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May 2011

Shootout on the Oak Trail

COLIN MCCRACKEN & PAUL ROSENFELD

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Hollywood has done and overdone its share of old west shootout films, from Clint’s flicks to the Chisholm Trail to the star-studded big budget blockbuster Silverado Trail. Setting its sights on the modest embedded market, Intel’s market machine has entered Oak Trail for an SFF shootout. Incumbent sheriff ARM with its posse of ASIC and standard chip manufacturers lie in low power wait states for the would-be x86 contender to mosey into town.

We reported in this column several years ago that x86 and RISC processors inhabit distinct territories, with customers squarely in one camp or the other, since the price/performance/power profiles didn’t overlap. With shrinking transistors, both sides are closing in on each other, x86 from above and ARM from below, while competing for the coveted smart phone and tablet PC frontier. 2011 promises to bring an epic duel due to multicore ARM Cortex-based chips with integrated GPUs. Of course, some chips will be “gone with the wind” as the consumer market churns, while others just might loiter around for the minimum 5-7 year lifecycles the embedded market requires.

The Intel Developer Forum (IDF) in China was chosen as the primary launch event for the “Oak Trail” platform. You know that you are at an IDF keynote when you see the Intel speaker talk about smart phones while being recorded by dozens of ARM-powered smart phones in the audience, and you wonder whether that is as close as Intel will ever get to being inside a smart phone. 10” tablet PCs, however, are still well within the mainstream Windows 7 + x86 platform as proven by Intel’s tablet design wins.

Oak Trail, available first in tablets this summer and subsequently for embedded lifecycles as well, has accomplished some notable milestones as the latest Z-series Atom platform. At 3.0 watts thermal design power (TDP), the “Lincroft” code name processors—1.5 GHz Atom Z670 and 1.2 GHz Atom Z650—have reached a new low TDP among Gigahertz x86 mobile and ultra-mobile processor families with integrated graphics. 

The companion chip / chipset called the SM35 Express chipset (“Whitney Point”) is rated for 0.75 watt TDP. Systems should be designed to cool the 3.75 watt platform TDP, although the typical tablet use case may draw no more than 1 watt, pushing battery life up to cover an 8-10 hour shift for medical and warehouse workers, for example. This is well below the 5W Queens Bay platform (Atom E620-E680 series), although depending on I/O and expansion requirements, the Tunnel Creek (E6xx) processor can run without the Topcliff I/O hub to get down to three and a half watts.

Although the power consumption is still high by single-chip RISC standards, Intel has done something with the SM35 Express chipset that deserves high honors. The unprecedented low 0.75W TDP directly results from self-restraint on the I/O side: SM35 Express contains only USB client ports, the LPC Bus, SPI, I2C, SDIO ports and a SATA port (LVDS comes from the processor). We’ve been so conditioned to super-sized PCIe lanes, USB 2.0 and 3.0 ports, Gigabit Ethernet MACs and SATA gen 2 and 3 assault rifle expansion interfaces and the expensive FPGAs with SERDES PHYs for bridging down to low-speed peripherals, that we’ve lost sight of an easier, greener weapon. Medical tablets, inventory logistics computers, and even remote self-powered sensors can attach A/D converters, 3-axis accelerometers, temperature sensors, actuators, transducers, serial ports, GPS receivers and other low-speed peripherals using appropriate low-speed buses. This is the way that ARM-based ASICs and SoCs have done it for years, and Intel finally got it right. Unfortunately, this low-power platform might not attract most of the off-the-shelf computer board vendors who won’t appreciate the value of these low-speed expansion interfaces. And we’re still trying to explain the reason for “Express” in the chipset name.

Other x86 manufacturers are digging deeply into their tool chests, largely around graphics processing such as AMD’s Fusion, VIA’s Nano and DMP Electronics’ Vortex86 families, to find their embedded niches. But the shootout on the Oak Trail features Intel against the ARM posse—NVIDIA, TI, Qualcomm, Freescale, Broadcom, Marvell and others. Gentlemen, take your 20 paces…