Does anyone know where I can find information about what other typewriters had features like this? I would love to do this, and always look at the electric type

Does anyone know where I can find information about what other typewriters had features like this? I would love to do this, and always look at the electric typewriters at garage dashes, etc but have yet to find anything with a port like this. I've thought about buying one anyway and poking around the innards hopefully but that kind of thing is a little beyond my skill (and I don't own an oscilloscope).