Emulex Corp. Files Countersuit Against Digital : Competition: The Costa Mesa disk drive maker claims that Massachusetts rival sued it only as an attempt to monopolize the computer storage market.

Emulex Corp. said Tuesday that it has filed a countersuit against Digital Equipment Corp., alleging that the Massachusetts computer company is engaging in unfair business practices to monopolize a segment of the computer storage industry. The suit, filed Monday in U.S. District Court in Santa Ana, is a response to a patent infringement lawsuit filed in August by Maynard, Mass.-based Digital against Emulex, a Costa Mesa maker of disk drives and other computer parts.

Digital is seeking an order barring Emulex from making products based on a technology for linking storage devices to computer systems. Such products accounted for 15% to 20% of Emulex’s $153 million in sales last year.

The Emulex suit denies any patent violations and alleges that Digital’s patents can’t be enforced because it obtained them by withholding pertinent information from the U.S. Patent and Trademark Office. Emulex is asking for legal costs plus unspecified damages.

Nikki Richardson, a Digital spokeswoman, said that Emulex’s claims are “without merit.” She called the antitrust lawsuit a “knee-jerk” reaction to patent infringement suits.

Digital says it is protecting its technology, but Emulex and other competitors point out that Digital makes competing equipment and say that it is trying to monopolize the market for itself.

Emulex’s move is the latest in a legal slugfest between Digital and companies that supply equipment for Digital computers and networks. The battle began in April, 1989, when Digital sued System Industries Inc. in Milpitas. The market for such equipment is estimated at between $300 million and $500 million a year.

System Industries agreed to stop making products that use Digital’s patented interconnection technology called SDI/STI--a method for connecting storage equipment such as disk drives to clusters of Digital minicomputers--by the end of 1992.

Digital has also sued Lago Systems Inc. in Milpitas and Micro Technology Inc. in Anaheim for patent infringement. Those companies are disputing the suits.

Since Digital began its legal offensive, 18 other companies have agreed to phase out the offending products by the end of 1992.

Richardson said Digital is pursuing each of the claims separately.