John R. Opel, who presided over I.B.M. in its final period of dominance in the information-processing industry and oversaw the company’s move into personal computers, died on Thursday in Fort Myers, Fla. He was 86.

His death was confirmed by Jeff Wickham, a son-in-law, who declined to disclose the cause.

Mr. Opel (pronounced OH-pel) joined I.B.M. as a salesman in 1949, as the computer age was just dawning, and served as the company’s chief executive from January 1981 until January 1985.

A year after he took the top post, the Department of Justice dropped its 13-year-old antitrust lawsuit against I.B.M., freeing the company to compete more aggressively.

Compete it did. Revenue nearly doubled during Mr. Opel’s tenure, to the point that by the end of it, competitors were publicly complaining that I.B.M. was too powerful. In 1983, Time magazine featured Mr. Opel on its cover with the headline “The Colossus That Works.”