For more than two decades, the dream of controlling a computer with a pen has seduced and, more often than not, frustrated some of the biggest luminaries in the technology pantheon,including Bill Gates and Steve Jobs.

Now Mr Jim Marggraff, an entrepreneur with a long string of successful innovations,say he thinks he has figured out the secret of pen computing - and he has done it by playing with toys.

Mr Marggraff, a longtime executive at the toy maker LeapFrog, is the inventor behind a string of talking books,smart pens and other educational toys that have made their way into millions of American homes.

His new company, Livescribe, which he introduced last week at the D: All Things Digital technology conference in Carlsbad, California, has taken some of those technologies several steps further.

It has created an ambitious new type of pen-based computer system that, if successful, could bridge the gap between paper and the digital world and perhaps even change the way millions of people interact with the Internet.

History suggests that the challenge will not be easily overcome. The promise of computing with a pen has led to some of the best-known failures in Silicon Valley's history, including Apple's hand-held Newton, and the Go Corporation.

And while pen computing has finally gained a degree of acceptance with consumers through devices like the Palm line of personal digital assistants and tablet

PCs, those remain niche products,not the general-purpose machines that some pen computer pioneers envisioned.

Mr Marggraff is familiar with this history,and that, in part, is why he has turned the very notion of pen computing on its head.

Instead of forcing users to write with a stylus on a computer's slippery display,Livescribe put the computer inside a plump ballpoint pen that is used on paper imprinted with nearly invisible miniature dots. As a user writes, a tiny camera near the pen's tip watches those dots go by, recording what is being written.

Mr Marggraff said calling it pen computing is a misnomer. "We are creating paper-based computing," he said.

In addition to the camera, the pen,which is about the size and weight of a fat Montblanc pen, has two microphones to record sound, a speaker for playback, a small display that Mr Marggraff calls a pixel bar, and, of course, a hidden computer chip and other sophisticated electronics. It fits into a docking station, where it can upload or download programs and data files to and from a PC.

The Livescribe pen is a more advanced version of the LeapFrog Fly Pentop Computer, which itself has some impressive abilities, even if it is intended for children.

Fly users can draw a calculator on paper and make it work by tapping the keys with the pen; a speaker in the pen plays back the results. Users can also draw a piano keyboard on a piece of paper and play a tune on it.

But Mr Marggraff, who left Leap Frog to form Livescribe when the Fly hit store shelves during the 2005 holiday shopping season, has taken the technology several steps further.

He also plans to open up the technology to others, in hopes that Livescribe will attract content creators and third-party programmers who will develop many new uses for it, including some not yet envisioned by Livescribe's team of about 45 employees.

For now, Mr Marggraff plans to market the pen, which will be available in the fall for less than US$200 (S$304), to college students, and he has some very specific ideas for how they will use it.

The pen, he said, will revolutionise the way millions of students take notes.

To demonstrate, Mr Marggraff jots  down some notes while talking with a visitor. As he speaks, the digital recorder inside the pen captures his voice.

Once done, he taps the pen on a word he scribbled halfway down the page. The pen immediately begins to replay the conversation, starting from the point in time when Mr Marggraff had written that word. He then skips back and forth in the audio simply by tapping the pen on different places on the page.

Finally, he docks the pen, and uploads the notes and the audio to his laptop computer. Few people have seen the Livescribe so far, but veterans of the pen computing world say that while the technology sounds impressive, success is far from guaranteed.

"I hope the product matches the hype," said Mr Jerrold Kaplan, a co-founder of the pen computing pioneer Go in 1987. "It has to work really well. It's such a new concept, and often the execution of new concepts requires several iterations before the quality is acceptable."

Another challenge is that Livescribe is being introduced into a world where young people are spending more time typing text messages on cellphone keypads and writing less in longhand.

Mr Paul Saffo, a longtime technology forecaster who teaches at Stanford's School of Engineering, said, "Ironically,the big behaviour change may be to get this younger generation to pick up this unfamiliar instrument called the pen."

- New York Times Service