For much of the past year we've been hearing that Intel's Atom for Windows 8 tablets is going to be the one to beat. Ivy Bridge (and later, Haswell) will exist at the high-end of the Windows 8 tablet space but if you want Intel's answer to ARM based Windows RT tablets it's going to come from the Atom lineup. It's still too early to talk about pricing, but expect Atom based Windows 8 tablets to exist in the sub-$600 space. Exactly how low they go will depend entirely on what the OEMs decide to ship at. My hope is for prices to start around $399 rather than much higher but we'll see just how seriously the Windows 8 OEMs are going to take this launch.

Intel's Atom for Windows 8 tablets has gone under the codename Clovertrail for quite some time. Today it gets official: the first Clovertrail SoC is Intel's Atom Z2760. Following similar naming to Medfield's Atom Z2460, there's a lot more that's shared between Clovertrail and its smartphone counterpart.

Similar to its approach with Medfield, Intel built a Windows 8/Clovertrail form factor reference design. The 8mm thick 10.1-inch tablet was built by a single ODM, but four manufacturers total are allowed to reuse those designs as they see fit. The FFRD approach isn't as necessary here as it was with Medfield because most of the traditional PC OEMs are already used to working with Intel. Given Intel's intense focus on driving platform power down however, building a reference design that others can follow makes a lot of sense. We'll actually see even more of this with Haswell next year.

From an availability standpoint we'll see the first Atom based Windows 8 tablets this fall. Intel announced design wins with Acer, ASUS, Dell, Fujitsu, HP, Lenovo, LG, Samsung and ZTE. The thinnest tablets will measure 8.5mm in thickness and weigh as little as 1.5 lbs. Not all Atom based Windows 8 tablets will be available on October 26th, but we'll see them starting a few weeks later.

Atom's big promise of course is ARM based tablet pricing with full x86 backwards compatibility, allowing the use of virtually all of your existing legacy Windows 7. It's a pretty compelling sell. If Intel can deliver the same (or better) performance/battery life compared to the ARM based Windows RT tablets, while preserving backwards compatibility Clovertrail would seem like a no-brainer. Simple solutions are rarely so simple, so we'll have to see this one play out in the market to be sure. Until then, we have some much needed architectural detail on Clovertrail and the Atom Z2760.

The Architecture

Medfield vs. Clovertrail
  Intel Atom Z2460 Intel Atom Z2760
Platform Codename Medfield Clovertrail
OS/Platform Target Android Smartphones Windows 8 Tablets
Manufacturing Process 32nm SoC (P1269) 32nm SoC (P1269)
CPU Cores/Threads 1 / 2 2 / 4
CPU Clock up to 2.0GHz up to 1.8GHz
GPU PowerVR SGX 540 PowerVR SGX 545
GPU Clock 400MHz 533MHz
Memory Interface 2 x 32-bit LPDDR2 2 x 32-bit LPDDR2

Clovertrail is the platform name, the single-chip SoC is called Cloverview. The architecture is very similar to Medfield's Penwell SoC. The most obvious differences are in the CPU and GPU configuration. Cloverview features two 32nm Saltwell Atom cores instead of one in Medfield/Penwell. These two cores run at up to 1.8GHz, a slightly lower clock speed compared to the Penwell that ships in Motorola's RAZR i. Each core has its own private 512KB L2 cache.

The GPU is a PowerVR SGX 545 from Imagination Technologies, clocked at a very high 533MHz. Direct3D feature level 9_3 is officially supported. Intel claims that the GPU is fed by a better engine in Clovertrail/Cloverview than it is in Medfield, however any additional details were impossible to come by.

The memory controller remains a dual-channel LPDDR2-800 design. Most tablets will see two 1GB devices populating the channels. Package on package (PoP) stacks will be used for DRAM and SoC integration, similar to what you see in a smartphone.

The other changes are more subtle. Video encode/decode is handled by IP licensed from Imagination Technologies, however the encoder is newer than what was used in Medfield. Clovertrail uses the same Silicon Hive ISP from Medfield. It supports two cameras (2MP/8MP) and burst mode.

The platform supports true connected standby, meaning Intel's new S0ix sleep states (similar to what was announced in Haswell). I realized I haven't yet detailed what these mean yet but in short on DC power you can expect polling roughly every 30 seconds for new data (incoming emails, tweets, etc...) delivering an experience somewhat similar to a smartphone. Off-SoC device drivers need to support Windows 8 run time power management (RTPM) to support these new low power sleep states. Intel claims that in its lowest platform sleep state (S0i3) the SoC's power consumption is below 2mW.

