Well, the trick to the game is that you have multiple cores, each with their own register and a pipeline between them. This effectively gives you six registers, since you can bounce values back from the core on an edge register.

There are also "stack" cores, which store an arbitrary number of values and allow you to pop them back off.

If you were able to expand the system to have N cores of any type, I could easily imagine someone being able to compile C down to it.