Nevertheless, a debate is heating up in some circles of the PC world about whether the venerable PC chipset will stay or fade away as process technology makes it increasingly feasible to bring its features on board the CPU.

The quick answer: it's not going anywhere anytime soon.

However, there will be certain device classes where it will make sense to merge the chipset and microprocessor, a process that is already partially underway at Advanced Micro Devices Inc. and Intel Corp.

"When it becomes a fixed-function device, and you know what the usage is, that's a perfect example to go ahead and integrate," said AMD's David Orton, executive vice president of its visual and media business and former CEO of ATI Technologies.

Some examples include the emerging class of ultra mobile PCs as well as simple thin-client PCs. The latter may be easier because it's a more established device class, while the former is still in flux and will likely require a host of wireless connectivity options that may make it tougher to pin down a static feature set.

Orton agreed that while UMPCs are a target, keeping the platform flexible in its early days will outweigh cost reductions achieved through using a monolithic piece of silicon.

Intel's Richard Malinowski, general manager of the chipset group, was more emphatic: "The kitchen sink, everything in one chip solution just doesn't work because of the integration problems," he said.

Nevertheless, one ardent believer in this approach is Via Technologies. Earlier this month it released its smallest motherboard yet, the mobile-ITX. Designed for future UMPCs, it's smaller than a business card and is built around a low-power 1.2GHz VIA C7-M processor that comes in a 9mm x 11mm package and an integrated north/south bridge measuring 21mm x 21mm.

"This is not where we stop. We believe in another year or two we will have something smaller — the CPU single chip will happen," said Via chief executive Chen Wen-chi.

Via CPU designer CJ Holthaus acknowledged that combining the CPU and chipset is the "holy grail" of what Via is trying to achieve. To do so, the company will have to overcome issues with aligning process technologies and a range of voltages.

For instance, south bridges will incorporate I/Os that could need 3.3-volt power supplies or 5-volt power supplies. Combining that with low voltages used on CPUs in portable devices would be challenging. Orton, however, believes chip designers have the experience to do it and could employ tools like on or off-board regulators to make adjustments.

In general, though, south bridges tend to be in made in process technologies one or two generations removed from the leading edge because of power needs linked to the I/O.

"Because it is I/O intensive, you could shrink it but you are still I/O bound so your die size wouldn't get any smaller," Orton added. "But if you have a very specific set of I/Os, which may only use up 40 or 50 pins, then that may be doable."

By: DocMemory
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