In his speech, Jobs revealed that Apple has been developing all versions of OS X since its inception to run on Intel and PowerPC chips. "Mac OS X has been leading a secret double life the past five years," he said.
The move to Intel marks a tectonic shift for Apple, which has used processors from IBM and Motorola (now Freescale Semiconductor) throughout the life of the Mac. However, the company has changed architectures before, shifting in the 1990s from Motorola's 68000 family of chips to the PowerPC architecture jointly developed by IBM and Motorola.
Jobs also noted the significant effort required earlier this decade when Apple moved from Mac OS 9 to Mac OS X. Although the operating systems are only a digit apart, he noted that the move to a Unix-based system was a major shift. "This was a brain transplant," Jobs said.
The CEO showed a demo of the Tiger operating system on an Intel-based machine, saying, "We've been running on an Intel system all morning."
As for why Apple was making the shift, Jobs pointed both to past problems and to the PowerPC road map, which he said won't deliver enough performance at the low-power usages needed for powerful notebooks.
Two years ago at the same conference, Jobs introduced the first G5-based Power Macs and promised developers that the company would have a 3GHz PowerMac within 12 months. The company still doesn't have a machine that fast. "We haven't been able to deliver," he said. Nor has Apple been able to introduce a G5-based laptop--something Jobs said "I think a lot of you would like."
Things weren't looking better in the coming months, Jobs said, saying that IBM's PowerPC road map would only deliver about a fifth the performace per watt as a comparable Intel chip.
Jobs said there are a lot of products Apple envisions for the coming years, but "we don't know how to build them with the future PowerPC road map."
Jobs added that most of the necessary OS work has been done, but developers will have to do some work to make their applications work on Intel-based machines.
Programs written will require various amounts of effort--from a few days of tweaking to months of rewriting--depending on the tools used to create them.
Some software that's insulated from the underlying chips, such as widgets and Java applications, will work without modification, Jobs said.
Going forward, Mac developers will be able to create universal binaries of their programs that will run on both types of chips.
In the meantime, Apple has a transcoding tool called Rosetta that will allow programs written for PowerPC chips to run on Intel-based machines. "Every application is not going to be universal from Day 1," Jobs told the audience.
A Microsoft executive said the company would create universal binaries with future versions of Office for the Mac. And Adobe Systems CEO Bruce Chizen told developers they can be "absolutely sure" his company would support Apple's transition.
"The only question I have, Steve, is: What took you so long?" Chizen said.
Also on Monday, Jobs said the next version of OS X, called Leopard, will be released in late 2006 or early 2007. That is the same time frame as Microsoft's next Windows update, dubbed Longhorn, he noted. Microsoft has said Longhorn will be released by late 2006.
After Jobs' presentation, Apple Senior Vice President Phil Schiller addressed the issue of running Windows on Macs, saying there are no plans to sell or support Windows on an Intel-based Mac. "That doesn't preclude someone from running it on a Mac. They probably will," he said. "We won't do anything to preclude that."
However, Schiller said the company does not plan to let people run Mac OS X on other computer makers' hardware. "We will not allow running Mac OS X on anything other than an Apple Mac," he said.