June 8, 2005 4:00 AM PDT

The brains behind Apple's Rosetta: Transitive

A Silicon Valley start-up called Transitive is supplying Apple Computer with a crucial bridge to enable the move to Intel-based computers, but skeptics worry about performance problems that have plagued similar products.

Transitive is providing the engine used in Apple's Rosetta software, which translates software for its current machines using PowerPC processors so it can run on forthcoming Intel-based Macintoshes. "We've had a long-term relationship with them," Transitive Chief Executive Bob Wiederhold said Tuesday.

As a program runs, Rosetta translates its PowerPC instructions into corresponding x86 instructions. Although there are limits to what programs it can translate, the software promises to ease the transition that current Apple customers and software developers face. Apple Chief Executive Steve Jobs on Monday demonstrated Rosetta during a keynote address, showing it running PowerPC versions of Adobe Photoshop and Microsoft Word and Excel--three applications essential to the success of the Macintosh line.

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What's new:
A Silicon Valley start-up called Transitive is supplying Apple Computer with a crucial bridge to enable the move to Intel-based computers.

Bottom line:
Apple and Transitive face performance challenges. Success has been elusive for computer makers trying to support one chip's software on a machine with a different chip.

More stories on Apple's move to Intel

Jobs' Rosetta demonstration went smoothly--he loaded and edited several documents--but both Apple and Transitive face performance challenges with Rosetta. Success has been elusive for computer makers trying to support one chip's software on a machine with a different chip.

"History says that binary translation basically doesn't work," said Illuminata analyst Gordon Haff. "The day may come when someone can do a good enough job with it, but that concept has been thrown out there many times in the computer industry, and it's always fallen flat on its face."

But Los Gatos, Calif.-based Transitive is willing to set high expectations when comparing software compiled natively for the new processor to that compiled for the older processor and running on the new one.

In the case of Transitive's first customer, Silicon Graphics Inc., software for the older processor generally reaches at least 80 percent of the speed of native software, Wiederhold said. But that high score stems partly from the fact that the SGI systems are used for graphics tasks, which have little or no translation penalty, he said.

With more computationally intense tasks, the performance of translated software is between 60 percent and 80 percent of native software, Wiederhold said.

Another skeptic is Nathan Brookwood of Insight 64. "Everybody always has said 50 (percent) or 60 percent and delivered 30 (percent) or 40 percent," he said. Among those who have tried: Digital Equipment Corp.'s FX!32 to run x86 Windows programs on computers with Alpha chips; Hewlett-Packard's Aries software to run HP-UX software for PA- RISC chips on Itanium; and Intel's IA32-EL software to run software for x86 chips on Itanium.

Jobs was satisfied, though. During his demonstration, Jobs said translated software runs "pretty fast," though his presentation's slide said performance is "good (enough)." His demonstration computer had a 3.6GHz Pentium 4 and 2GB of memory.

Apple, though not known for bending over backward to support users of older Macs, has some experience helping users with processor transitions. When it changed from Motorola 680x0 processors to PowerPC in 1994, it included emulation software that would let users run the older software on the newer machines.

"Like many start-up companies with breakthrough technology, there's a lot of skepticism about the technology itself."
--Bob Wiederhold
CEO, Transitive

And Wiederhold is delighted to have Apple as a customer. "Like many start-up companies with breakthrough technology, there's a lot of skepticism about the technology itself--whether we can meet the claims we discuss," he said. "Getting proof points out there is very important to our success."

One thing that's unclear is whether Rosetta will work in the other direction--translating x86 software for use on PowerPC Macs, something that could significantly expand Transitive's revenue sources. That feature, by ensuring future Mac software will work on older-generation machines, could help convince potential PowerPC-based Mac customers not to put off their purchases.

Transitive last fall released a version of QuickTransit that would support such a feature, but Wiederhold wouldn't comment on whether Apple plans to use it.

However, Apple hopes programmers will create what it calls "universal binaries"--software that includes versions for both processors in one

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