Comdex, the world's largest computer trade show, has shrunk.

Aisles that last year were packed shoulder to shoulder with entrepreneurs, venture capitalists, retailers and businessmen were conspicuous by their open spaces on the first day of the five-day event at the convention center here.

The estimated 15 percent drop in attendance, which Comdex officials downplayed, reflect the continuing shakeout and lackluster growth of the computer industry this past year.

"Reality has replaced the thrills," said one Digital Equipment Corp. manager.

While the atmosphere at Comdex was sober, dozens of companies introduced new and fairly innovative products designed to position themselves in some of the industry's few fast-growing segments.

Desktop publishing -- linking personal computers to printers that allow people to produce professional-quality documents and reports -- has spurred both interest and investment by some of the largest companies in the information processing industry.

"Clearly, this is a market that's growing very rapidly," said Eric Hope, the vice president of market development for the business systems group at Xerox Corp. "It should grow from roughly 100,000 to 200,000 units sales this year to about a million units a year by 1989."

The emergence of desktop publishing undercuts claims by office-automation experts just a few years ago that personal computing would inevitably lead to the "paperless office."

"For the first time, a department or a company can become its own publisher for under $10,000," said Amy Wohl, an industry commentator, who adds that desktop publishing is one of the areas where personal computers and printers are demonstrably cost-effective.

The driving technological force behind the desktop publishing movement is the "nonimpact" printer, such as the laser printer or ink-jet printer that, in essence, paints letters, numbers and charts on paper. Unlike impact printers -- using daisy wheels or dot matrices -- nonimpact printers generally make it easy to print text, charts, graphs and pictures on a single page.

In effect, nonimpact printers appear to be more cost-effective for high-quality document printouts rather than only pages of text.

More than a dozen companies at the show are introducing nonimpact printers and the number of nonimpact-printer companies at Comdex jumped from 27 last year to 36 this year.

"While nonimpact printers should enjoy the fastest growth," said Xerox's Hope, "I see them as a complement to the existing installed base of impact printers. There's room for both, depending upon what kind of printing you need to do."

However, as in the personal computer field, many in the printer industry anticipate the onslaught of price wars within the next 18 months as a result of Japanese and Korean competition.

"It's inevitable," said Loyd Tarver, marketing vice president for Diconix Inc., an Eastman-Kodak subsidiary that is introducing a $12,000 high-speed ink-jet printer at the show. "That's been the pattern."