Bottom View
Here is the bottom of a canadian coco-3, Thanks to Gordon Frost!
A double row of square pins was soldered to the bottom of the game slot connector. A 40-pin wide ribbon cable, is installed to connect external projects to this extra game slot. Notice the crack in the plastic due to over-zealous cutting!
The IdeZilla, PocketIDE or MPIZilla can be hooked to this connector. For IdeZilla, use the second connector on the IdeZilla board.