Actually, I might have misunderstood you. In your example, the index in the array is treated like the hash of the item you've put in there, why are we suddenly considering pointers?

In this degenerate case the "hash function" is base_address+(index*sizeof(memory_address))

Not really, the function is still f(key) = <some number>, the rest is just taking the number and mapping it to the hardware that you're on.