Power.org Merges Power Instruction Sets, Gets New Members
August 7, 2006 Timothy Prickett Morgan
Having managed in February to get Freescale Semiconductor to join the Power.org community that IBM created to give others a voice in what happens with the Power chip architecture, the two companies have announced that they are now beginning the important work of creating a merged instruction set architecture, or ISA in chip geek speak, for Power that combines elements from IBM, Motorola, and other designs.
Way back in 1991, when the PowerPC Alliance got its start, IBM and Motorola (which spun out Freescale two years ago because it did not want to be in the server, desktop, or embedded Power chip business any more) did the silly thing and did not create a single, unified instruction set architecture for Power chips. There were 32-bit and 64-bit designs from both companies that had a lot of commonality and a high level of compatibility in some regards, to be sure. But some of the Power chip designs, such as the various Star family of 64-bit chips those that ended up in AS/400 and RS/6000 servers, had different memory addressing schemes and radically different properties from the PowerPC chips that ended up in Apple Mac PCs and Xserve server. While the gap in these designs was not as great as those that exist between Intel‘s Pentium/Xeon chips and its Itanium alternative, which has a radically different architecture, the differences were large enough among the Power and PowerPC chips to make it sometimes tough for software developers to create code that spanned these different chips. And for a long time, IBM and Motorola were content to keep it that way, because it meant Motorola and its OEM partners could not break into the clone IBM server business, and IBM had to use a different family of PowerPC chips (not its Star, Power4, or Power5) processors to sell against Motorola to chase Apple’s business.
Eighteen months ago, after Apple, the third of the original PowerPC Alliance partners, said it was dropping the Power chips from its machines, IBM decided it had better open up the Power architecture a bit and give it some breathing room, especially since people started questioning the viability of the Power processors even though IBM had managed to get two exotic variants of its into Microsoft, Sony, and Nintendo game consoles, and was working with Toshiba on consumer electronic devices powered by Power processors. (In the case of Sony and Toshiba, it is the “Cell” chip, and with Microsoft, it is the “Xenon” three core PowerPC variant.) In any event, as Apple relatively quickly and mostly painlessly moved to Intel’s new Core X64 processors–thanks in large part to the BSD Unix underpinnings in Mac OS X–IBM has been ramping up the marketing and technology machine for Power.org, and the proposal to merge the instruction sets of the various IBM and Freescale chips is one way to make it more likely that Power can extend itself into other devices.
IBM and Freescale run the Power Architecture Advisory Council, and sometime this quarter this council will release a new merged instruction set architecture, subbed Power ISA Version 2.03. This merged spec will include IBM’s virtualization extensions, Freescale’s AltiVec vector math extensions, variable length encoding, and other goodies. Power.org is also working on a Power Architecture Platform Reference specification aimed at helping companies create standard Power machines that run Linux. IBM also announced that it has added five more members to Power.org, bringing the total membership up to 40 companies.
While Power.org does not have a large direct effect on IBM’s server customers and their OS/400, AIX, and Linux platforms, the success of the organization–or its absence if IBM had not formed it–certainly does have an indirect effect. IBM and Freescale lost the Apple business, which was on the order of millions of chips, but IBM is selling tens of millions of chips for game consoles. Someone, sooner or later, is going to figure out that Power chips offer some benefits as Linux desktops and servers, and it will probably happen in the Asia/Pacific region first. Any way you look at it, the vastness of the embedded Power chip business makes it the only real credible non-compatible alternative to Intel’s Core chips, and that will remain the case so long as IBM and Freescale can keep companies embedding Power chips in all kinds of things. If that stops, then IBM’s high-end Power chip business–the one that does affect the System i5 and p5 servers–will come under pressure, and innovation could slow considerably. Neither IBM nor its customers want that to happen.