Relatedly, the PDP-11 addresses modes are post-increment and pre-decrement in order to allow programming the PDP-11 as if it were a stack machine, with a regist

Relatedly, the PDP-11 addresses modes are post-increment and pre-decrement in order to allow programming the PDP-11 as if it were a stack machine, with a register pointing at the ‘top’ of the stack (i.e. lowest address). (Reference: Computer Engineering: A DEC View of Hardware Systems Design)