The long and bumpy road into the computer business took another strange turn for American Telephone & Telegraph Co. yesterday amid speculation that the company was poised to combine forces with NCR Corp.

Both companies declined to confirm a report in the Wall Street Journal that AT&T was negotiating to purchase or form a joint venture with NCR's computer operations, but industry analysts said it is likely that AT&T is exploring any number of avenues to pump up its struggling computer unit.

Reports of the talks helped send NCR's stock up $5.88 to $53.88 in trading yesterday, while AT&T's shares dropped 50 cents to $33.13.

Several industry observers said an NCR-AT&T combination wouldn't seem to offer immediate benefits to either firm, especially NCR. "I don't see what makes them stronger together than apart," said Richard Shaffer, publisher of a computer industry newsletter. More practical, perhaps, would be an arrangement under which AT&T would resell NCR's computers.

Ever since AT&T spun off its local phone operations more than five years ago, it has tried to leverage its electronics know-how into a full-fledged computer business. Revenues have climbed, but the business continues to lose money and has yet to establish AT&T as a major player in the computer industry, analysts say.

NCR, meanwhile, has been attempting to stretch beyond its roots as a maker of cash registers by introducing a new line of computers that can be mixed and matched easily with those of other vendors. Strong overseas sales and a leading position in retailing and in automatic teller machines helped the Dayton, Ohio, company reach $1.5 billion in sales during the most recent period -- a company record for any third quarter.

"NCR is a comer for this decade. It is an old world company contributing to the new world," said George Colony, president of Forrester Research Inc., a Cambridge, Mass., consulting firm. "I see AT&T as a sinkhole for dollars. They have spent millions trying to get into the computer business and they've never been successful."

Analysts estimate AT&T's sales of computers to be between $200 million and $500 million, excluding those it sells to its biggest customer -- itself.

If any alliance with NCR were completed, AT&T would have the most to gain, analysts said. Inheriting NCR's new line of easy-to-connect computers would augment AT&T's strategy to help customers link computers into data networks within a department or an entire company. The networking emphasis has helped AT&T win a number of sales recently, including contracts with Amtrak and United Parcel Service.

Trying to carve itself a permanent place in the computer business, AT&T has over the years aligned with an array of other players, ranging from Italy's Ing. C. Olivetti & Co. to Silicon Valley's Sun Microsystems Inc., in which it owns a nearly 20 percent stake. Still, AT&T seems always on the lookout for more partners and has been rumored over the past few years to be interested in buying a variety of companies, including Digital Equipment Corp. and Wang Laboratories Inc.

"They've studied every one, but they've never done any of them," said Ulric Weil, a Washington industry analyst.