CHICAGO, JUNE 25 -- Motorola Inc. and Hitachi Ltd. said today they have agreed to settle an 18-month legal battle over powerful computer chips that form the brains for several popular computer lines.

The two companies also will jointly seek a stay of a court order barring them from manufacturing and selling the products, Motorola said.

Motorola, based in Schamburg, Ill., charged in a 1989 lawsuit that Hitachi of Japan had infringed on several of its patents and engaged in unfair competition in the sale of computer microprocessors.

U.S. District Judge Lucius Bunton, in Midland, Tex., on June 18 barred Motorola from marketing its M68030 microprocessor. He also barred Hitachi from marketing its similar, but far less widely used, H8532 chip.

A day later the U.S. Court of Appeals in Washington granted Motorola's motion to delay Bunton's order. Motorola said today the two companies jointly will seek a stay of Bunton's order from the appeals court, pending appeal of the case.

Providing the court issues the stay, both companies will continue to supply their customers with the products while they work to complete their agreement to settle the case, Motorola said. A Motorola spokeswoman declined to elaborate on the statement, which said officials of the two companies "have reached an agreement in principle that will serve as a framework" for ending the dispute.

Motorola shipped 500,000 of its M68030 chips last year, yielding what analysts estimated to be $100 million in revenue. The chip is used in the more advanced lines of computers produced by such companies as Apple Computer Inc., Hewlett Packard Corp. and Sun Microsystems Inc.

Hitachi's similar H8532 microprocessor was distributed only to about 200 customers in Japan and to none in the United States, Hitachi has said.

A microprocessor is a digital electronic device that performs the control and arithmetic functions of a computer.