What Will said.
That code plays a little trick with the digital inputs and combines the four (0 or 1) inputs into a single four-digit binary number, where each digit represents one of the four digital inputs.
So the numbers you get are:
Code:
binary decimal
0000 0
0001 1
0010 2
0100 4
1000 8
If you get any other number it means the digital inputs aren't connected correctly. For instance, if the IR board isn't connected at all you will get
Code:
binary digital
1111 15
So that can help you to debug bad connections and see it on your OI display.
P.S. When you first use the OI Select button to switch to User Mode you'll see "u015" or something similar displayed for a couple of seconds. This is the Master Code version loaded on the Robot Controller.