A quick-serve restaurant chain is testing Apple Inc.'s iPad as a customer-facing ordering and payment device, according to OrderTalk Inc., which makes online ordering systems for restaurants.

Customers at one of the chain's Boston sites, where the test is taking place, have traditionally filled out paper slips they hand to sandwich makers, said Patrick Eldon, OrderTalk's chief executive. "That was creating a lot of chaos within the restaurant environment," he said.

Eldon would not name the restaurant.

As part of the test, during busy lunch periods patrons approach an employee, who uses an iPad with an OrderTalk-designed application to enter the customer's order. The order is printed out in the kitchen. At less-busy times, the restaurant affixes the iPad to a countertop where customers can enter their own orders.

Patrons also can pay for their meals using a payment application on the iPad. Merchants set up their own merchant accounts. OrderTalk can work with several payment processors, including Chase Paymentech LLC, First Data Corp., Fifth Third Processing Solutions LLC and Mercury Payment Systems Inc., Eldon said.

The restaurant plans to introduce the iPad system at a second Boston site and at three in New York, Eldon said.