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New PowerPC design unveiled

Motorola's AltiVec technology is taking the chip architecture in new directions.

3 min read
Motorola unveiled a new technology for boosting the performance of PowerPC chips, taking the venerable chip architecture in new directions.

As reported yesterday, the Schaumburg, Illinois-based company added what is partly an answer to Intel's much-hyped MMX multimedia instruction set. The "AltiVec" technology will be incorporated in some commercial PowerPC chips starting in late 1998, according to the company.

But the technology also goes far beyond MMX, addressing a range of markets that MMX doesn't such as networking and telephony. Interestingly, the chip is being rolled out at Networld+Interop which is primarily a networking conference.

AltiVec adds fatter pipes and a "data engine" inside the chip for manipulating large quantities of data. Potential applications include speech processing and networking routers, which manage Internet traffic.

"This is really a big ray of hope for the PowerPC people. The perception is that the PowerPC is fading with the Mac, and that their number is up, but that's not really case," said Jim Turley, senior analyst with MicroDesign Resources. "They are succeeding, but not in the glamorous, high profile places people hear about," he added.

Apple Computer, which took part in the development of the technology, is expected by analysts to eventually use the new technology in its Macintosh computers to aid in image and video processing. Apple could detail its use of the technology as soon as its developer conference later this month.

Apple could not be reached for comment.

Other chips such as Sun Microsystems' Sparc and Digital's Alpha already have similar technologies, analysts note. Intel's MMX technology is perhaps the most widely known because of that company's marketing efforts.

"AltiVec can gobble a lot more data at a time than any others," Turley said, comparing its potential favorably with Intel's MMX. "Particularly crippled is MMX because they grafted [multimedia extensions] onto a processor never meant for it."

AltiVec is two new technologies, one hardware, the other software. On the hardware side, it adds a new "execution unit" inside the PowerPC processor that is built to efficiently process certain kinds of data. All mainstream processors already come with execution units call "integer" and "floating point" designed to efficiently process other kinds of data.

The new "vector unit" operates concurrently with the existing floating point and integer units found in typical desktop PC processors.

On the software side, the chip will be able to use a total of 162 new instructions for manipulating data. This is of critical importance but with one major catch: Developers must write programs that use the instructions, and changes need to be made to the operating system to accommodate the instructions, said Turley.

In stark technical terms, PowerPC chips with this technology will be able to process 16 times the number of data "chunks" for each clock cycle compared to previous designs.

"Think of the chip as having a doorway in and out of the chip that's 32 bits wide, but the hallways are 128 bits wide," Turley offers. "Once data is moved out of [main memory] and into the chip, they can really swing lots of data around and do special number crunching, more so than other chips."

For instance, a single chip with AltiVec technology could run 30 28.8-kbps modems in a remote access server (the kind a Internet service provider uses). This compares to a high-performance digital signal processor (DSP), which can run 8 modems, says Will Swearingen, product marketing manager for Motorola.

Motorola said the chip will initially be targeted at high-end networking and desktop computing applications, but will later find its way into lower-cost designs. The chip will be produced in sample quantities during the second half of 1998, with volume production slated for the first half of 1999.