“You always know it’s a big game when Keith’s there,” Joe Paterno, the Penn State coach, once said.
Mr. Jackson had the same reputation among his colleagues in the booth. As the former quarterback Bob Griese, Mr. Jackson’s color commentator for many years, recalled: “At our first game, he said to me, ‘All right, what do you want to do?’ I said: ‘You’re the guy who’s been here. You’re Mr. College Football.’”
Even after decades in the job, Mr. Jackson retained an old-fashioned, wide-eyed love for the college game.
“The N.C.A.A. can make anybody cynical,” Mr. Jackson once told Sports Illustrated. “But I’m not. It’s still fun to see new generations enjoy the game peaceably. I get there an hour and a half before the game and watch the bands rehearse, the people carry on. You let it seep into you.”
The National Sportscasters and Sportswriters Association, now known as the National Sports Media Association, named Mr. Jackson sportscaster of the year five consecutive times, from 1972 to 1976.
Mr. Jackson once told The New York Times how the broadcaster Ted Husing inspired his breezy style, advising him: “Never be afraid to turn a phrase. If you can say something in such a way that’s explanatory, has flavor and people can understand it, try it. If it means quoting Shakespeare or Goethe, do it.’’
He was more partial to the lingo of his native rural South.
Mr. Jackson’s “Whoa, Nellie!” punctuating an exciting play was his best-remembered good ol’ boy touch, though he maintained that he didn’t use it all that often.
He said he had a mule named Pearl while growing up on a Georgia farm but attributed the expression to his great-grandfather Jefferson Davis Robison, who evidently plowed many a field holding the reins of a mule.
“He was a farmer and he was a whistler,” Mr. Jackson told The Los Angeles Times in 2013. “He loved two phrases: ‘Dad gummit’ and the other was ‘Whoa Nellie.’”
Mr. Jackson informally christened the University of Michigan’s cavernous stadium at Ann Arbor “the Big House”; he relished broadcasting the Rose Bowl game, “the granddaddy of ’em all”; and he admired the enormous linemen, who were “the Big Uglies in the trenches.”
Keith Max Jackson was born on Oct. 18, 1928, in the western Georgia town of Roopville, and he grew up nearby, just outside Carrollton.
He joined the Marines as a teenager, then attended Washington State University in Pullman, Wash., receiving a degree in broadcast journalism in 1954. Mr. Jackson spent 10 years at the ABC affiliate KOMO in Seattle in news, sports and production, became sports director of ABC Radio West, then began broadcasting college football for ABC Sports in 1966.
When ABC’s “Monday Night Football” was introduced by Roone Arledge in 1970, Mr. Jackson was named the play-by-play broadcaster to work alongside Howard Cosell and Don Meredith, but a year later Mr. Arledge replaced him with a glamorous name, the former Giants star Frank Gifford.
Mr. Jackson returned to broadcasting college football and teamed with Bill Russell on N.B.A. games.
Mr. Jackson was considered well prepared and accurate, but amid the plaudits he was also remembered for a tumultuous moment’s action that he missed.
It happened at the December 1978 Gator Bowl game between Ohio State and Clemson.
With about two minutes remaining and Clemson leading, 17-15, a Tigers player, Charlie Bauman, intercepted a pass and went out of bounds in front of the Ohio State bench. Woody Hayes, the Buckeyes’ coach and one of college football’s biggest names, slugged him. An ABC camera showed the blow, but neither Mr. Jackson nor his color commentator, Ara Parseghian, were looking at the monitor.
ABC showed a replay, but it was from a different camera angle and did not capture the punch. Mr. Jackson signed off at the game’s end, Clemson having run out the clock, without reporting on the punch, which was seen by millions on television. Ohio State fired Hayes the next day.
Mr. Jackson, who lived in Southern California, had planned to retire after the 1998 season, but changed his mind when ABC suggested that he concentrate on Pacific 10 games so he could remain close to home.
He continued with a largely regional schedule, then retired after broadcasting the 2006 Rose Bowl game.
Mr. Jackson is survived by his wife, Turi Ann; his children Melanie Ann, Lindsey and Christopher, and three grandchildren.
Mr. Jackson shunned controversy in his college football broadcasts.
“I’m not a journalist,” he told The Boston Globe in 1999. “It’s a simple thing. When ABC spends half a billion dollars on something, I’m not going to rip and tear it apart.”
He prided himself on being concise and loath to steal the spotlight from the players.
“This is not my stage,” he said. “The stage belongs to the athletes and coaches who play the game. People don’t throw down 1,000 bucks for a TV to hear me talk.”