Motorola Inc. and Sprint Nextel Corp. demonstrated mobile WiMax technology aboard a tour boat moving gracefully along the Chicago River Tuesday, as ecstatic designers and marketing personnel trumpeted the technology for being nearly ready to bring cheap wireless broadband to the masses.

What was demonstrated, for about 100 analysts and reporters, worked well enough. But the big questions of how much it will cost and which technologies will be disrupted by WiMax are still up the air.

As for the technology demo: Seven laptops and five wireless phones were equipped with mobile laptop gear and were able to keep constant connections to data, video or voice streams while the boat moved perhaps 5 knots, several Motorola spokesmen said.