SAN FRANCISCO — Panelists at a Monday evening (Feb. 7) panel session at the International Solid State Circuits Conference (ISSCC) here failed to agree on when the public will be able to buy a "Dick Tracy" style watch for Christmas, with estimates ranging from almost immediately to not within the next decade.

Answering such a seemingly simple question first foundered on the vagueness of the specification. And then it stumbled on the estimates of the technological barriers that have to be overcome. But a general consensus was that an energy source for powering a multifunction wrist-mounted wireless communications gizmo will be the main barrier to a successful introduction.

Eric Vittoz, chief scientist at the Centre Suisse d'Electronique et de Microelectronique SA (Neuchatel, Switzerland), and for many years a pioneer of low-power circuit implementation, played the devil's advocate.

Taking the "Dick Tracy" definition to imply a small stand-alone device, with nearly two years of autonomy, like a watch, he pointed out that the maximum available power is about 20-microwatts. Although he felt that might be sufficient for some computing applications. given current progress in increasing computation efficiency it would put dramatic limitations on the distance achievable for wireless communications.

"The technology will probably be available in two to three years," said Sven Mattison, analog system designer at Ericsson Mobile Communications AB (Lund, Sweden). He said. "The technology's almost there but application demand and infrastructure availability will determine if and when it happens."

Mattison drew on his experience as a principle developer of the Bluetooth short-range communications specification to point out that battery limitations would limit signal strength to around 0 dBm which in turn gives a 10-meter range for such a watch, and therefore makes full cellular communications almost an impossibility. But other forms of communication could be possible and attractive, he said.

"You could have pager-like applications, a watch with GPS [global positioning by satellite], and with a pico-cell network built out, authentication, and a simple personal information manager, and even non-GPS localization service," said Mattison.

The question remained what services would justify the commercial roll-out of a 10-meter pico-cell network.

But to conclude Mattison said: "Power will be the reason why a Dick Tracy watch doesn't make sense."

Wai Lee, analog design manager in the ASIC division at Texas Instruments Inc. rose to the challenge and stated boldly in his positioning statement printed in the ISSCC digest. "A 3G mobile phone in the form of a Dick Tracy watch will be available in 2004."

He chose to be optimistic and referred the audience to an MP3-player watch, a Palm-pilot watch, and a digital still camera watch, all available today.

He also showed the steep curve of increasing DSP performance which has improved, in terms of MIPS/watt by an order of magnitude every five years since 1980. "One milliwatt will give 100 to 1000 MIPS of computing power in 2005," he said.

"Let's forget about the battery. Some innovation is needed for energy sources." He then listed alternatives such as body heat, mechanical energy and even the burning of body fat or cholesterol to power body worn devices.

Yuji Kitamura, development manager at Sanyo Semiconductor Corp. (Rochelle Park, NJ) was similarly upbeat. "A cell phone and watch will become available by 2005 but a video-cellphone-watch, not in this decade."

It was left to Rein de Graaf, a system architect at Philips Semiconductor working on the company's compact personal communicator (CPC) project to draw out the panelists: that the Dick Tracy watch could and would appear soon in the form of a relatively dumb and low-power terminal interfacing wirelessly to some other less volume- and energy-constrained piece of personal electronics, such as the mobile phone.

Steve Mann, a professor at the University of Toronto, was hailed as the father of the wearable computer and the ISSCC's first virtual panelist, by moderator Woodward Yang of Harvard University (Cambridge Mass.).

Mann took part in the panel from his office in Toronto and demonstrated his "eye-tap" technology, a spectacles-mounted camera that gives his view of the world. The audience for the evening panel was able to share Mann's view of his desk as he spoke and made notes, although the data rate of a few frames a second made for difficult viewing even on the giant screens where the images were thrown.

Not surprisingly, Mann was generally upbeat at least about the technical possibilities of distributed body-worn computing, showing that he had already developed a combination wristwatch and imaging device that can send and receive video over short distances.

Meanwhile, in the debate from the floor that followed the panel discussion, ideas were thrown up, such as shoes as a mobile phone — powered by the mechanical energy of walking, and using the Dick Tracy watch as the user interface — and a more distributed model where spectacles are used to provide the visual interface; an ear piece to provide audio; and even clothing to provide a key-pad or display.