“A restaurant is the only remaining place in the retail economy where the card disappears, where you actually hand it over and the transaction is not processed right in front of you,” he said. “There is an opportunity for it to be copied and skimmed.”

Image TIME SAVER At Four Food Studio in Melville, N.Y., a customer signs his check while the waitress stands by, holding a portable credit card processor. Credit... Maxine Hicks for The New York Times

Those who have used the systems in Europe may wonder why it has taken so long for them to show up here.

Henry Helgeson, the president of Merchant Warehouse in Boston, which sells credit card systems, said restaurant owners are typically cautious. “They’re waiting to see if it works before they make a big leap,” he said.

A number of midprice restaurant chains are experimenting with them, a process that can take months. On Long Island, Four Food Studio in Melville has been using the system for about a month. They have four units for 13 waiters and plan to add more.

“Our guests say it gives them peace of mind, being able to pay the check without giving up their credit cards so there is no opportunity for fraud and identity theft,” said Jay Grossman, one of the owners. “It speeds thing up, too. There has been complete acceptance; after all, we’re in the world of BlackBerrys and iPods.”

Roger Berkowitz, the president of Legal Sea Foods, which has more than 30 restaurants along the East Coast, has been using the equipment in some of his restaurants for about a year.

“It takes training but it doesn’t take long for people to be comfortable with it,” he said.

Mr. Drummond of Ingenico said that pay-at-table represented a “cultural shift,” with restaurateurs fearing that using the devices may appear to rush the customer. Some owners of high-end restaurants in New York seemed wary. Drew Nieporent, an owner of the Myriad Restaurant Group, said he thought the gadgets were not “classy.”