Cheaper, but high-powered, personal computers are beginning to shove the larger and more expensive minicomputers aside in the data-processing marketplace.

The combination of improved memory storage, faster processing times and the ability to link dozens of personal computers into a communicating network is making data-processing managers think that they now can buy personal computers at prices below those of minicomputers to satisfy their information-processing needs.

"The bottom line is clear," asserted William F. Zachmann, an industry analyst with International Data Corp., in a recent report. "Microprocessor-based systems, local and work area networks, and a growing collection of effective standards are combining to make the price/performance ratios of traditional systems hopelessly uncompetitive."

Minicomputers -- the class of computers just below the powerful mainframe computers -- are seen as particularly vulnerable to personal-computer competition. Minicomputers traditionally have been used as a "departmental" computer in companies, serving the processing needs of dozens of users.

Of the $60 billion spent on computers worldwide in 1984, nearly 40 percent was spent on minicomputers. Approximately one-third was spent on personal computers, according to a report by International Data Corp.

Analysts such as Zachmann point out that networked personal computers attached to a "file server" -- a data storage box -- could be as functional as a minicomputer system, but at a fraction of the cost.

"Absolutely," said Esther Dyson, an industry consultant and editor of a personal computer publication. "Look at the lines: The micros are going up, and the workhorse minis are having a tough time. It's hard to compete with an IBM PC-AT for price performance."

Dyson pointed out that leading minicomputer companies such as Data General Corp. and Digital Equipment Corp. recently introduced new higher-speed, higher-powered minicomputers to further distance themselves from the specter of personal-computer competition.

Moreover, DEC, the nation's second-largest computer company after International Business Machines Corp., recently introduced its Microvax II personal computer -- a relatively low-cost personal computer that in many respects is a desktop version of its main VAX line of minicomputers. Many analysts consider that a defensive move to assure DEC a place in the personal-computer market.

"We wanted to push the VAX family into price bands that can reach more people," said Richard A. Loveland, DEC's manager of product planning for office and information systems.

But Loveland disputed assertions that personal computers -- even DEC's own Microvax -- will displace minicomputers. "We pick personal computers to be handling new functions rather than replacing mini functions per se," he said.

In fact, DEC believes that personal computers will help drive minicomputer sales, arguing that minicomputers will be used as central coordinating computers for clusters of personal-computer networks.

"Personal computers don't talk to each other," Loveland said, "They communicate through an intermediate box. Minicomputers will be used as those boxes in the future."

Indeed, he said, DEC recently began adapting its minicomputers to become file servers for personal computers. Loveland conceded, however, that the rise of personal computers gradually is redefining the role and mission of the traditional minicomputer.

"The minicomputers are now adjusting to personal computers," agreed Bob Metcalfe, chairman of 3Com Corp., a personal-computer networking company based in Mountain View, Calif., that recently merged with Convergent Technologies, a minicomputer company.

But Metcalfe, who described local-area networks as "the minis of the 80s," agreed that, on balance, personal computers will boost minicomputer sales rather than compete with them."