How can a program physically leave the Grid in Tron: Legacy?

I'm sure someone has thought to ask this before, but I couldn't find it. In Tron: Legacy , the end of the film sees our hero Sam

How is this possible? As I understand it, an ISO is merely a program-based lifeform that evolved spontaneously rather than being written by a User. And CLU is esentially just a super-powerful AI built to run the TRON world. However, no matter how advanced the AI behind a program is, it's still just a program that exists as code in the computer. There's no body to digitize, and no other known way to contain the code in the real world.

How is it possible for any program to leave the Grid and enter the real world?