> There are also upper bounds on the available IO space to a C program There isn't really, at least not in principle. You could use a FILE* as a tape and restr

> There are also upper bounds on the available IO space to a C program There isn't really, at least not in principle. You could use a FILE* as a tape and restrict yourself to relative fseeks. But this discussion doesn't concern itself with IO; obviously anything can in principle be made into a Turing machine by strapping enough IO to it.