BRUSSELS, Belgium -- Microsoft Corp. said software developers would no longer need to pay or license technology it provides to help one computer run multiple operating systems at the same time.

It said it would provide access to a "virtualization" format on an open-source basis, saying this was the best way to get the broadest audience for its own specifications. The technology makes it easier for users to access programs or look at documents made by non-Microsoft vendors.

Demand from customers -- particularly in the government sector -- who use open-source servers such as Linux was one of the main reasons for the company to move toward open-source standards, said Microsoft spokesman Tom Brookes.

He said it was not connected to Microsoft's rows with EU regulators over supplying interoperability information to rivals.

The company will no longer ask developers to sign a license agreement. They are already offered the standard without cost.

Microsoft cited a study from research group International Data Corp. saying it expected about 500,000 servers equipped with the virtual hard-disk technology would enter the marketplace this year, up from roughly zero just three years ago. The study showed that by 2009, about 1.2 billion machines should be equipped with the technology.

Microsoft's past reluctance to share technical information that helps developers make server software that works smoothly with the ubiquitous Windows operating system was one of the sources of its long-running antitrust battle with EU regulators.

The 25-nation bloc levied a record $613 million fine on Microsoft in 2004 when it ordered it to hand over server protocols to rivals, saying it had deliberately tried to cripple them as it won control of the market.

In July, regulators fined the company another $357 million and threatened more penalties, saying Microsoft failed to obey the 2004 order. Microsoft is appealing both the fines and regulators' conclusions that it was guilty of breaking EU antitrust law.

Security vendors Symantec Corp. and McAfee Inc. last month made similar complaints that Microsoft was withholding interoperability information on its forthcoming Vista operating system. Microsoft said Monday it had provided them with some of the code they were looking for.