Seems off topic, but it isn't. 
I am putting together an expansion module for the ColecoVision, using a lot of stuff familiar with MSXers. My module has a dedicated sound CPU (a second Z80) with 32KB of RAM. The main CPU can communicate with the sound CPU thru a latch port (for sending sound codes) and by taking the sound CPU bus and directly accessing the sound RAM (for loading a sound program and data).
The sound CPU will control 3 sound chips: a SCC, an YM2151 and a MSM6294 (ADPCM, four channels).
The sound CPU is already implemented in my prototype, and I have made some testing with a SCC cart I had here. I was able to play all the sounds I had created for the MSX version of Pac-Man (using SCC), as well as some Knightmare tunes taken from the MSX SCC version.
To make sure that there will be SCCs available when I decide to produce the final module, I ordered 200 SCC chips last week. And I am planning to order the remaining sound ICs later this month.
But the module is more than a sound module. It also has extra RAM memory (the CV came originally with only 1KB!) and will have a new video chip. I was considering the V9958, since it is backward compatible, but then I realized that I could be a bit bolder and go with a V9990. Well, I have a GFX9000 here, so I opened it, plugged the PCB into a connector on my prototype (which I had used previously to test the SCC) and voila! I just made a quick test and it is working. The only problem now is find out how many V9990 ICs are still around. I sent a request for quote to my chinese supplier and I am now waiting...
Well, maybe some of you remember I was programming a remake of Castlevania/Vampire Killer for the V9958 (with hardware scroll), but if I ultimately decide to go with the V9990, then I would need to create a far more sophisticated version. Since I had used the MSX2 version graphics for my V9958 remake, I thought it would be a good idea to use the X68K version as a start point for the V9990 version. So I created some mockups, which aren't completely accurate but could give me an idea about what to expect.
If all things go right, I end using the V9990 and manage to complete Castlevania Redux, the I would port the CV version for the MSX (with GFX9000). I think a 7.14MHz MSX could handle the game easily, though I would need to use the Moonsound instead the YM2151/MSM6295.
Pictures and videos bellow (the V9958 version was created with BlueMSX. Not sure why the final file is so large)…
www.opcodegames.com/download/dra.zip Castlevania Redux V9958 video
www.opcodegames.com/download/Image13.gif Castlevania Redux V9990 (mockup)
www.opcodegames.com/download/Image31.gif Castlevania Redux V9990 (mockup)
www.opcodegames.com/download/DSC01760.jpg CV expansion module prototype
Eduardo
