At an interoperability conference in Brussels, the software giant said that its Virtual Hard Disk (VHD) Image Format specification can be used by third parties without the need for them to get a commercial license.
The virtualization technology will be available under the terms of Microsoft's.
The promise, similar to other pledges not to sue over patents, allows developers to create software based on the Virtual Hard Disk format without fear of infringing on Microsoft patents, company executives said.
"This is Microsoft's personal promise to any individuals or organizations in the world that they can use patented technologies that could be in this VHD technology," said Jean Paoli, the manager of interoperability and XML architecture at the software maker.
Until now, Microsoft has licensed the technology to other software companies for free. The new system cuts out the need for outsiders to sign a commercial license with Microsoft, executives said.
Virtualization allows a single server to run multiple instances of an operating system or other program. It has become a popular way for businesses to cut down on hardware costs by consolidating several computing jobs onto fewer servers.
Microsoft's Virtual Hard Disk file format stores information on the state of an application and operating system while the program is running. It is used to start or turn off instances of an application running on a virtual machine.
By making it easier to tap into the Virtual Hard Disk format, Microsoft hopes to encourage developers to make use of the technology. For example, an independent software company could build a way to monitor virtualized Windows servers or to create an edition of the file server for other operating systems, Paoli explained.
In September, Microsoft said that a broad range of Web services protocols, which were developed with Microsoft and others, are covered under its Open Specification Promise.
Tom Robertson, Microsoft's general manager of interoperability and standards, said that Microsoft expects to use the OSP for other technologies.
"This is not an isolated activity--it's part of a broader, well-considered set of activities," Robertson said. "This fits into our work on giving access to technology."
"There is general agreement (within Microsoft) that thetoday is absolutely the right direction. But the specific steps we'll take are a matter of discussion, and they're not always easy issues to tackle," he added.