Some revolutionaries hear a different drummer. Karen Fries listened to a man rave about a duck.

The Microsoft Corp. program manager was showing a novice personal-computer user some prototype software to test concepts for making PCs easier to use. A cartoon duck appeared in one sequence.

``This guy was very emotional about it _ he grabbed my arm,'' Ms. Fries recalls. ``He said, `Save all the money on the manuals, and just give me this duck to always be there and tell me what to do.'''

Three years later, the software industry's dominant force is heading in that radical direction, largely because of the persistence of Ms. Fries and her partner on the project. They led the development of Bob, a suite of eight programs for automating household tasks that use animated characters to give instructional tips. The software, identified by a happy face logo with glasses, was introduced last week at the Consumer Electronics show.

Cutesy characters have been tried unsuccessfully before. ``It is patronizing to the user,'' argues Ben Shneiderman, a University of Maryland computer science professor who is an expert in the field. ``Maybe it's cute the first time, but it's silly the second time and an annoying distraction the third time.''

But the underlying concept, in which computers help users by prompting them with questions, is gaining wide support in an accelerating movement to change the way software is designed. Apple Computer Inc. plans to use such dialogues in operating systems, code-named Copland and Gershwin, that are scheduled to be released in 1996 and 1997, says Don Norman, who heads Apple's research in the field. Now he is using Bob to prod senior management to get the new concepts to market sooner.

``The impact of Bob will be more than whatever it sells,'' predicts William Gates, Microsoft's chairman and chief executive officer. ``The idea of a social interface as pioneered here will become pervasive.''

If so, it won't be because Mr. Gates or his lieutenants had the idea. Indeed, Bob is a classic victory of low-level zealots in technology's trenches. Ms. Fries, who is 30 years old, faced an exhausting struggle to win resources to develop the program, a diversion from Microsoft's single-minded promotion of its Windows operating system.

The 20-year-old company harbors many whiz kids who started writing computer code in their teens. They compete fiercely for management attention and the Holy Grail of ``head count,'' the staffing level that determines whether or when programs reach the market.

Ms. Fries, whose name is pronounced ``freeze,'' is no code jockey. She studied business and psychology in college before joining Microsoft seven years ago as a personnel recruiter. But tech talk comes naturally. Ms. Fries's two brothers also work in product development at Microsoft; her father is an engineer at Boeing Co., and her mother is a consultant who used to work for Digital Equipment Corp.

Associates say Ms. Fries is pleasant to work with but pushy about her cause _ PC users and their problems. When Mr. Gates was set to show off Bob at a company meeting last summer, Ms. Fries insisted on an extraordinary 20 minutes to make her presentation. She was offered five and wound up taking about 10.

``The idea of a social interface did not catch on immediately at Microsoft,'' says Clifford Nass, a Stanford University communications professor who became a consultant on the project. ``Her passion pulled a lot of people along until they had the resources to carry it off.''

Ms. Fries made her name in product development with Microsoft Publisher. The low-end desktop program, Microsoft's first to engage users in rudimentary questions about what they want to accomplish, started her collaboration with Barry Linnett, a seasoned designer who became her partner on Bob.

Publisher was relatively easy to use, but the two weren't satisfied. After completing the project in September 1990, Ms. Fries and Mr. Linnett began intensive sessions in Microsoft's usability lab, where PC users are studied from behind one-way glass.

The sessions _ which included the duck episode _ provided ammunition for a heretical memo in January 1991 that attacked Publisher as too hard to use. They used the memo to get an audience with Mr. Gates and lobby for personnel. ``We asked for 35, and Bill gave us three,'' Ms. Fries says.

Mr. Gates says their ideas were intriguing, but he pushed them to come up with specific tasks a new product could do and evidence they could pull it off. ``It was frustrating at the time,'' Ms. Fries says. ``I would say we were naive.''

MORE