The Dynamics-powered Citi credit card lets you select which account you want to use at the time of payment.

LAS VEGAS--Dynamics' high-tech update on the old-fashioned credit card, which we covered from Demo in September, has landed a real customer.

At CES here, the company announced that Citigroup will be launching a trial of a credit card that lets users pay with either their regular credit account or with reward points they've accumulated. The user will press a button on the credit card to select a method of payment. That will activate the card's built-in electronics and rewrite the magnetic strip on the back so standard credit card-reading machines will use the chosen account.

A small number of Citi customers will get the trial Citi ThankYou Prestige 2G Card later this year

Dynamics' technology is designed to enable the creation of credit cards as thin and durable as existing passive cards, but with security features such as coded keypads that unlock the card's number display and magnetic strip, flexible multi-account features like those Citi is using, and other twists on the old, boring, static credit card.