There’s no power like low power

All modern PC notebook designs struggle with the weight, noise, heat, battery life, and performance issues of their earliest ancestors, and users’ expectations have advanced far faster than mobile technology. Intel kept shrinking its Pentium 4 desktops to mobile forms, trying to keep up, but that was a race it couldn’t win.

The Pentium 4 is Intel’s hottest desktop processor in more ways than one. Users were shocked to learn that Intel routinely ran its mobile processors at half their rated speed to reduce heat and extend the battery. They were equally unimpressed by news reports of super-fast PC notebooks leaving burns on users’ laps. Other notebooks made headlines with recalls of overburdened AC power adapters that would overheat and fail. They’d even catch fire, albeit rarely.

Remarkable as it seems, it wasn’t until early 2003 that Intel introduced a mobile chipset (CPU and supporting components) that was designed especially for mobile use. Before Centrino, all Intel-based notebooks were based on adaptations of chips designed for AC-powered desktop computers. This was a cost-effective way to meet users’ rapidly rising performance demands in the desktop and the mobile space at the same time.

Intel had a low-power processor technology, code-named Banias, in engineering for a while. But as long as the market accepted that good mobile performance meant dealing with machines that burned through pants and batteries, there was little pressure to hurry Banias’s debut.

The interloper

In 2002, the PC notebook market was shaken up by Apple’s PowerBook G4, a PowerPC-based notebook that struck an ideal balance between application performance and battery life. In fact, the PowerBook juggled these objectives so well that it left observers wondering how tiny Apple had managed what massive Intel could not. Instead of shrinking a desktop architecture down to fit a notebook, Apple engineered the PowerBook G4 from the ground up as a fast and energy-efficient mobile platform. And instead of ramping up the processor’s clock speed to boost performance, Apple extracted a bigger kick from adding a huge, 1MB, high-speed cache to a 1GHz RISC processor. The result was a sleek, six-pound portable with a large, bright display; incredibly fast graphics; impressive performance; integrated wireless networking; and a five-hour battery. Until the PowerBook G4 appeared, the market assumed that these attributes could not be combined in a battery-operated computer. It took Apple several years and a lot of customer-driven engineering to get it right. Owning the whole platform right down to the operating system gave Apple opportunities for optimization that few other vendors enjoy.

Once Apple had done the notebook the right way, PC customers started asking when it would be their turn. Even if Apple hadn’t come along with the PowerBook G4, customers would have grown tired of the trade-offs they have endured since the first PC portables emerged in the ’80s. The onus was on Intel to give its OEMs (such as Dell, Gateway, Toshiba, and IBM) the ability to create a PC notebook that would impose few, if any, compromises on its users.

Intel’s three-part answer

Intel’s solution has the potential to exceed the market’s expectations. Centrino’s marketing currently focuses on wireless networking. But this has far more to do with Intel’s investment in commercial Wi-Fi hotspots — sit in a Starbucks or the lobby of a Marriott and surf for $30 per month — than in any silicon wizardry. To qualify for the Centrino logo, a notebook has to implement Intel’s Pro/Wireless 2100 circuitry. But wireless is not integrated into the Pentium M CPU or the accompanying 855 chipset family. Pro/Wireless 2100 is a separate component set that OEMs can incorporate or swap out with other vendors’ wireless LAN technology.

Intel does 802.11b well, especially with regard to Windows system software. But the Centrino brand only covers 11Mbps 802.11b. Intel’s other wireless products support the 54Mbps 802.11a standard. Spurred on by Apple’s AirPort Extreme line and products from volume players such as Linksys (just acquired by Cisco), 802.11g is also rapidly gaining ground as a fast alternative to 802.11b. Centrino’s wireless component looks dated for having failed to support one of these two high-speed approaches. Several notebook vendors are opting out of Intel’s wireless solution even though that means sacrificing the super-marketed Centrino logo.

In addition to Pro/Wireless 2100, Intel requires either the 855PM or 855GM chipset for the Centrino logo. OEMs won’t be opting out of this component; it’s a perfect fit for the Pentium M processor. The 400MHz bus provides a desktop-speed channel between the processor and memory, graphics, and I/O. OEMs that put out smaller machines, including Tablet PCs and subnotebooks, will take advantage of the 855GM, which has an integrated display adapter. But most importantly, the 855 chipset can power down battery-hungry components when they’re not needed. That’s what suits it so well to the CPU element of the Centrino solution. What the Pentium M processor does with its time off is as important as how well it performs.

Performance and power-saving

Centrino’s Pentium M processor is based on a substantially improved Pentium III core. Unlike any Intel CPU before it, the Pentium M is capable of a variety of complex reduced-power states. During fluctuations in software’s demand for compute resources, Pentium M can ratchet its operating voltage and clock speed up and down over a series of steps. The CPU can also drift into one of several sleep states to further reduce power drain. While Intel carries the SpeedStep brand over from the Pentium 4M to the Pentium M, the implementation in Pentium M is more sophisticated.

Taking a tip from Apple, or possibly arriving at the same point while taking its own road, Intel turned the Pentium M’s top clock speed way down and ramped its cache size way up. The Gateway 450XL sent to us runs at a sensible 1.5GHz and has a 1MB cache. As have other reviewers who handled Centrino machines, I found that the 450XL feels faster, markedly faster, than any PC notebook I’ve used, even on battery power.

The 450XL seems to be goosing performance to keep graphical user interface updates snappy, then dropping back between activity bursts. This can’t be accomplished without tight operating system integration. Centrino critics point out that, so far, Intel has said nothing about making Centrino power management work under anything but Windows.

Intel’s Centrino mobile solution shows exceptional market adaptability for a company its size. This is a solution that can get smarter over time as operating systems, drivers, and OEM firmware learn to ply Centrino’s power-saving features. Testers are finding a wide variation in battery life from vendor to vendor, model to model as manufacturers adapt the platform.

Centrino, or the pieces of it that OEMs choose to implement without taking the logo, marks the end of a long dry spell in Intel mobile innovation. Finally there’s a mobile technology from Intel that makes it worth shopping for a new notebook.