The gamesystem that came to me in a dream

Alright, at the risk of sounding like a retard i am going to propose an idea to you, the Colecovision Cd. I think that it might be possible because of the expansion port in the front of the system used for other such devices as the atari 2600 adapter and the adam computer. So just tell me if i might be a little bit to blunted right now, or if this shit could at all be possible, just think Sega Cd!!!
I can't find detailed information, but it looks like it should be possible to attach a board to the port that contains a BIOS ROM, some RAM, and an ATA interface for the drive to plug into. I can't imagine a Colecovision game needing a CD though.
All I can find is a basic memory map showing where a memory or maybe multiple memories on the expansion port show up in the memory map. If I had a system or schematics to look at I could probably figure it out, but I've not seen any schematics available online.
im pretty sure that can be done are you good at digital circuits the analog part should be easy but if you did make it forget about makeing fancy games for it without modding the coleco with more memory
oh dam i did see a site that had schematics like that listed im just not sure if coleco was there (ill have to check this old HD i have laying under my bed to see it i saved it in the favoties in IE )--commodre was offcourse but maping it out yourself can be done (im sure theres only basic logic in there -- i mean thats to early for PLDs and shit

if the number are readable on the chips you can just type that in to a browser and youl get data sheets poping up for it
im sure theres only basic logic in there -- i mean thats to early for PLDs and shit

I'm told that it uses only off-the shelf parts. It's more than standard logic since it uses a TI 99xx VDP and a PSG (AY-3-8910 I think), but the address decoding is probably done with 7400 series logic.
ummmmmmm....don't we already have this in an emu port to the dc? It play fine and supports most games. Or are you just looking for a project?