Connected standby is only currently supported by 32-bit Windows 8, so although Clovertrail supports x86-64 the platform will launch as 32-bit only. There's no support for alternate OSes at this point.

The SoC doesn't support SATA, just eMMC like most other smartphone/tablet SoCs. This is a bit of a disappointment as most eMMC controllers are pretty bad, but Intel tells us they've been working to improve things with the controllers that are out there.

There's no USB 3.0 support, Clovertrail just supports two USB 2.0 ports (OTG + xHCI, although OTG isn't supported by Windows 8). OEMs can obviously integrate hubs in any docking stations they may build.

On Pricing and ARM

Intel claims that there's no reason that Atom based Windows 8 tablets, from a hardware bill of materials perspective, should be any more expensive than their ARM based counterparts. The important takeaway is that Intel is significantly reducing the price of the Atom Z2760 due to competitive pressure from ARM. Most ARM smartphone SoCs seem to be priced in the $15 - $30 range, and I'd expect the Z2760 to fall somewhere in that range. Intel has shipped cheap CPUs in the past, but I don't know that they've ever shipped something this cheap. ARM's impact on Intel is measurable, it is the new AMD.

On Performance and Power

Microsoft isn't allowing any hands on performance of Windows 8/RT tablets yet so we don't have any of our own performance data to share. Intel did share some SPEC CPU2000 data it ran on its own with competing platforms. The data below wasn't generated by us so take it with a gigantic grain of salt:

Intel Generated SPEC CPU2000 Comparison - Normalized to Snapdragon S4
  SPECint SPECint_rate
Qualcomm Snapdragon S4 (1.5GHz) 1.00 1.00
Dual-Core 40nm ARM Cortex A9 (1.8GHz) 1.14 1.14
NVIDIA Tegra 3 (1.3GHz) 0.86 1.25
Intel Atom Z2760 (1.8GHz) 1.20 1.54

Everything here is normalized to the performance of Qualcomm's Snapdragon S4 (dual-core Krait, 1.5GHz). Basically it shows a tangible advantage for Clovertrail. That's not too hard to believe given what we've seen in the phone space, although we'll have to wait and see once we get our hands on final hardware. Sunspider scores at or below 800ms should be possible as that's what we've seen on preproduction hardware already.

We've already established that Medfield is competitive from a power standpoint with ARM based SoCs. It doesn't offer the best power characteristics, but it's hardly the worst. Middle of the road is the best way to put it. We don't have (and aren't allowed to have) a Clovertrail based Windows 8 tablet yet, so we'll have to reserve full analysis until then. However, Intel did share some early data with us from its own testing that points to Clovertrail battery life being competitive with other platforms:

Intel Generated Power Consumption Comparison
  Idle (Screen On) Web Browsing HD Video Playback
ASUS Transformer Pad Infinity 2.7W 3.4W 3.1W
Apple iPad 2 2.5W 2.6W 2.5W
Apple iPad (2012) 4.3W 4.5W 5.9W
Intel Clovertrail FFRD 2.3W 2.8W 3.0W

Intel standardized on 200 nits for all of its battery life tests, however I wasn't allowed to study/mirror the workloads and test procedure. The data looks good for Intel. Clovertrail's power consumption appears to be lower than NVIDIA's Tegra 3 and a little worse than Apple's iPad 2. This all looks quite plausible, I'm curious to see how power consumption would compare in Intel's tests to Qualcomm's S4. We'll find out for ourselves in due time.

Final Words

Intel was pretty light on Clovertrail details other than what we've published here. The real work begins once we start getting hardware late next month. The biggest question is really whether or not the OEMs will get pricing right for these tablets. An affordably priced Windows 8 tablet running Clovertrail can be very compelling for someone looking to carry a single device instead of a tablet + notebook. As with most things however, I am worried that we'll have to wait at least one more generation for perfection. I can't tell if I'm being cynical or realistic. Let's hope I'm surprised come October 26th.

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  • B3an - Friday, September 28, 2012 - link

    I'm sure it's just that particular benchmark. Maybe its why Intel decided to use that one, so it made them look much better (i'd still expect Clover Trail to be faster in other tests anyway, just not by as much). We all know that Krait is certainly more than 14% faster than A9 in most benchmarks, clock for clock.
  • Wilco1 - Friday, September 28, 2012 - link

    Why would you expect Clover Trail to be faster? Like Medfield it has a turbo but likely runs at 1.3GHz by default (possibly even lower if both cores are active). Therefore I wouldn't expect it to be much faster than Medfield, except for the slightly increased turbo speed or on multi-threaded tests.

