Does anybody know how the stack really works?
I've always assumed that a push increments SP, writes on location where SPpoints at.
and a POP reads from (SP), and decrements SP, without changing the previous location pointed by SP.
i.e. a normal ram with a pointer.

but if i read out ram-contents at different positions in my program (different stack-depth) it seems that its a kind of a fifo.
i cant find anything about that in 8051 documentation.
what do i overlook?