DALLAS - ''Good afternoon, ladies and gentlemen, you'll excuse the fact that I'm out of breath,'' the rumpled reporter gasped as he interrupted a fashion model's televised chat about the appropriateness of zippered sleeves. ''But 10 or 15 minutes ago, a tragic thing, from all indications at this point, has happened in the city of Dallas . . .'' Though he didn't know it, the reporter was bringing news not just of President Kennedy's assassination, but of a revolution in American journalism: Television, right then and there, was taking over.

Within moments of that first announcement on Dallas' ABC affiliate WFAA -- the reporter, Jay Watson, had dashed to the studio from the scene of the assassination a few blocks away, dragging witnesses along with him -- America's three broadcast television networks were, for the first time, dumping their regular programming for a breaking news story.

The soap operas, Westerns and quiz shows would not return until after Kennedy's funeral, four days and $40 million in lost commercials later. By then, 175 million Americans had tuned in to the networks' coverage for an average of 32 hours apiece.

Along with TV cameras, they had toured the sniper's nest from which the shots were fired, seen the accused assassin arrested and then murdered, visited the rotunda where the president's body lay in state, and burst into tears as his little boy saluted the flag-draped coffin. Newspapers churned out extra editions all weekend, but they were keepsakes, not news: We'd already seen it on television.

''That was the weekend that everything changed in American journalism,'' says CBS Washington correspondent Bob Schieffer, recalling Kennedy's assassination 43 years ago Wednesday. ``Up until that weekend, most people got their news from print media -- newspapers and magazines. From that weekend on, people turned to television.''