I did an article on ARM and x86 about a year ago, since multicore ARMs were up and coming, and Windows 8 would allow them to be used in netbooks, notebooks or even desktops, as competing solutions to x86. That was how I saw things at the time: ARM moving towards x86.
But Intel has recently introduced a new generation of Atom processors, codenamed Medfield. This is showing a move in the opposite direction: x86 moving towards tablets and smartphones. The move in itself is not new, as Intel has been trying to get Atom processors in embedded and mobile devices for a while now. But the difference is that Intel is actually succeeding this time.
As I mentioned last time, x86 bears some legacy which makes it inherently larger and more complex than a more modern architecture, such as ARM. However, this extra overhead is more or less a constant factor, where the rest of the CPU design will grow larger over time as more transistors can be fitted on a single die, because of manufacturing progress. For regular desktop, workstation and server systems, the x86 overhead has become a non-issue years ago. With the amount of execution units, caches and everything you find in a modern CPU, the legacy overhead of the x86 becomes insignificant. An added factor is that Intel has always had the most advanced manufacturing. This allowed them to fit more transistors in a smaller space, using less power, which could somewhat compensate for the extra cost of x86 legacy.
For Atom however, the small scale of things meant that Intel could not quite get the upper hand over the competition yet. An important issue with early Atoms was that it consisted of the CPU and a separate chipset, where the competing ARM solutions were a System-on-a-Chip (SoC). As a result, Atoms were not small and energy-efficient enough for mobile devices such as tablets, let alone smartphones.
Then Intel introduced Oak Trail, the first SoC version of Atom. This makes it more compact and more power-efficient. It was still too powerhungry for phones, but tablets were more or less within Intel’s reach now. But since ARM solutions still had better performance and battery life, Atom-powered tablets never took off.
The new Intel Medfield is an SoC as well, but it looks a lot better than Oak Trail. Oak Trail was built on a 45nm process, but Medfield uses a 32nm process. This puts Intel in its favourite position: a step ahead of the competition, who are still on 40nm process. The result is that x86 can now hide its legacy very well. And this time we will actually be seeing this Atom SoC in a number of tablets and smartphones.
So where I was expecting ARM to invade Intel’s turf, Intel is now doing the opposite. I was not expecting Intel to close the gap just yet. But it seems that they are well on their way. And 22nm is just around the corner for Intel, which may allow Atom to take yet another step forward compared to ARM.
This newfound competition is also interesting for ARM itself. Because Intel throws HyperThreading into the mix, which ARM does not have. And Intel’s SIMD extensions may also be slightly more mature than ARM’s. So we will have to see how ARM is going to respond to this.