Comcast Corp. chief executive officer Brian Roberts dazzled a cable industry audience Tuesday with the first public showing of technology that enabled a data download speed of 150 megabits per second, or roughly 25 times faster than today's standard cable modems.

The cost of modems that would support the technology, called "channel bonding," is "not that dissimilar to modems today," he said after a demonstration at The Cable Show in Las Vegas. It could be available "within less than a couple years," he said.

The technology, called DOCSIS 3.0, was developed by the cable industry's research arm, Cable Television Laboratories. It bonds together four cable lines but is capable of allowing much more capacity. The laboratory said last month it expected manufacturers to begin submitting modems for certification under the standard by the end of the year.

In the presentation, ARRIS Group Inc. chief executive Robert Stanzione downloaded a 30-second, 300-megabyte television commercial in a few seconds and watched it long before a standard modem worked through an estimated download time of 16 minutes. Stanzione also downloaded the 32-volume Encyclopaedia Britannica 2007 and Merriam-Webster's visual dictionary in less than four minutes, when it would have taken a standard modem three hours and 12 minutes.

"If you look at what just happened, 55 million words, 100,000 articles, more than 22,000 pictures, maps and more than 400 video clips," Roberts said. "The same download on dial-up would have taken two weeks."

Brian Dietz, spokesman for the conference host, the U.S. National Cable and Telecommunications Association, said the demonstration was the key technological advance showcased at the conference.

"It's an exponential step forward and we're very excited. What consumers actually do with all this speed is up to the imagination of the entrepreneurs of tomorrow."