LAS VEGAS -- Maybe you had to be here to understand. But for some reason, when IBM hired a team of five synchronized skywriters to paint a two-mile-long advertisement in the deep blue sky above the Las Vegas Strip, it seemed a perfectly fitting thing to do.

Of course, this display of dot-matrix skywriting was an excessive piece of showmanship. But then, wretched excess and outrageous showmanship were the watchwords when the personal computer industry gathered here last week for its annual autumn bash, the COMDEX exposition. PC people are celebrating record worldwide sales of hardware (an estimated $40 billion this year) and of software (an additional $25 billion, by some estimates).

The celebration was a huge event, with thousands of companies showing off their new stuff to tens of thousands of dealers and users. There were so many new products that it would fill a half-year's worth of columns if I just gave a single sentence to each one. But a few overall industry patterns stood out.

Even before it launched that five-plane skywriting extravaganza, IBM clearly was the dominant force at this year's COMDEX. Big Blue reported that it already has shipped 1 million of the Personal System 2 computers it announced in April. And sure enough, on the sprawling exhibition floor here, every other booth seemed to trumpet somebody's new "PS/2 compatible" peripheral or software.

There were, of course, thousands of hardware and software products on display for the existing base of MS-DOS machines. Some manufacturers still are coming out with new clones of the original IBM PC or XT. But the momentum at this show clearly was running toward the PS/2 standard and its companion operating system, OS/2. That is, IBM may again prove itself capable of imposing a new standard on the industry.

In contrast, Apple and its Macintosh had a much lower profile at the show. I was particularly disappointed at the various displays of color monitors for the new Mac II, which looked pretty feeble next to the gorgeous color graphics already running on MS-DOS and PS/2 machines. No doubt Apple and its software vendors will remedy this, but for now the Mac II is hardly a player in the color display sweepstakes.

By contrast, Apple's stunning new data management program, Hypercard, already has had a major impact on the industry.

Many companies were showing off MS-DOS versions of Hypercard and the hypertext approach to data management. The heavy hitter was Lotus, which was showing an early version of its new Agenda program, which is supposed to help people manage large amounts of information.

One significant problem in the rush to embrace hypertext-style data management is that nobody really has a good definition of what "hypertext" means. I thought the confusion was illustrated nicely by a new word-processing program called Black Magic, which is described by its author as "word processing using hypertext which is based on non-sequential writing." Non-sequential writing?

There still are no Macintosh clones, but I was greatly impressed by the new Macintosh lookalike from Atari, the Mega ST. This is a fast, powerful computer that can run any software -- including all the spectacular color games -- written for earlier Atari ST models. There also is business software for the Mega ST -- word processing, spreadsheet and the inevitable "hypertext" -- which feels and runs very much like similar programs on the Macintosh. And the Atari machine is much cheaper.

Two product lines that would have sparked enormous interest two years ago, but provoke a ho-hum reaction now, are lap-top computers and laser printers. There were so many new models of each that it was difficult to remain interested, particularly since every lap-top looks pretty much the same.

The competition is having a salutary effect on prices, however. I saw several two-disk-drive, 640K lap-tops priced under $1,000; just last spring, I would have been excited to see such a machine at the $1,500 level. There is no sub-$1,000 laser printer yet, but that day will come, probably some time next year.