John Sculley, whose marketing skills helped bring the personal computer to tens of millions of desktops worldwide, stepped down yesterday as chief executive of Apple Computer Inc. to focus on far broader uses for electronic technology.

Sculley will stay on as Apple's chairman. But he said his job will be to promote his vision of a world in which people have instant electronic access to a wide array of entertainment and information -- including movies, books, photographs, mail, medical records, lectures and games.

His move comes at a time when the two-decade-old personal computer industry is nearing a turning point. Many industry watchers feel that the computer is about to be merged with the telephone, television and other electronic devices to create a new breed of hybrid products and services.

Projects like those had already led Sculley -- an affable but driven man who often rises at 3 a.m. and begins work at home -- to give up day-to-day control of the company. "There is just too much for a single person to be able to do," he said yesterday. The company has grown from annual sales of $982 million to $7 billion during his tenure.

In January, Sculley made it clear how far he has moved from the Apple tiller when he showed up in the House chamber for President Clinton's State of the Union address -- and was seated next to Hillary Rodham Clinton. Articulate and carrying the swagger of an industry heavyweight, he has become a frequent lobbyist in congressional offices.

Scott McNealy, chief executive of computer maker Sun Microsystems Inc., recently did the rounds here with him. "It was kind of like being in Muhammad Ali's entourage," McNealy joked. "He knew everybody, hugged everybody, was recognized. I felt like a bag holder."

The vision Sculley and others promote foresees Americans owning a new generation of "multimedia" devices that could handle video, sound, text and graphics. The devices would be linked by a coast-to-coast network of high-capacity data circuits -- the so-called information highway.

"The real benefits of it include schools without walls, electronic libraries, finding entirely new ways of delivering health care and governmental services," Sculley told an audience of broadcasters in April. "... We'll see mass personalization, more empowerment of workers and small entrepreneurs who will be able to work with one another over the network."

Sculley has overseen development of Apple's pending offering for that market, a paperback book-sized "personal digital assistant" called the Newton. The idea is that people would carry the radio-based device everywhere, using it as portable phone, facsimile machine, scratch pad and computer.

Getting that to the market will now be the concern of Apple's new chief executive, Michael Spindler. Spindler, a 50-year-old German, was hired by Apple in 1980 to run its European operations.

A New York City native, Sculley attended private schools. He operated a ham radio and as a teenager applied -- unsuccessfully -- for a patent for a cathode ray tube he had invented. But after he graduated from Brown University, his interests turned from technology to advertising. He joined the McCann-Erickson advertising firm, then moved to Pepsi-Cola Co.

As the company's youngest-ever vice president of marketing, he honed the "Pepsi generation" ad campaign aimed at market leader Coca-Cola Co. He became the company's chief executive in 1977.

But in 1983 he made a dramatic mid-career switch, moving to Apple after its co-founder, Steve Jobs, issued a challenge now famous in Silicon Valley: "Do you want to spend the rest of your life selling sugared water or do you want a chance to change the world?"

At the time, Apple was still at an entrepreneurial stage, with Jobs creating his management style as he went along. Jobs saw in Sculley the brains and experience to bring professional management and marketing to Apple and to move computers beyond the hobbyist's den and into homes and offices en masse.

Calling on his old skills in advertising, Sculley launched the company's Macintosh computer with a whimsical Super Bowl TV ad in 1984. It likened the IBM computers then dominating the market to tools of Orwellian control.

Jobs and Sculley first communed as "soul mates." But they soon were at odds over strategy. In 1985, Sculley and the Apple board ousted Jobs in what Sculley later called "the darkest hour of my professional life." Sculley began managing the company along more conventional lines. He laid off 1,200 people, closed three factories and moved the focus of his marketing to the high-end corporate segment.

Apple's machines were commonly ranked as far in the lead in technology and ease of use. The company kept prices comparatively high and held its technology close to its chest, refusing to allow others to "clone" it.

The other companies of the industry, meanwhile, were turning to a freely available standard pioneered by International Business Machines Corp. Soon these machines were roaring ahead in power. Their software was mimicking the easy-to-use commands of the Macintosh screen.

The technology leader was left on the sidelines, accounting for about 15 percent of the market -- critics often cite this failure to win mass acceptance as the main failure of Sculley's tenure. The company remained generally profitable and managed a hit product in its PowerBook laptop computer but began looking for a new course.

In the fall of 1990, Sculley cut prices dramatically, gaining market share, and stunned the industry by entering into an alliance with its one-time prime enemy, IBM, to develop a new line of computers and software by the mid-90s.

Yesterday, Sculley denied that his decision to leave the chief executive's job was related to recent financial blips at Apple. Last week, in the midst of a computer price war, the company announced that profits would fall; that led to a 10 percent drop in its stock price in a single day. Some analysts believe Apple will have to cut its work force again to regain its buoyancy.

Asked yesterday what he sees as his accomplishments in a decade at Apple, Sculley noted the company's growth. "Today, Apple is tied with IBM for the number one position in the world and we make a lot more money than any other personal computer company in the world," he said. He noted that it had a strategy for the '90s.

He laughed off a question about the company's shortcomings on his watch, saying "you guys have been writing about that for the last 10 years."