Apple offered a private "technology demo" of a dual-processor Power Mac G4 running Mac OS X on Tuesday, but sources said the company stopped short of announcing a multiprocessor Mac. During a keynote presentation at the Apple Worldwide Developers Conference in San Jose, California, that was open only to developers, Apple executives Mitch Mandich, Phil Schiller and Jon Rubinstein showed off the symmetrical multiprocessing capabilities of the next-generation Mac OS running on a prototype dual-processor machine, sources told ZDNet News. Sources said that in a side-by-side performance demo, the dual-processor prototype ran more than twice as fast as a current single-processor Power Mac G4 system. The company hinted broadly that a multiprocessor Mac was in the works but declined to specify a ship date, sources said, maintaining only that such a system would be available by next year's WWDC, in May 2001. Sources speculated, however, that official announcement of a multiprocessor Power Mac G4 system could occur as early as July's Macworld Expo in New York. Recent software and hardware developments from the Mac maker have raised expectations that a multiprocessor Mac is in the offing. Like earlier PowerPC 601 and 604 processors -- but unlike the PowerPC G3 processor in most current Mac systems -- the PowerPC G4 chip supports multiprocessing, a capability not exploited by the current generation of single-processor Power Mac G4 desktop systems. Furthermore, Mac OS X's roster of promised performance enhancements includes support for symmetrical multiprocessing, a capability that requires the presence of two or more processors. Sources have reported that a dual-processor Power Mac G4 -- code-named Mystic -- have been in the works at least since last summer. During his Monday keynote speech at WWDC -- which, unlike Tuesday's presentation, was open to the public -- Apple CEO Steve Jobs announced that the commercial version of Mac OS X has been pushed back to January 2001 from its planned summer delivery schedule. The company will instead offer a public beta version of Mac OS X this summer, Jobs said. Apple was not immediately available for comment on its multiprocessor road map. Having introduced design sense to the realm of PC hardware, Apple is preparing to repeat the trick in software with its next-generation operating system. Go with Andreas Pfeiffer for the news comment at AnchorDesk UK. What do you think? Tell the Mailroom. And read what others have said. Go to the Apple worldwide developers conference roundup