It was fully abstracted by hardware, so no need to emulate at that level.
As for the PDP-8, the current CPU core is just a shell with nothing implemented. I've back-burnered it for the time being as there are some interesting issues associated with emulating it that I've yet to work through - namely, the modular nature of the IOB instruction.
The different peripherals for the PDP-8 actually added their own opcodes that handled certain bit configurations of the overall IOB instruction. Given the fact that ideally, these peripherals would be implemented as slot devices, it raises the question of how I would go about implementing support for them in the disassembler.