Mary Alice Williams; Heading the controls at New York cable news

Mary Alice Williams wanted to be a writer when she grew up . But she was a child of her times, and so, in 1968, at the age of 18, she found herself in front of a television camera, covering rock concerts, campus protests, and political conventions for KSTP-TV.

"I felt, as everybody in the business does, the power of pictures and sound," she recalls. "To me, they said more than any of us could actually put into words."

Now, 13 years later, Miss Williams stands on the newest frontier of her new frontier: cable TV. She is New York bureau chief for the Cable News Network, the first all-news 24 hour television network in the United States. Established last June, the network now boasts 753 outlets and reaches over 4 1/2 million homes in 49 states and the Virgin Islands.

Anyone walking throgh the lobby of the World Trade Center can look through plateglass windows at Miss Williams and her staff of 50 writers, reporters, producers, editors, technicians, and camera crewmen in full-scale operation. She herself designed the on-view studio that includes the open newsroom, the assignment desk over one shoulder, the production unit over another, with the monitor that brings in the satellite feed-ins, and the controller anchoring the center.

Miss Williams first came to New York in 1973 -- just a year out of Creighton University -- to become executive producer and news manager for the independent station WPIX. The following year she joined NBC as a reporter and anchor for News Center Four, where she also did investigative reporting and became the youngest woman ever to anchor a national political convention.

"New York is different from Washington, D.C.," she explains. "No news is regularly scheduled here so we have to rely on what is breaking and be able to swing fast, make instant decisions on our news priorities, and be scrappy about getting there and getting it recorded -- first. It requires enormous concentration and flexibility, and it also means that all of our people must be instant experts because they rarely have time to do much research. They have to think on the move."

About 75 percent of those people are women.

Mary Alice Williams says her network's demand is for fresh, solid information told in clear, concise language. Folksy inside chitchat by newscasters is discouraged. More precisely, for 24 hours each day the anchors offer headlines every 30 minutes, and live reports and taped packages in a blend of news and information that will keep viewers interested and informed.

Miss Williams considers the network's coverage of the hostages' return her "happiest, most moving assignment," even though it meant five 20-hour work days. Ted Turner, owner of the Cable News Network, may not share her enthusiasm; the expense of satellite broadcasting increased the ongoing deficit of his operation.

Two years ago, Miss Williams married Scott Latham, New York division manager of United Press International.

"When the news breaks," she admits a little ruefully, "we say 'Bye, Bye' and run.

Mr. Latham does the marketing and most of the cooking, chores he likes and finds both restful and interesting. The two agree they manage their home in the only feasible way, by starting the work, by each doing the necessary.

Normally they have weekends free to work on their home -- a gutted old publishing building in Greenwich Village. The construction of their airy, roomy loft quarters is now complete, but its interior decoration is not; that will have to evolve later -- side by side with the evolution of the Cable News Network.

"Our network gathers news live from where it's breaking in seven domestic bureaus, four foreign bureaus, and by way of hundreds of corresponding stations throughout the country," Miss Williams says. Already, she notes, there are 30 services transmitted by satellite to cable franchises about the country, delivering news, sports, movies, concerts, plays, children's shows, and consumer action programs.

By 1985 half the households in this country will be served by cable television. And then, if there's a newer new frontier after that? Count on Mary Alice Williams being there. She belongs to that special breed: the American front-runner.