A year or two from now, many manufacturers, including Thomson, will begin offering several more models. Some will provide a full high-definition picture without all of the expensive extra features. By then, the integrated circuits needed to translate and display the digital signal, now a rarefied and expensive piece of circuitry, will almost certainly have dropped in price considerably.

Today the chips alone contribute $2,000 or more to the retail cost of an HDTV. But these chips should respond to Moore's Law, the computer-industry guideline that says a microprocessor's capability will double, and the price halve, every 18 months.

Given the universal appeal of televisions -- far greater than that of computers -- Mr. Perry, the Mitsubishi executive, said he believed the cost of the microprocessors will drop by 50 percent each year for the next three.

Mr. Knox said an HDTV will probably sell for $3,000 by 2002. Mr. Milbourn said he believed his company would sell an HDTV for half the current price by the time the second-generation models come out in a year or two. Mr. Perry said ''they'll cost $3,500 a couple of years from now.''

That's certainly better than $8,000, but still out of the reach of most television buyers, who now pay $500 or less on average for a new set. In fact, Mr. Thibodeaux's research shows that consumer electronics products reach true mass acceptance only after the price falls below $500.

And how long before the industry is able to sell a high-definition television set for $499.95? Within the industry, that question generally is greeted with heavy sighs and pessimistic shakes of the head. No one is willing to even guess.

What You Should Know

The introduction of high-definition television will bring changes for TV viewers. Here are the answers to some questions about those changes:

Q. When will the first high-definition televisions go on sale?

A. Several manufacturers have pledged to put their first models on the market next month, and others will come through the fall and winter. By January or February 1999, almost all major consumer-electronics manufacturers should have sets for sale.