You don’t have to be a Nielsen family to know that TV is overrun with reruns of moldy programs from the past.

Take a quick jog around the dial and you’ll find the old crowd: Donna Reed, Hogan’s Heroes, Steve Douglas and his three sons, bewitching Samantha, the Jeffersons, and assorted cops and courtroom lawyers in skinny black ties.

Somewhere in TV’s jangled evolution, broadcasting executives decided that dredging up the old instead of creating the new was an acceptable way to fill air time. What was standard TV fare 20 or more years ago is often pap today, served up as baby-boomer nostalgia.

Other channels dipped into the well of worn-out concepts and used-up celebrities to kill the hours between their prime-time hits. Along came Morton Downey Jr.’s obnoxious tirades, packaged as social debate. Geraldo and Donahue paraded out their freaks. Professional wrestling muscled its way onto more channels, alongside the TV shopping networks and a flood of new cop shows that were just like the old — a kind of deja vu programming.

Much of what we got in the explosion of channels was more cheap and vapid TV, more channels of nothing to watch, and sore thumbs from endless search with a remote control.

How is it that TV, the technological marvel unveiled at the 1939 World’s Fair, can often seem so uninspired after being so long in the business?

In his book, “Life After Television,” George Gilder blames it on the “centralized influence” of an industry that “marched into America’s living rooms and took over for 50 years.”

Rather than creating original works, most TV writers merely “fill in the blanks of formatted shows, contriving shocks and sensations to satisfy a mass audience,” observes Gilder, who writes about technology for publications such as the Wall Street Journal, the National Review, and Forbes.

In TV’s present form, he says, thousands of writers and directors supply material for a few channels and distributors. They are paid well to imitate, not to innovate. Because only a handful of the country’s best TV and movie talents regularly have their work produced, he says, creativity suffers.

But TV’s reign as king of culture is ending, Gilder contends.

In its place, he maintains, will one day be the telecomputer, a personal computer adapted for video processing and connected by fiber-optic threads to computers around the world.

The power to process information would lie in the home computer, rather than in a broadcast station. Computers would interract with each other, tapping into a vast and diverse array of new entertainment for individual tastes. Two-way telecommunication would replace TV’s present one-way street.

Consequently, a concert could be taped with only four video cameras and transmitted to give the viewer at home a 360-degree image that could be shaped with a hand-held control.

In Gilder’s brave new “telefuture,” we could watch our children play ball at a school across the country, watch the Super Bowl from any seat in the stadium, and have our doctors make house calls without leaving their offices.

The nation’s finest teachers could produce and sell their own software for the classrooms. Home schooling would become more attractive, forcing public education to become more responsible.

Grandma would no longer be stranded in the nursing home without visitors. The whole family could drop in for a chat by way of microchips and fiber-optics running everywhere through the telephone lines. Even a millionaire anchorman like Dan Rather would discover that people don’t need him to get their news.

There could be as many channels as there are computers in the global network, Gilder says. The creator of a specialized program — fly-fishing, for instance — would be able to reach people everywhere who share his interest. The fishing-video maker could reach a large audience without the need for mass appeal, the stumbling-block of the TV industry.

“Spoiled by what was long a captive audience, however, the television networks are sitting ducks for the telecomputer,” he writes. “They will rapidly discover that many of their most successful shows quickly fail when faced with serious alternatives.”

Much of the technology exists already, he says, and the rest is developing rapidly right here in America. Local cable stations are racing to diversify their offerings.

But don’t throw away your TV sets. Gilder’s telefuture is not here yet. TV may be dying, he says, but it’s not going to give up its considerable control without a fight.

So while you’re waiting, you may want to keep checking around the dial. Who knows, next week you might even get to see “Brady Bunch — The Third Generation.”