IBM confirms Altivecked POWER4-lite

Speeds and feeds

Microprocessor Forum IBM's Peter Sandon disclosed technical details for IBM's PowerPC 970 processor in San Jose this morning and confirmed that the processor supports the AltiVec instruction set. In addition to providing a competitive workstation and edge server chip for IBM - which deploys POWER3 in these space and power sensitive designs, the processor is tailor made for high end Apple machines. It's expected to sample in the first half of next year, and appear in production volumes in the second half.

970 is a single 64bit core - as opposed to today's POWER4 - with IBM predicting 937 SPECint2000 and 1051 SPECfp2000 at 1.8Ghz, and 5220 MIPS. Initial quantities will debut at 1.4 to 1.8Ghz, with 512kb of Level two cache. In his presentation, he described these as "conservative" estimates.

There are two SIMD execution units (IBM doesn't use the word 'Altivec' in the presentation); 9 fetch/decode stages and up to 8 issues per cycle.

32bit code runs natively on the 970, says Sandon. "There is no emulation," he explained. 32bit operating systems need to be modified but the list of modification is not large.

Power consumption is specified as 42W at 1.8Ghz (1.3v) and 19W at 1.2Ghz (1.1v). IBM says the processor has the same core voltage (1.3v) as the Motorola 7455 that forms the mainstay of Apple's desktop line.

Apple confounded expectations by opting to use higher frequency 7555 processors in its professional G4 tower machines this summer, instead of Motorola's 7470. With a year to go before Apple can use POWER4-lite, why even bother supporting its joint IBM-Motorola BookE-compliant sibling, G5?

Tom Halfhill of MDR, which is hosting the conference, said the 970 would still be slower than x86, but that performance should be better than clock speeds imply.

"Now that Apple has a real workstation-class and server-class OS, it needs a real workstation-class and server-class processor," he said.

The 970 smokes today's desktop competition in terms of raw number crunching. By way of contrast, AMD told us today that when Opteron debuts in the first half of next year it will ratchet up a SPECint of 1202 and a SPECfp of 1170. These, AMD's John Crank told us, were based on real silicon. Nothing stands still in this business. ®

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