wasn’t willing to wait around for a more robust native-plus-emulated future that may or may not end up coming to pass. So I sent the Surface Pro X back.

Thoughts on anything I’ve shared in this piece, readers? Sound off in the comments!

This article was originally published on EDN.

Brian Dipert is Editor-in-Chief of the Embedded Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.

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