Microsoft must comply within 90 days. The injunction does not involve software that has already been shipped and sold. Although most computer users will be unaffected by the court order, the modifications will allow programmers more flexibility in the systems they use.

More broadly, the ruling sends a message to the industry that Microsoft's strength can be challenged in court. Sun Microsystems, based in Palo Alto, sued Redmond, Washington-based Microsoft last October, seeking the changes and $35 million in damages for allegedly developing and distributing a Windows-only form of the language.

JAVA, introduced by Sun in 1995,potentially allows developers to write a software program once and have it run on a wide variety of computer systems including Macintosh, Unix and Windows. But Microsoft rewrote JAVA, when it included the language in its software, so that it would only work on Windows.

Paul Maritz, Vice President for Microsoft's Platforms and Applications group, said new shipments of `Windows 98' would be modified to comply with the order. He would not estimate the cost of changing the software, other than to say it was ``well within our capabilities.''

The case is still headed for trial, although no court date has been set. Microsoft legal counsel Tom Burt said Microsoft was still studying the ruling and might appeal. Microsoft officials also said they are considering simply pulling JAVA off their software.

Sun, however, said it has a 5-year contract with Microsoft to include the language.

In the lawsuit, Sun Microsystems accused Microsoft of trying to make it impossible for JAVA to become a universalprogramming language.

Sun's complaints are echoed in part of the Justice Department's litigation against Microsoft in an ongoing Antitrust trial. But both Sun and Microsoft officials said they didn't think Tuesday's ruling in San Jose would bring any changes in the case in Washington, D.C.