    Note also that the real competition will be with quad-core Cortex-A15 (such as 1.8GHz Tegra4 due early next year) - not the older 40nm SoCs selected for benchmarking by Intel. Once the A15 is out, I wouldn't expect Clover Trail to win any benchmarks, not even SunSpider.
  • B3an - Friday, September 28, 2012 - link

    From what i've read Clover Trail's cores and platform seem to be a slight improvement over Medfield. And with a Turbo of 1.8GHz. i can imagine it being faster than competing ARM based Win RT tablets on release.

    I agree that when A15 is out it will be faster, but on the release of Win 8 i think Clover Trail has a good chance of being the fastest SoC in this power consumption category (for a short time).

    And a bit off topic but unless ARM can make *vastly* better SoC's i dont see any point in Win RT any more. A year ago i would argue that Win RT made perfect sense as Intel had nothing that came close to ARM for power consumption and battery life. But now that Intel can match ARM (or even just get close) and also getting in to form factors just as thin and light as ARM can while at the same price points, i dont see any point in Win RT at all now.

    Clover Trail Win 8 tablets will now offer literally everything that ARM Win RT tablets offer, but with the big advantage of running all desktop software. While A15 will be faster, it wont be massive jump, in REAL world usage i doubt anyone would notice a difference. It's not worth having another OS for ARM when it has no big advantage and will just confuse consumers and be a marketing nightmare.
  • Wilco1 - Friday, September 28, 2012 - link

    I agree Clover Trail is an improvement, but even at release it will be up against newer 1.7GHz quad-core Krait, 1.7GHz Tegra 3's and (if ready at launch) 2.0GHz OMAP5. With just dual cores and a far lower frequency (the turbo is only for short bursts), I do not see how Clover Trail could beat any of these.

    I can't see why you'd think Win RT is useless. Win RT devices will have much faster CPU/GPUs and better battery life, smaller form factors and lower prices. When Medfield came out we saw similar marketing from Intel how it was faster and lower power, but actual Medfield phones turned out to be mediocre in performance and battery life compared with phones based 40nm ARM SoCs - despite Medfield being 32nm (note Sunspider was the only benchmark that made Medfield look good, but that is mostly due to software optimization, not raw CPU performance).

    Yes Win RT can't run existing x86 applications directly. But is that really a big issue? Which x86 applications are you actually planning to run on your Win8 tablet? Will they work well on a low res touchscreen interface? I doubt it. Will they work well with power saving states? I doubt it. Important applications will be ported and adapted to tablets, just like Office and other basic Windows apps. At that point they should be available for both Win RT and Win8.

    However in the end I guess a lot of people will be persuaded by pricing, not the technical details.
  • Penti - Friday, September 28, 2012 - link

    Those new chips aren't out, and aren't powering Windows RT (WinRT is short for Windows Runtime which exists on both for confusion) next gen GPU's is still 6-12 months away for most users/devices.

    How about Office, Outlook? Business/Accounting software? Office 2013 RT won't be out the same time as these ARM-tablets. How about the fact that Windows RT is less capable then Android and alternatives? Price isn't everything here.

    Look the Surface RT will have a keyboard, it will have a multi-touchpad, it will have a touchscreen without pen-support (no dual-digitizer). x86 variants are just so much more attractive if you don't go with Android/iOS instead. It's not like it's easier to port apps to Windows Runtime then to Android NDK, iOS, and the competitors. SDK isn't even out yet in full for the platforms. When A15-based SoC's will be prevalent Intel will move on to Valleyview/Silvermont with none-Imgtec graphics thank god. Different devices and categories to begin with. Windows RT and Windows Phone 8 is quite limited in their platforms and supporting C#, C++, etc isn't winning over developers when every other platform is a lot more robust and still support all the technologies they would expect. Sure you will be able to do some DX stuff but Tegra 3 performs pretty badly. OpenGL ES reaches more users and developers have no reason to not target those if the engine of their choosing has support. Next to those devices (Windows RT) you would be able to pick up IvyBridge/Haswell tablets and they are easy enough to target for game dev.
  • Wilco1 - Sunday, September 30, 2012 - link

    The 1.7GHz Tegra3 is already out, for example HTC One X+ and Transformer Infinity use it. Faster Kraits are on the way, and Cortex-A15 will be released in the next few weeks. So it's not like Clover Trail will be competing with 6-12 months old SoCs, it will have to compete with the latest ARM cores from the very start.

    Office 2013 will be included in Windows RT from the start (it's called a preview as it's not the final version but 95% of functionality is there). IIRC Outlook won't be supported as RT already has an integrated mail program. Note that big business apps often support access via a browser, so in many cases you wouldn't need to install any software at all.

