An early convert to the IBM-PC was a San Francisco lawyer, writer and Renaissance man named Andrew Fluegelman. There was little off-the-shelf software for the PC in its early days, so Fluegelman wrote his own, in Basic. He didn't know he was about to invent a concept that would help shape the personal-computer revolution.

Fluegelman needed a way to exchange text files over the telephone with a man in another state with whom he was collaborating on a book, so he wrote a modem-communications program to do the job. He passed out copies of the program to friends to see how they liked it.

They liked it so much so that the program, dubbed PC-Talk, spread rapidly through the growing community of IBM-PC user groups and on-line bulletin boards. Fluegelman kept improving the program and passing on the upgrades free, until one day he hit on an idea.

It was to put an onscreen message in the software requesting voluntary contributions from those who used it regularly. Many people continued to use it and pay nothing, but many also sent money. Thus the concept, which he called "freeware," more commonly known today as "shareware," was born. Shareware continues to occupy a major place in software for all kinds of personal computers, but nowhere is the selection richer than in communications programs for the IBM-PC and compatibles. Since Fluegelman's untimely death in 1986, PC-Talk has been overtaken by other programs, but its imprint is visible on nearly all of them.

The genius of PC-Talk was that it was easy. Its principal commands were combinations of the ALT key with a letter key. ALT-X, for example, to exit the program, ALT-T to transfer a file, ALT-R to receive one. ALT-D, for dial, brought into play PC-Talk's most imitated feature, the dialing directory.

A numbered list of names and phone numbers appeared on your screen. It was simple enough to add numbers or edit entries and each entry contained the appropriate settings for the other computer to be dialed. Then, when the dial command was issued -- by picking the appropriate entry and hitting a key -- the program automatically adjusted your modem to the appropriate settings.

The most successful of PC-Talk's successors is Procomm, from Datastorm Technologies of Columbia, Mo., which went through a series of shareware editions before becoming a purely commercial product, Procomm Plus, now in the newly released version two.

Procomm has all the familiar PC-Talk features, and many more, and, written in the C programming language, executes much faster. It supports nine different "protocols" to check for and correct errors in file transfers. The program also imitates no fewer than 11 different types of computer terminals.

The shareware versions of Procomm, which ended at version 2.4.3, support what were called "command files," which could be linked to entries in the dialing directory. Command files are simple text files containing a series of instructions, much like a DOS batch file, to allow automatic sign-on to another computer, and the execution of a specific task, such as transmitting a file.

All these features are present in Procomm Plus 2.0, and more. There are no fewer than 33 computer terminals emulated, and 15 file transfer protocols. The simple "command" files to log on to other computers have grown into a very powerful and complex programming language called "Aspect," which allows the automatic execution of highly intricate on-line sessions.

Programming in Aspect is not for the computer faint-of-heart, but creating a simple automatic log-on sequence is no more difficult than writing a command file.

Most of the program's noted ease of use has been preserved. There are, however, a few cases where an additional step is required. For example, when you bring up the dialing directory, you can't simply enter the number of the entry you want to dial and hit the enter key, you must first hit "D" for dial. Minor, perhaps, but annoying to someone used to the quicker method.

An important new feature is extensive mouse support in Procomm Plus II. A touch of a mouse button puts a set of pulldown menus across the top of the screen. You can navigate among them with the mouse, and once you've established a connection, perform most functions by invoking the menus again. The menus also can be used from the keyboard.

The program's online help -- that is, help available from within the software -- has been expanded greatly from the simple command table featured in the shareware edition. Now you can call up specific instructions about what you're doing at any time.

All this might seem like more features than a communications program needs, and perhaps it is. But you don't have to use any more than you need and at $119, it's a good value. For a better bargain, get the shareware edition.