HP said it believes Oracle's March 22 decision to discontinue all future software development for Itanium violates "legally binding commitments" that Oracle made to HP and the companies' 140,000 joint customers, HP said in a statement.

"Further, we believe that this is an unlawful attempt to force customers from HP Itanium platforms to Oracle's own platforms," HP said.

HP in the Superior Court in Santa Clara, California, in a bid to force Oracle to reverse its decision. HP believes Oracle is "legally obligated" to keep developing its software for Itanium, HP said.

Oracle shot back that HP's claims are untrue and accused HP of tricking it into signing an agreement last September to continue its support for Itanium, even though HP knew of an Intel plan to discontinue Itanium.

"We believe that HP specifically asked Oracle to guarantee long-term support for Itanium in the September of 2010 agreement because HP already knew all about Intel's plans to discontinue Itanium, and HP was concerned about what would happen when Oracle found out about that plan," Oracle said in a statement.