Apple Computer Inc., abandoning its historic practice of running only its own operating system on its personal computers, yesterday rolled out software enabling buyers of Apple's new Intel-based Macintosh computers to install the Windows platform built by rival Microsoft Corp.
The move, which caught much of the technology world by surprise, was seen as a bid to boost Apple's share of the PC market -- estimated at less than 5 percent -- by reaching beyond its base of Mac loyalists to the larger universe of ordinary computer users more familiar with the ubiquitous Windows.
''It's a huge departure," said Ted Schadler, vice president and principal analyst at Forrester Research in Cambridge. ''It's a big deal. But it's tied to their business model: Apple is a hardware company."
Schadler, who posted a blog entry yesterday titled ''Apple Runs Windows, Pigs Fly," projected that Apple could double its market share by appealing to consumers who first learned Windows on office computers and later bought home computers powered by Windows. Many have been drawn to Apple Stores over the past few years to buy iPod music players and have admired Mac designs, but they are intimidated about switching to Mac OS.
Down the road, Apple could target the bigger market of businesses and other enterprises by licensing, supporting, and pre-installing Windows on future Macs, Schadler suggested.
Investors bid up Apple stock yesterday, lifting shares 9.9 percent, or $6.04, to $67.21.
The enabling of the Windows XP operating system, through a new software known as Boot Camp, stems from Apple's recent switch in its new MacBook Pro notebook computers and Mac Mini desktop computers to the Intel microprocessors also used in the Windows systems that run on Dell, Hewlett-Packard, and other personal computers. Apple had used IBM PowerPC processors.
Apple's new Intel-based computers will continue to run Apple's OS X operating system. But users who also want to run Windows, and the many applications available only on Windows, can boot the Microsoft system with a Windows XP installation disc and a download of the Boot Camp beta software from apple.com/macosx/bootcamp. The software will be available on a trial basis through Sept. 30, 2007, said Natalie Kerris, an Apple spokeswoman. But a final version of Boot Camp will be included in Leopard, the forthcoming version of OS X. Apple hasn't disclosed a timetable for releasing Leopard.
Boot Camp will not enable users to run Windows XP and Mac OS X simultaneously, Kerris said. But once installation is complete, users can restart their computer to run Mac OS X or Windows XP.
Analysts yesterday said it was unclear whether Apple intended to make its Windows move when it switched to the Intel chips or if its hand was forced by hackers in the Mac world who'd fashioned so-called ''bootloader" programs to port Windows to the new Intel-based Macs.
However it arrived at its decision, they said, the Apple move presents an opportunity to narrow the wide market advantage now enjoyed by Microsoft.
''Apple recognizes that not being able to run Windows programs has created a hurdle for them in trying to attract Windows users who might want to move to a Mac," said Nitin Guptal, media and entertainment analyst for Yankee Group research firm in Boston. ''The popularity of the iPod has brought people into the Apple stores, and they see these really nice looking computers. But it's too much of a jump for them because they have to learn a whole new operating system."
In the near term, Boot Camp could be a boost for Microsoft because it would extend the reach of Windows XP, though Apple is clearly hoping it will gain longer-term benefits by drawing more computer users into the Mac camp. ''Windows is a great operating system," said Kevin Kutz, director of Microsoft's Windows Client division in Redmond, Wash. ''We're pleased that Apple customers are excited about running it, and that Apple is responding to meet the demand."
Every share Apple gains in the PC market would translate into roughly $2 billion in revenue and 30 cents in earnings, estimated Bill Shope, vice president and senior analyst at J.P. Morgan Securities in New York. Shope said yesterday's move was ''one of the top five major announcements" in the 30-year history of Apple, joining with the unveiling of the original Macintosh, the return of chief executive Steve Jobs, and the introductions of the iPod and the iTunes Music Store.
''They've always been a closed system," Shope said of Apple. ''Now they're showing some degree of openness. It also could be something of a Trojan horse. Once you capture that Windows customer, you have the opportunity to draw them into the whole Mac ecosystem."
Robert Weisman can be reached at email@example.com.