Inside the unit, there is a backplane board mounted to the bottom of the case, that provides six interface slots that have the same number of pins and bus design as NuBus connectors.
All known Emulator SE's also have a position on this board where a Standard SNES-RF Encoding Unit could be mounted, to provide an external RF port (identical to that of the Super NES) just above the "Multi-Out" port, however no known specimens have this port installed.