SAN FRANCISCO (Reuters) - Intel Corp.'s INTC.O Itanium and Itanium 2 microprocessors use technology developed by computer-service firm Intergraph Corp. INGR.O , a judge ruled on Thursday, a decision that could cost the world's biggest semiconductor manufacturer as much as $250 million.

A U.S. federal court ruled that Intel, based in Santa Clara, California, had infringed on two patents held by Huntsville, Alabama-based Intergraph. Intergraph's lawsuit alleged that Intel had violated patents covering so-called parallel-instruction computing, or PIC.

The PIC technology is used in Intel's Itanium chips, which are designed for high-end, heavy-duty computing, and crunch data in 64-bit chunks compared with 32-bit chunks crunched by Intel's Pentium processors.

In his ruling, Judge T. John Ward of the U.S. District Court for the Eastern District of Texas, in Marshall, Texas, found that both Intergraph's patents are "valid and enforceable."

"Intel respectfully disagrees with the judge's ruling," said Intel spokesman Chuck Mulloy. He said that the ruling is not yet final, and Intel plans to file a motion for reconsideration. If Intel does not prevail there, Mulloy said Intel plans to appeal Judge Ward's decision.

Intel had settled in April 2002 a 1997 Integraph suit for $300 million relating to alleged patent infringement by Intel on Intergraph's Clipper-chip technology allegedly used in Intel's 32-bit Pentium chips.

As part of that settlement, both sides agreed to break off the allegations related to 64-bit technology and try that case separately.

"This ruling validates Intergraph's patents, and paves the way for Intergraph's intellectual property division to actively pursue open licensing with others throughout the consumer electronics and computer industries," said Intergraph Chairman and Chief Executive Jim Taylor in a statement.

If Intel loses the motion for consideration, it must pay $150 million to Intergraph, under the terms of the April settlement, Mulloy said. If Intel appeals and loses, it must pay an additional $100 million to license Intergraph's technology.

If it prevails on appeal, Intel will pay nothing, yet also receive a license to Intergraph's PIC technology covered by the two patents at issue, Mulloy said.