On certain Pepsi machines, you can view the number of each item sold, errors, and other stuff. The buttons are arranged in rows of 3 and columns of 4. If you press the buttons in the order 1, 3, 2, 4 , with one being the top-left button and 4 being the top right button, a menu will pop up. Use the first row of buttons to select an option, the second to change the option to a different option, and the third to go back.