Ken Olsen, who helped reshape the computer industry as a founder of the Digital Equipment Corporation, at one time the world’s second-largest computer company, died on Sunday. He was 84.

His family announced the death but declined to provide further details. He had recently lived with a daughter in Indiana and had been a longtime resident of Lincoln, Mass.

Mr. Olsen, who was proclaimed “America’s most successful entrepreneur” by Fortune magazine in 1986, built Digital on $70,000 in seed money, founding it with a partner in 1957 in the small Boston suburb of Maynard, Mass. With Mr. Olsen as its chief executive, it grew to employ more than 120,000 people at operations in more than 95 countries, surpassed in size only by I.B.M.

At its peak, in the late 1980s, Digital had $14 billion in sales and ranked among the most profitable companies in the nation.