[Tron smiles a little as the colors more closely match his own.] That will come in handy, being able to change your color like that.

Why? Because if you don't have a disc, you become a stray... lose your memories, yourself. It's very easy to take advantage of a program without a disc, so strays are more rounded up for their own protection.

At least they used to be. Clu's purpose is more to redesign them into his own army.