But unlike commercial software ventures, GNU programs are distributed with source code, the original programmer's instructions. This permits any user to modify the program or improve it. While most software companies jealously guard their source code, Mr. Stallman argues that by freely sharing it he has created a software community in which each programmer contributes improvements, thereby bettering the program for all.

Mr. Stallman, who likes to be called by his initials, R.M.S., forged his values as a member of an elite group of M.I.T. computer hackers who, during the 1960's and 70's, conducted pioneering research in developing the world's first minicomputers and the first time-sharing computers. M.I.T., which is where the term hacker was born, also served as the incubator for many early computer hardware and software companies.

In that community, software was freely shared among the hackers, who would build their work on the earlier programming efforts of their friends.

While the press has come to identify the term hacker with malicious individuals who break into computers over telephone lines, the hackers themselves have an earlier and different definition. A hacker, Mr. Stallman said, is one who ''acts in the spirit of creative playfulness.''

But while hacking began as intellectual sport and became a way of life in the mid-1970's, many of the hackers who had participated in the tightly knit community of computer researchers left to take advantage of lucrative employment opportunities at the new companies. Only Mr. Stallman remained behind, intent on carrying on the traditions.

The breakup of the hacker community embittered him and for several years he labored in solitude intent on the incredible task of matching the world's best programmers, writing for free the same programs they were developing on a for-profit basis at their new companies.

In his book ''Hackers,'' Steven Levy describes how during 1982 and 1983 Mr. Stallman matched the work of more than a ''dozen world-class hackers'' at Symbolics Inc., rewriting their programs and then placing them in the public domain.