PowerPC's Future Looks Bright

Long time rivals on the microchip playing field, IBM and Intel, are at it again--this time in a competition to see who will emerge as victor in the 64-bit game. But what does this mean for the AS/400 community?

Picture yourself at the Microprocessor Forum, a convocation of semiconductor manufacturers that meets annually during early October in San Jose, Calif. It is here that the latest innovations in semiconductor manufacturing are discussed, where visionaries offer a glimpse into the future of microprocessor technology and where leading chip manufacturers are likely to make some of their biggest announcements.

It was at this event this year that IBM unveiled the design specifications for its next-generation PowerPC microprocessor--dubbed the "Power4." With its new Power4 64-bit processor, which features a unique dual-core, copper-based design, Big Blue seems poised to give Intel Corporation's Itanium a run for its money. (Formerly code-named "Merced," Itanium is Intel's several-years-in-the-making 64-bit microprocessor development initiative.)

The Power4 is initially slated to run at one GHz, will leverage IBM's .18 micron copper technology and is based on a design that leverages two processor cores on a single die. According to IBM, each processor will share more than 100GB/s of memory bandwidth with an on-die L2 cache.

Power4 processors can be combined in multichip modules of up to four dies, and IBM has developed a new I/O technology--dubbed synchronous-wave interconnect--that connects the four dies at bus speeds in excess of 500 MHz.

"You've got two processors on a chip, you've got four chips on a multichip module, so on a little 4x4 [form-factor] you've got eight one GHz CPUs, which is pretty impressive," says Nathan Brookwood, a principal analyst with microprocessor research firm Insight64 (Saratoga, Calif.).

Most importantly though, say analysts, IBM will be able to deploy the Power4 across the entire range of its product line, from low-end RS/6000-based workstations to high-end System 390 mainframes, AS/400 hosts and RS/6000 servers.

An Itanium-based AS/400?
What is surprising, then, is talk that suggests Itanium might be used in place of Power4 on both IBM's AS/400 and RS/6000 platforms. Ironically, a report appeared within days of IBM's sensational technical briefing in San Jose that seemed to place the future of OS/400 on the PowerPC in jeopardy. In early October, a leading IT publication quoted Intel's director of Itanium marketing Ron Curry as saying that Big Blue was contemplating a switch from PowerPC to Itanium on future versions of the AS/400.

Brookwood admits that he was puzzled by the OS/400-on-Itanium report when he first read it. According to Brookwood, the roadmap that IBM outlined for the Power4 processor at the Microprocessor Forum points to a common PowerPC base for both of Big Blue's midrange computing platforms, the RS/6000 and the AS/400.

"Clearly if you look at what they've said about Power4, it's designed to be the underlying hardware for both the future AS/400 and RS/6000 lines," Brookwood comments. "Given what [IBM's] doing with Power4 and its desire to converge its RS64-3 and Power3 products into a common product with Power4, there's absolutely no reason for them to want to do that on an Itanium-based hardware configuration."

And then there's the question of performance. When it ships, Itanium is expected to be significantly more powerful than microprocessors from rivals Compaq Computer Corp. and Sun Microsystems Inc., among others. But Insight64's Brookwood says that the Power4 plans outlined by IBM at the Microprocessor Forum suggest an architecture that could potentially eclipse Itanium itself.

"That thing is going to probably have more raw cycles than an Itanium chip," Brookwood contends. "Even a single Power4 chip running two processors at one GHz is conceptually far more powerful than an [equivalent speed] Itanium."

PowerPC Strategies
IBM has long employed a dual-purpose PowerPC development effort for both the RS/6000 and the AS/400. The AS/400, for example, currently leverages the PowerPC A50, known in industry circles as the "Northstar" microprocessor. Northstar implements special PowerPC extensions for the AS/400--dubbed Power PC AS--at the level of the processor core. RS/6000 systems also use a PowerPC processor based on the same design as that of the Northstar, but with different core architecture extensions, which is dubbed the RS64-II.

If anywhere, some analysts say, it's in the area of RS/6000 support that IBM's intentions may be most questionable. Big Blue is partnering with Unix vendor the Santa Cruz Operation Inc. (Santa Cruz, CA) to develop the "Monterey Project," an effort to create an enterprise-class Unix operating system for the Itanium processor based on both the Santa Cruz Operation's SCO Unix and IBM's own AIX.

"IBM often makes decisions these days based less on technologies that they own and more on the competitive nature of the market and how much they can reduce the cost of a product," asserts Rob Enderle, veteran Intel-watcher and a senior analyst with consultancy Giga Information Group (Cambridge, Mass.). "If it meets its design expectations, Itanium will almost certainly be a higher volume product [than Power4], which will mean it has a lower acquisition cost, which might mean that IBM could replace the PowerPC in their RS/6000 boxes."

The Path to the Power4
But with the impending introduction of IBM's I-Star processor, the PowerPC's future on the AS/400, at least, appears assured. I-Star is expected to deliver numerous performance enhancements over Northstar--including a purported doubling of performance--I-Star will offer a clear path to Power4.

Analysts also speculate that the Itanium could finally end up on the AS/400 in a role similar to that of Intel's existing Pentium Pro and Pentium II microprocessors: as an Integrated PC Server (IPCS). IBM initially unveiled an IPCS based on Intel's Pentium Pro 200 and currently offers the Integrated Netfinity Server option for the AS/400, which features a 333-MHz Pentium II microprocessor.

As far as Giga's Enderle is concerned, however, existing OS/400 users wouldn't have much to worry about even if IBM made the switch wholly to Itanium on the AS/400.

"IBM has a very liberal end-of-life strategy, so even if they were to abandon the [AS/400's existing] processor-base, it's extremely unlikely that they would drop support for [existing AS/400s]," Enderle comments. "Given the movement of technology, that's probably one of the few safe bets in today's market."

Itanium is expected to debut sometime in mid- to late-2000. The Power4 is scheduled to ship sometime in the second half of 2001.

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