Ah OK the segments have the same address just different offsets from that address is that correct?

You mention:

"We have to put the stack in the same segment as the data because C requires the stack to be addressable"

Are symbols only "reachable" if they are within the base and limit of same memory segment then? If this was the case I would think that the code and stack must be in the same segment? Why is the data segment?

Cheers.