Which will prevail on PCs: x86 or ARM?

One possible side-effect of the Mac Intel to Apple Silicon is that WinTel PCs will also switch to ARM in the not-so-distant future. I want to spend a bit of time thinking about this.

Can Microsoft (or any other company) build a translation layer like Rosetta 2?

On the Vergecast, Walt Mossberg commented;

But the thing that really impresses me is their translation layer. This thing called Rosetta 2. They had a Rosetta when they made another processor change some years ago. And what it does is it takes apps that have not been written for this processor that were written for the Intel — which is most of the third-party apps so far — and it runs them. And I got to tell you, they run fast. They run normally. I mean, fast. If you were doing a blind test and you didn’t know this was originally written for Intel, still written for Intel, and it was running through this Rosetta thing, you would never know it. At least that’s been my experience. I don’t know if it’s been yours.

Indeed, as I have noted, benchmarks show that Intel code translated with Rosetta 2 achieves 78-79% of the performance of native code, which is an enormous leap forward compared to the Intel emulator that is on Windows for ARM.

This suggests that Microsoft is far, far behind today, and that it will take a large engineering effort to develop a Rosetta 2 equivalent.

Is there an inherent advantage in the ARM architecture that enables the performance in the Apple M1? Will any ARM silicon designed for PCs deliver similar speed?

Apple has shown that it is possible to develop an ARM instruction set based silicon that delivers great performance for desktop-style applications, whilst providing much superior battery-life.

One question is, does this mean that if Qualcomm or other ARM vendors create designs tailored to PCs, we will see the same kind of improvement? Is there a secret Apple sauce that is hard to imitate, or can other companies do the same? The second question is, does the ARM architecture itself have an inherent advantage, like, for example, RISC vs. CISC?

First of all, we know that Apple silicon for smartphones already significantly exceeded those from Qualcomm, Huawei, MediaTek and Samsung (Geekbench 1, 2). In single-core, the difference is almost two-fold. Therefore, we can safely conclude that Apple has had a secret sauce for many years.

Second, regarding any inherent advantages that the ARM architecture may have had over Intel x86. The consensus seems to be that although ARM had advantages for mobile usage in 1990, since then, due to the sheer increase in transistors per chip, the advantages today are mostly negligible (Quora 1, 2, 3). Apparently, the differences between ARM and x86 are due to whichever is the de facto standard in mobile or desktop, and access to the best manufacturing technology. The conclusion here is that ARM does not have an inherent advantage neither in battery-life nor performance, RISC vs. CISC notwithstanding.

If this is the case, then the real reason why Apple was able to get extremely good performance out of the ARM architecture is almost exclusively due to Apple’s secret sauce. Unified memory is obviously part of this, but there may still be other significant improvements.

It looks like, here again, a significant investment in time and resources will be necessary until we see similarly performing silicon from non-Apple sources.


On the software side, Microsoft will need to invest significant resources to improve their Intel on ARM emulator. What they currently have is very far behind. An alternative to this is for Windows application software vendors to diligently modify their software to run natively on ARM — Good luck with that.

On the hardware side, ARM silicon vendors will need to invest large efforts to design features on top of the basic ARM architecture.

Making both of these things happen is not going to be easy. 

The last time Apple made such a big leap was when they announced the iPhone, and that took about 4 years for Google to catch up with (Ice Cream Sandwich in 2011 is, in my opinion, the first time that they came anywhere close to iOS). This was mainly a software-only catch-up because at that time, Apple had just started using their own silicon (the A5) in the iPhone 4s, and hence CPU performance was similar to what you could elsewhere. It was totally up to Google alone to deliver.

This time, we need significant investments from both software and hardware, and no company owns both sides of the coin. Unless they see a future with a significant share of ARM-based PCs, application developers will not modify their apps. Microsoft will not develop a great emulator/translator unless silicon vendors can promise great performance. Silicon vendors won’t develop their own designs unless Microsoft makes a great emulator. Consumers won’t buy until they can run their apps with good performance. We are seeing a chicken and egg problem here, and this is because of how the non-Apple value-chain is divided. This is what has plagued Microsoft’s ARM efforts so far and even with the announcement of Apple’s M1, I don’t see this moving forward. Indeed, we have seen a similar picture with Android smartwatches.

Given this market dynamic, a much more feasible scenario is that Intel will fix their process woes and develop a great x86 mobile chip by today’s standards at 7nm or similar. ARM from other vendors won’t push x86 out of the market and may well be stuck in the same state as today. No revolution — just evolution. Apple will not come after the server market, the corporate PC market, the gaming PC market, nor the low-end market. Macs will gain some market share, but the damage will be restricted to the limited markets where it competes. Intel should focus on creating better chips than AMD and shouldn’t be distracted by Apple’s M1.

The Itanium fiasco provides us with a good idea of how things will work out here. With a segmented value-chain, there is a huge inertia toward sustaining evolution and that’s probably what we’ll see here.

My conclusion. It seems that despite its recent failures, market dynamics still strongly favour Intel and it will end up being on the winning side this time.


Update 2-Dec 2020

A story appeared on PC World noting the absence of any mention of Qualcomm chips that can compete with Apple M1 during the Snapdragon Tech Summit.

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