LAS VEGAS -- There hasn't been much joy on Wall Street in recent weeks, but the microcomputer industry is determined that even downturns in the Dow Jones industrial average won't dampen its hard-won resurgence.

Makers of personal computers are vulnerable on two fronts to a slump: cutbacks in capital spending by companies, and retail sales to private consumers. Despite this, the rhetoric at the industry's annual fall COMDEX show in Las Vegas was upbeat.

Optimism apparently was handed out with the badges to the more than 100,000 attendees at the industry extravaganza, many of them dealers, retailers, distributors and national customers who visited the 1,500 booths to place orders for the coming year.

"I won't say I wasn't worried on Oct. 19 about what this meant for next year's sales," said Jeff McKeever, president of MicroAge Computer Stores Inc. in Tempe, Ariz. "But from all the activity I've seen here and from what I've been told about forecasts made by economists at IBM and AT&T, I don't think there is going to be any cutback in capital spending for next year."

James Manzi, chairman and chief executive of Lotus Development Corp., closed his keynote address with fighting words that became the theme of the show.

"Looking around at COMDEX, I can see that we have everything going for us to do gangbuster business in the coming year, recession be damned," he said.

Yet despite the ebullience on the show floor, some concerns clearly lingered. The bottom had fallen out of the market just when the long-suffering PC industry had managed to punch its way out of its own two-year shakeout.

"It is ironic that the economy faces a downturn at the precise moment when our industry is coming to the marketplace with its first real breakthrough in years, just when we're able to deliver on promises of speed and memory with new processors and operating systems," Manzi said.

The stock market downturn was as much a topic of discussion as OS/2, MIPS and CD-ROMs. But when it was put in the context of skyrocketing sales and a year-long flurry of new products by industry standard bearers, the computer manufacturers were able to keep happy faces.

In the past, the PC industry has moved contrary to the rest of the economy, getting its first real surge of growth during the 1981 and 1982 recession, and falling into a prolonged slump during recent bullish activity in other sectors of the economy.

Not only is the PC business capital spending-intensive now that computers have become a ubiquitous tool on corporate desktops, but in the last year the long-awaited, home-professional computer market has also finally caught fire.

Yet reports of any immediate damaging effects were few.

Robert Elster, a Hoffman Estates, Ill.-based district manager for Kaypro Corp., said that of his 50 dealers in the area, "the larger ones reported their walk-in traffic was crippled immediately after Black Monday. Large business deals likewise fell through the cracks. A lot of purchases were put on hold fast," he said.

"Those that were hit were hit really bad."

Yet Elster said that while some dealers reported such negative effects, most said they saw little or no reaction to the quakes on Wall Street.

One of his dealers at the show, Bruce Reudig of C.A.S., a Chicago area chain that sells IBM clones and used computers and has a large walk-in clientele, reported that he'd had "the best two weeks ever at the end of October. I have no idea why."

Most analysts believe the fourth quarter will remain strong no matter what happens, since corporate budgets are already in place. Consumer spending, they say, will suffer only modestly.

"We expect strong growth in the business market for the next several quarters," said Michelle Preston, a securities analyst specializing in the PC industry and a vice president of Salomon Brothers Inc. in New York. "Shortages of key products dominated the industry in 1987, and we will see increases in production as a result. Many of the new products introduced here should fuel strong demand."

But others were less enthusiastic. "We're bound to see some slowing demand in the industry," said Richard Shurland, a securities analyst and vice president with Goldman, Sachs & Inc. in New York. "The scenario we see across the economy is that consumers will retrench, causing corporate profits to dip, slowing the rate of spending on capital equipment.

"But new product cycles will help mitigate that for the personal computer industry. The bottom line is that it is going to be a tug of war next year."

Most large customers come to COMDEX to talk about the first quarter and beyond. Such activity was boisterous and fast-paced.

At the Zenith Data Systems booth, a spokesman said the Glenview, Ill.-based computer manufacturer had seen twice the number of customers in the first day that it has seen during the entire five-day show in past years.

"The PC and MS-DOS are five years old," said John Frank, president of Zenith Data. "Most of those machines are fully depreciated. They are being moved out and replaced. All indications point to sales going straight up. Even the stock market can't stop that."

"We haven't even had time to discuss the stock market crash, we've been so busy," said a salesman at the Wang Laboratories Inc. booth.

Outside of Comdex, the chairmen of at least two major players in the industry said recently in separate quarterly securities analysts' meetings in New York that their October sales were unaffected by the sudden downturn, and their projections for the first quarter of 1988 remain strong.

Yet both John Sculley, chairman and chief executive of Apple Computer Inc., and John Akers, chairman and chief executive of International Business Machines Corp., told analysts that while they were optimistic, they had contingency plans in case the economy should go sour.

Ben Rosen, chairman of Compaq Computer Corp. and Sevin Rosen Management Co., a venture capital firm, said 1988 could be a great year for the industry.

"We've only penetrated 20 percent of the market, and major new software is going to spur buyers to upgrade their current products," he said. "What could happen is that the growth rate may diminish -- but it will still be substantial."

"So what if our annual growth rate drops from 30 percent down to 20 percent? I'd still rather be in this industry than selling shoes or cars," said Ken Wasch, executive director of the Software Publishers Association in Washington.endqua