At this year’s Intel Developer Forum in San Francisco, the company has announced the next iteration of its low-powered Atom processor family, codenamed Bay Trail. Among other improvements, the new chips include a ‘Burst Technology’ feature analogous to the ‘Turbo Mode’ found on Intel’s mainstream Core i5 and i7 CPUs.
The Bay Trail range is split into three categories:
|Z3600 series: dual-core, targets Android||Z3700 series: quad-core, targets Windows/Android|
|N2000 series: dual-core (N2805, N2810), quad-core (N2910)|
|N3000 series: quad-core|
|J1000 series: dual-core (J1750), quad-core (J1850)|
|J2000 series: quad-core (J2850)|
Bay Trail is built on Intel’s Silvermont microarchitecture, which uses a 22nm manufacturing process. Silvermont also underpins Intel’s Merrifield SoC, which is aimed at smartphones.
We were briefed by Intel’s Graham Tucker, technical manager for Australia/New Zealand, on Bay Trail-T, the Z3000 series of tablet-optimised processors.
The tablet market has thus far been dominated by ARM, which licenses the architecture used in everything from Apple’s ‘A’ processors in the iPad and iPhone, to NVIDIA’s Tegra line of mobility SoCs.
Intel’s Atom, the processor family behind the netbook revolution, has gained traction in the tablet space this year thanks to Windows 8-based tablets. Though the cut-down Windows RT is capable of running on ARM processors, the full-blown Windows 8 and ‘legacy’ Windows desktop applications rely on the traditional x86 instruction set utilised by Atom.
Intel claims up to 2x the CPU performance, and 3x the GPU performance, of the previous generation of Atom SoCs. It also adds support for display resolutions up to 2560 x 1600, though only on models with dual-channel memory support.
Bay Trail represents two significant firsts for the Atom range: Intel’s ‘Burst Technology’ and the availability of quad-core models (4 cores/4 threads).
Burst TechnologyBurst Technology is analogous to the Turbo Mode used on Intel’s Core i3 and i5 notebook/desktop CPUs, which allows cores to run above their base frequency when there’s thermal margin available to do so.
Burst Technology is valuable in single-threaded tasks, as it allows multi-core processors to power down unused cores and dedicate the thermal and power savings to boosting the performance of the cores that are in use.
Tucker contrasted this to the big/little architecture used in newer ARM designs – such as the ‘eight core’ processor found in LTE versions of Samsung’s Galaxy S4 smartphone. The ‘eight core’ figure actually refers to four ‘big’ (high power) and four ‘little’ (low power) cores, which operate in big/little pairs. One or the other core in each pair can be in use at a time, depending on the processing load of the phone. This allows for power savings via the ‘little’ cores, and a rapid switch to high performance by spinning up the ‘big’ cores.
Tucker claimed that with its 22nm process and innovations such as Burst Technology, Intel needn’t use such an architecture to deliver a dynamic balance between low power usage and high performance.
Burst Technology balances power not only between cores, but between other packages on the SoC such as graphics, display and camera image processing. For instance, whilst running a graphically-intensive single-threaded application such as a game, the headroom provided by the unused cores and powered-down camera would be diverted to the loaded core and graphics block.
Intel HD GraphicsIntel has also brought its HD Graphics engine to the Atom platform, reflecting a cut-down version of the onboard graphics from the Core i range.
The new graphics architecture for Atom has support for DirectX 11 and OpenGL ES 3.0, and provides support for display up to 2560x1600 pixels in size on SoCs with dual-channel memory support. Models with single-channel memory are limited to 1920x1200, or in the case of the lowest-end Z3680, 1280x800.
The platform has 4 execution units, at a maximum clock speed of 667MHz including Intel’s Boost Technology. It provides full hardware acceleration for H.264 video encoding.
Atom has traditionally been weak in the graphical stakes, both in its application support and performance. With mobile gaming a commonplace use of consumer tablets, this is certainly a weakness in the Intel-powered tablet space. The improvements here may provide Intel with an edge in this area, and could potentially improve the consumer appeal of Windows-powered tablets should game developers target the platform as they have with iOS and Android-based devices.
Bay Trail-T product family
|Number of cores||4||2|
|Frequency||Up to ~2.4GHz||Up to ~1.8Ghz||Up to ~2.0GHz|
|Peak memory bandwidth||17.1GB/s||10.6GB/s||17.1GB/s||10.6GB/s||8.5GB/s||10.6GB/s|
|Memory capacity||4GB max||2GB only||4GB max||2GB only||1GB only||2GB only|
|Max display resolution||2560x1600||1920x1200||2650x1600||1920x1200||1280x800||1920x1200|