About five years ago, a Georgia firm called Microstuf came out with a fine new communications program for personal computers called "Crosstalk." It rapidly became the industry standard for communications software -- that is, the programs that run your computer and modem when you're communicating with another computer, a remote data base or an electronic bulletin board.

With their product established as a hit, the folks at Microstuf made an enormous commercial blunder. They sat back on their laurels. While other successful software houses -- Microsoft, Borland and that ilk -- worked assiduously to update and improve their products, Microstuf contented itself with a few minor changes to Crosstalk now and then. While other software vendors were moving toward prices well under $100, Crosstalk stayed closer to $200.

Now Microstuf is paying the piper. In a classic demonstration of the way the free market is supposed to work, an industrious group of entrepreneurs has stepped in to fill the void left by Microstuf's lassitude. The result is a new $50 program called "Mirror" that is nothing more -- and nothing less -- than a better Crosstalk. Mirror is an improved version of the familiar program at a much more attractive price.

There's nothing particularly subtle about the folks who make Mirror. They call their company "Softklone Distributing Corp." (1210 E. Park Ave., Tallahassee, Fla. 32301), and they tell you exactly what Mirror is all about on the second page of the user's manual: "MIRROR is a clone of the Crosstalk XVI program copyrighted by Microstuf Inc."

"Clone" is not a bad description. Running Mirror is almost identical to running Crosstalk. Anybody who has used Crosstalk can start in on Mirror instantly without opening the Mirror manual. Script files -- that is, sets of commands the program uses to place and receive calls automatically -- that run on Crosstalk run perfectly on Mirror with no changes.

I have found Mirror to be just as flexible and just as reliable as Crosstalk -- more so, in fact. My particular version of Crosstalk has always had a lot of trouble using the "XMODEM" transfer system to "download" (that is, to receive) programs from remote data bases; on Mirror, by contrast, my "XMODEM" transfers have worked beautifully every time.

The many readers who have written this column about their problems getting connected to the Nexis/Lexis database will be pleased to know that Mirror comes equipped with a built-in script file that will automatically connect to Nexis. I didn't have high hopes for this feature because I've had dismal luck trying to connect with Nexis using the Crosstalk program; yet I found that Mirror can call Nexis without a glitch. Mirror isn't a total "clone" of Crosstalk, though. In some important ways, it's better than the original. The programmers who wrote Mirror included some valuable features that Crosstalk lacks -- features that the people at Microstuf never got around to including with Crosstalk.

Unlike Crosstalk, Mirror has a built-in word-processing editor. You can compose new script files or edit files you receive over the modem without the need to exit the program and load a separate word-processing package. This is such an obvious improvement you would think the people at Microstuf would naturally have come up with it themselves. But Microstuf was asleep at the switch, and Softklone has taken advantage of the resulting commercial opportunity.

Mirror also can run in "background" mode; that is, while Mirror is sending or receiving a long file, you can put the program in "background" and then work on some other program until Mirror signals you that the long file transfer has been completed. Microstuf didn't bother to add this feature to Crosstalk.

Mirror has some oddities, including a troubling tendency to keep redialing a number automatically after you've told it to stop. On the whole, though, it is an excellent product and a real bargain.

How has Microstuf reacted to this formidable new competitor? I'd like to report that the company responded in the free market spirit -- by cutting its price, for example, or improving its product to regain the industry lead. Sadly, however, Microstuf has spurned the free enterprise approach.

Instead, Microstuf has hired some high-powered lawyers and hauled Softklone into court for alleged copyright violations. Not to put too fine a point on it, this contention is absurd. There were lots of communications programs around before Crosstalk; more have come along since Crosstalk was written.

They all use essentially the same set of microprocessor instructions, and nobody before has had the gall to claim a "copyright" monopoly on this exceedingly common type of program.

I hope that Microstuf's blatantly anticompetitive gesture will get short shrift in the courts. But these things are hard to predict. If you need a good modem program, you might think about buying Mirror right quick -- before the legal system has a chance to boot it off the market.