harles Simonyi, a computer scientist who joined Microsoft when it had 40 employees and who helped set its technical strategy for years, is leaving the company to found his own software start-up.

Mr. Simonyi's departure, to be announced today, will leave Microsoft with only three senior people from the team that led the company in the early 1980's: Bill Gates, a co-founder and the company's chairman; Steven A. Ballmer, the chief executive; and Jeffrey S. Raikes, a group vice president.

Unlike the other three men, Mr. Simonyi, who holds a Ph.D. in computer science from Stanford University, always worked on the technical side of the company rather than as a business manager. Mr. Simonyi, 54, held the title of chief architect for a dozen years, ending in 1999.

For the last few years, however, Mr. Simonyi has not worked on products at Microsoft. Instead, he was given the freedom to pursue a software-engineering research project — an effort he will try to refine and commercialize in his new company. His leaving Microsoft should not affect the company's current business or product development.

Mr. Simonyi's start-up, based in Bellevue, Wash., is called the Intentional Software Corporation. Its goal is to build software tools and technology to make the task of programming less complicated and more productive. These programming tools may use graphic images or charts, as well as text-based computer languages, to represent the underlying programs.

The idea, Mr. Simonyi said, is to make it easier to build and debug complex software programs by moving a step further away from conventional, close-to-the-machine coding — the painstaking handwork that can be where programmers' good ideas or intentions are lost or left out.

"We're trying to improve software productivity by making the program look more like its design," Mr. Simonyi explained.

His research had its ups and downs at Microsoft, Mr. Simonyi acknowledged. But he is being joined in founding Intentional Software by another leading researcher in software engineering, Gregor Kiczales. Mr. Kiczales, a computer scientist at the University of British Columbia, has had success applying a technology called aspect-oriented programming to make changes automatically in complex software, like sophisticated financial-transaction programs.

Other computer scientists are also working on tools to simplify programming by representing programs in ways other than in the text syntax of conventional programming languages. Researchers at the Thomas J. Watson Research Laboratory of International Business Machines in Yorktown Heights, N.Y., are pursuing the same challenge, for example, and James Gosling, creator of the Java programming language, is guiding a research project at Sun Microsystems that is trying to develop tools that present programs as graphic images instead of text.

"I think we have some important advantages," Mr. Kiczales said, "but it's not as if we are alone in this space."

Mr. Simonyi has left Microsoft with the right to use the intellectual property he developed and patented while working there. And Microsoft holds a right to be the first to negotiate with Intentional Software if the company comes up for sale.

Intentional Software will employ a handful of programmers from Mr. Simonyi's native Hungary. Mr. Simonyi left Hungary at 17 on a short-term visa and did not return, eventually making his way to the United States. He studied at the University of California at Berkeley, then Stanford, and he worked in the 1970's at the Xerox Palo Alto Research Center, where he was the principal developer of Bravo, a pioneering graphical text-editing program.

At Microsoft, which Mr. Simonyi joined in 1981, Bravo became Microsoft Word, one of the most widely used computer programs ever. And for years, Mr. Simonyi led the technical development of Microsoft's Office applications business, including Word and Excel.