SD2SNES tech specs (I'd like to know ALL o'them!)

Hi guys.I'd like a deep explanation about what is inside the SD2SNES cart.
I intend to do *someday* a game to SNES and take advantage of
FPGA chip to show some cosmetical enhancements
and/or 4 split screen multiplayer modes.I was trying to develop a game to Genesis/MegaDrive using BasiegaXorz 2 years ago,
but I had to halt the project because I'm pretty busy in many subjects (studies, family, ...).I made a little search, but there are many Xilinx Spartans.
I don't understand many tech information yet and I suffered to make a
precarious tech demo of my MD mini-game.Can someone(s) help me? I'd enjoy a very long document with explanations to noobies and experts.Surely I posted this question in the EverDrive Forum, the official SD2SNES support page.
But I posted It in April 11, and 0 (zero) replies until now.
https://krikzz.com/forum/index.php?topic=6381.0
I don't know if you guys are focused on development. Any problem maybe I ask on the
BasiegaXorz forum. They solved some questions of mine, although they are a MegaDrive/Genesis forum.Thanks in advance.

I don't think anybody here would be able to answer your question unfortunately. On a related note, I once found instructions for a diy N64 flashcart but I lost them. That was based around an Altera Maxx FPGA, 64MB of EDO (I think) RAM and a couple of ISA connectors. It loaded ROMs from a PC via a parallel connection.