Architectural improvements by both Intel and AMD will ensure we continue to see increasingly powerful devices, but without increasing costs
Intel’s Atom processors were always intended to expand the potential of compact, low-cost PCs, but it was only with 2012’s Clover Trail platform that the processor really began to deliver on its promise. Today, Clover Trail’s successor, Bay Trail, brings us fully capable laptops at remarkably low prices.
That’s thanks to the underlying Silvermont architecture, launched in 2013, which represents a few firsts for the Atom line-up. For a start, it’s the first Atom processor to embrace the 22nm 3D Tri-Gate technology introduced in Intel’s mainstream Core line with 2012’s Ivy Bridge processors. What’s more, it’s Intel’s first low-power SoC (system on a chip) to have out-of-order execution (OoOE).
Previously, Atom processors executed instructions in sequence from one long list, which meant that, say, execution resources could be left sitting idle while an instruction waited for the data it needed to complete. OoOE allows instructions to be fetched and executed out of order, so that as many resources are being used as much as possible. The result is a more efficient processor: Intel claims that Silvermont offers a 30% increase in performance over Atom’s last microarchitecture based on this one enhancement alone.
Add to this support for more instructions, including SSE4.1 and 4.2, POPCNT and AES-NI, and Silvermont is now roughly in line with where the Core architecture was in 2010; not bad for processors with a TDP that, in the tablet-focused Bay Trail-T line, can go as low as 2W.
It’s here that things become confusing. Where Siivermont’s predecessor, Bonnell, was used exclusively in Atom processors and SoCs, Silvermont has proved fast enough to be extended to Intel’s Celeron and Pentium lines. Buyers of low-cost laptops could be choosing between Bay Trail-T Atom-or Bay Trail-M Celeron-based laptops, unaware that they use the same core technology (albeit running at different speeds). What’s more, it means there are both low-power Silvermont and more performance-focused Haswell and Broadwell processors within the Celeron and Pentium lines - although these are differentiated by the sockets they support and the systems they’re designed to power.
Airmont takes wing
While it’s still the mainstay of low-cost, low-power PCs and tablets, Silvermont is due to be replaced very soon by an enhanced version - Airmont - which we should begin to see in new devices by the end of 2015, if not sooner.
Airmont sees Intel adopting the same “Tick-Tock” pattern with which we’re familiar from its full-power laptop and desktop processors - the “Tick” representing a die shrink of the process technology and the “Tock” representing a redesign of the microarchitecture. Airmont is effectively Silvermont shrunk to the same 14nm process used in Intel’s new Core M processors, allowing Intel to ramp up speeds without increasing power and thermal requirements, or to deliver the same speeds for a lower power consumption.
Interestingly, we’ll see Airmont in two formats: Cherry Trail, a SoC aimed at the tablet market, and Braswell, a derivative of Cherry Trail aimed at low-cost laptop and desktop PCs. What’s more, both SoCs will see a boost in graphics performance over the older Bay Trail-M and Bay Trail-T lines.
This should put the GPUs in the Atom and low-end Celeron processors on the same level as Ivy Bridge in 2012, while also adding support for DirectX 11.1, OpenGL 4.2 and OpenCL 1.2. In short, while you’re unlikely to be playing the latest Call of Duty on a low-end laptop, Cherry Trail and Braswell should have a modicum of GPU horsepower and be capable of handling older, less demanding 3D apps and games.
Braswell is the key processor line for laptops, and will probably see Celeron and Pentium branding, much like Bay Trail-M. It’s expected to use two to four Airmont cores combined with the eighth-generation graphics core, plus up to 2MB of L2 cache and a dual-channel DDR3 controller. And beyond? Well, challenges with the 14nm architecture and low-yield issues have seen Airmont processors pushed from Intel’s 2014 roadmap to this year, and its successor, Goidmont, delayed until 2016. Goidmont - the Tock to Airmont's Tick - should deliver a new microarchitecture and other enhancements, potentially bringing even more CPU and GPU performance within the same power range and at the same low price.
The AMD alternative
Unlike the tablet and smartphone market, the laptop market is one that Intel still dominates - but it doesn't have the field entirely to itself. AMD has its own E-Series line of APUs in this sector, and while they haven't been hugely successful, you’ll find the latest Beema dual-core SoCs in some budget models from Lenovo and Toshiba. Beema is based on AMD's Puma architecture - an enhanced version of the Jaguar architecture used in the Xbox One and PlayStation 4 games consoles - with OoOE and a Radeon R2, R3 or R6 GPU. These GPUs use the same Graphics Core Next (GCN) architecture as AMD’s mainstream graphics cards and APUs, albeit with a comparatively low 128 Radeon Cores, and a much lower GPU clock speed.
It’s expected to be replaced by Carrizo-L later this year, with up to four streamlined Puma+ cores, faster GCN 1.2 compute units and support for AMD's Mantle API and DirectX 12. While AMD is stuck with 29nm process technology at a time when Intel is moving down to 14nm. it hopes its architectural improvements will see Carrizo-L better equipped to take on Cherry Trail and Braswell processors.
Nvidia: ARM to the Max
Meanwhile, in the Chromebook and Android laptop market, Intel faces an unexpected rival: graphics giant Nvidia. Better known for 2013 tablets such as Google’s Nexus 9 and Nvidia’s Shield, the Tegra Ki processor has now crossed over into Acer and HPChromebooks, including the HP Chromebook 14 G3 and the Acer Chromebook 13.
Packing four ARM Cortex-A15 cores and a battery-saver core into a 28nm chip gives the K1 plenty of processing power, but with 192 Kepler GPU cores it’s the graphics performance where it really makes its presence felt. At the moment there are compatibility issues with some Chrome OS apps, particularly those using Google’s Native Client technology to run in the browser, but these may be overcome with time.
Nvidia has already announced its next-generation Tegra X1 processor, with four ARM Cortex-A57 cores and four ARM Cortex-A54 cores arranged in what ARM calls a big.LITTLE configuration, where the faster cores handle more demanding tasks and the smaller, more power-efficient cores swing into action for more basic or background tasks.
Again, though, graphics performance looks set to be the key differentiator, with the Xi packing in 256 of Nvidia's latest Maxwell cores, along with other GPU enhancements that make it roughly as powerful as a last-generation games console. That could make a new generation of Chromebooks even more compelling - providing there’s the software to make the most of all that power, which is by no means certain.
What the future holds
While high-performance processors aren’t going anywhere, in the next few years it’s likely to be the low-power, low-cost market where the real action takes place, as the lines between smartphone, tablet and laptop technology continue to blur.
That’s good news for everyone: having faster, more capable processors available at lower prices should make it easier for the big manufacturers to produce laptops and other devices that cut costs without cutting corners. And that means the budget laptops we’re seeing now shouldn't be a netbook-style flash in the pan.