A ROM expansion board from Rombo Productions.
The rom board has 8 rom slots which can be individually enabled using the dipswitches. A link allows the roms to use the ids of 0-7 or 8-15.
0-7 is compatible with the firmware in the 464 which is limited to 8 roms. 0-7 or 8-15 is compatible with the firmware in the 6128 and Plus.
NOTE: Some 6128's may not support ROM 7 being overridden so if you use the range 0-7 then you should disable slot 7.
Testing was done by user nrgroom on his Rombo Rom board.
The I/O port used to select the rom (dfxx) is decoded partially and only checks A13=0 like other rom boards.
ROM ids are 8-bit and fully decoded. If range 8-15 is selected with the link then you see a rom in slot '0' in 8 only. It is not show in any other slots. I.e. it's not repeated.