    You're right that x86 Win8 may be more capable, but you will be paying more as well (a lot more if the rumours are correct).
  • Penti - Monday, October 1, 2012 - link

    Tegra3 doesn't have an A15 or A15-class cpu neither does it have a next generation GPU so what are you on about? Tegra 3 is old. A clock increase doesn't change that. Kraits aren't using Adreno 320 yet. S4 Pro aren't available yet. LG Optimus G will become available with it pretty soon though. RT's Integrated mail application is worse than that built in into Android, iOS, Blackberry, Nokia etc. It's a lot worse then Android third party mail clients like TouchDown or iOS integrated. No Office 2013 RT aren't finished by October 26 it's coming next year for many. "Customers can expect to get these updates starting in early November through January depending on their language." - Office blog. Your right that a preview will be available when shipping though.

    Many large enterprise applications are accessible mainly through the web, but that doesn't cover all the large enterprises that for example uses Microsoft's technologies and business systems which runs as stand-alone app or all the small business apps you preferably run stand-alone. So it leaves out pretty much any business that doesn't afford a multi-million dollar ERP/CRM/Payroll system. It doesn't take into account that you can also run Citrix receiver to run those Windows stand-alone apps on an Android tablet just the same. Streamed apps probably works better on none-windows platforms here.

    On the other hand the preview of Office 2013 is available on Windows 8, 7, today, but not RT. Yet. Get some sense. Your off the target.

    Yes x86-tablets costs just the same as today. It's tablet pc's flying spaghetti damn it, about 800-1000 dollars. But that is for 600-800 gram devices, not second devices for none-existing entertainment. Later the slates will be able to go down to 600-700 dollar though i.e. same as higher-end Windows RT devices. Office 2013 RT home & student editions aren't something you your meant to run in business either for that matter. There is no reason the hardware in an CloverTrail Z2760 device should cost more then in an ARM equivalent either. For business it's all about the software, management and capabilities. While Office 2013 RT seems very powerful it's not a full replacement so alternatives still bode well. Of course 8 Pro devices has already licensed Office 2010 and productive environments to go from the start. In hybrid devices it shouldn't matter that 2013 preview has touch control-enhances. It's not like it's easier to port third party software to C++/CX/WRL then to any other platform. There is no definite advantage and it has to compete with much more powerful x86-devices that is only 150-200 dollar more or something of that character.
  • Wilco1 - Tuesday, October 2, 2012 - link

    The original point I responded to was: "And with a Turbo of 1.8GHz. i can imagine it [Clover Trail] being faster than competing ARM based Win RT tablets on release."

    My point is that it won't be faster as current ARM SoCs have much higher frequencies than the ones mentioned in the article.

    For example the latest Tegra3 has a 30% faster CPU and 25% faster GPU than the one benchmarked by Intel in the article. That means that even the old Tegra3 will outperform the Z2760 at launch.
  • B3an - Saturday, September 29, 2012 - link

    I guess we'll have to wait until Clover Trail tablets are available but the main advantage ARM/Win RT had was smaller and lighter form factors, and longer battery life. Being as Clover Trail will be in tablets that are just 8.5mm thick (shown off recently) it already matches ARM variants in that category. Then you have weight, which again it pretty much matches. Thats two main ARM/Win RT advantages already gone... Then you have battery life, and thats looking good but i'll wait for benchmarks. But lets say ARM tablets last an hour or so longer, even then Clover Trail will get "close enough". Say it gets 10 hours battery life and ARM gets 11.... just not worth going for ARM/Win RT with such a small difference.

    If theres a quad-core Krait out on release though, and has the Adreno 320 GPU, then that could actually make a noticeable difference in real world usage which is the only that that matters (99.9% of tablet users wont care about benchmarks). But that would be the on ONLY advantage Win RT tablets would have, and for how long? Before Clover Trail the choice was really simple: Intel + Win 8 for performance but bigger heavier designs with lower battery life and ARM + Win RT for slower but lighter and smaller designs with much longer battery life. Now that gap has become very blurred an it makes RT look quite pointless.
  • relic1138 - Tuesday, October 16, 2012 - link

    Right, why wouldn't a person just buy a full powered i5 - i7 laptop if he or she needs it. I never understood why people try to force their devices to work past the scope of it's design/purpose. Even running the none RT version on a i3 -i7 tablet sounds silly to me, Photoshop, have you seen those wonderful 24" Wacom monitors, silly.

    I do however like the detachable keyboard idea, I own a Asus Slider SL101 and I love using it to type out memo's, email's, doc's,ect.

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