Digital’s Line to ‘Talk’ to Rivals’ Computers : Technology: The company is abandoning its strategy of making models that are incompatible with other lines. Sales have been lagging.

Digital Equipment Corp. said Monday that it plans a major shift in strategy toward the “open” computer standards that are gaining increasing popularity in the computer industry.

Analysts said the world’s second-largest computer maker was pushed into the change by a slumping market for its machines, which cannot easily be connected with computers made by other companies or operate their software.

Digital will announce Thursday that it will modify its mainstay VAX computer line to run software designed for the popular Unix operating system.

That means companies equipped with both VAX and Unix-based computers could run the same software on all, saving the cost of buying or writing a second version of the software.

An operating system is the base layer of software than controls a computer’s internal housekeeping functions. Applications software, such as word processing programs, enables computer to perform specific functions. It runs on top of an operating system.

Digital said it will release a version of its VAX operating system next year that will adhere to an open-system standard called Posix. Posix, in turn, is compatible with Unix.

Analysts said Digital, based in Maynard, Mass., needs to make its VAX computer line more attractive.

“There is clearly a slowdown in orders for VAX,” said Jay Stevens, who follows the computer industry for Dean Witter Reynolds Inc.

Part of that sluggishness is due to the desire for open systems, but it also is due to a delay by customers in ordering new Digital computers while they await promised new models, analysts said.

One such model, also to be announced Thursday, is a new top-end version of the VAX 6000 mid-range computer line. The VAX 6000 model 500 will offer 85% more processing power than the current top-end 6000, but cost only 18% more, said Stephen Blanchette, the line’s marketing manager.

Digital admits that the move to open systems is driven by the marketplace.

“It is apparent that open-systems computing is the way of the future, and Digital intends to address that market,” said Phil Auberg, marketing manager for the VAX software line.

While Digital’s move is important for a company that has relentlessly promoted a proprietary computer line, it isn’t unique. NCR Corp. made perhaps the most dramatic move into open systems of any old-line computer maker with an announcement last month that it will replace its entire product range with open-system machines.