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Intel i855GME to pave way for ‘Centrino 2’ next year

Update Dothan, Sonoma, Alviso and Azalia details

IDF Intel today added a second chipset to its Centrino mobile platform even as it offered more details of the next-generation of Centrino, codenamed 'Sonoma', at Intel Developer Forum.

Based around the 90nm 'Dothan' Pentium M chip, Sonoma includes the 'Alviso' chipset and Calexico 2 Wi-Fi adaptor.

Dothan, demonstrated by Anand Chandrasekher, VP and General Mananager of Intel's Mobile Prods Group, is clock-for-clock significantly faster than today's Pentium M. Chandrasekher revealed for the first time that Dothan contains 140 million transistors - more than the 125 million in Intel's upcoming 'Prescott' desktop CPU, primarily because of the large 2MB L2 cache.

Indeed, the cache takes up more die real estate than the processing core.

Dothan also features more efficient register management than first-generation Pentium Ms provide, and an enhanced data prefetcher to guess what data and instructions are most likely to be needed and push them ahead of time into all that L2 cache.

Alviso's North Bridge features a new graphics core - though external accelerators can be added via the PCI Express bus - but more importantly adds dynamic screen power-saving technology, which controls a notebook's backlight on the fly to reduce the backlight brightness - and thus its power consumption - based on what's displayed on the screen. Intel claims its Display Power Saving Technology (DPST) can cut screen power from Centrino's 5W to an average of 3W. Expect a 25 per cent overall power reduction, said Chandrasekher.

The North Bridge also supports DDR 2 SDRAM, Intel said, chosen for its superior power characteristics.

The Alviso South Bridge, ICH6-M, brings Serial ATA and Gigabit Ethernet to Centrino. The chipset uses the ExpressCard add-in format, and presumably its miniPCI equivalent, which is how Calexico 2 will be connected to the system. The Wi-Fi component is likely to support 802.11a, b and g, and will offer 802.11i (AES) and ccx security.

ICH6-M also features 'Azalia', a sound system that supersedes AC97. In addition to Dolby 7.1 support, Azalia knowns about CPU power management modes, unlike AC97, which has no support for such technology. Again, says Chandrasekher, that will lead to further improvements in battery life.

Sonoma will ship in the second half of next year, suggesting it will appear after Dothan itself ships. The processor is scheduled for 'revenue shipments' in Q4, in time for product shipments early next year.

In the meantime it will probably be implemented with the new i855GME chipet. Pin-compatible with today's i855, the new version offers DPST and an improved graphics engine that can automatically adjust its clock frequency when switching between AC and battery power. Only two frequencies are supported, one for each power mode. On AC, the core is clocked to 250MHz, up from the i855GM's 200MHz. The new Centrino part also supports 333MHz DDR SDRAM, for the first time.

The i855GME is available from today, said Chandrasekher. ®

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