Yeah, a7 is the stack POINTER. Its 4 bytes yeah. But it points to the stack which is yeah i guess about 4000 bytes is about right. In TI's "documentation" they use "SP" for stack pointer. Is this an alternative thing to using a7 for the stack pointer? But of course most routines that use the stack have used a7 for the stack pointer so it probably wouldnt be such a good idea.