Bregalad wrote:That's pretty much what the Super Game Boy does I guess.
Uhh, no? The Tristar NES or whatever does this, but the SGB uses the SNES PPU.
koitsu wrote:There wasn't enough bus bandwidth to do full-screen video playback.
Yeah, it would basically be like the Mega CD, only more limited. SNES is further crippled by VRAM being off-limits during screen rendering, so even heavy sprite rotation wouldn't be practical.
The only thing an add-on unit could do better than say a SuperFX/SA-1 would be CD-audio playback and lots and lots of raw data that carry those fun "loading, please wait" screens. It's further crippled because both the expansion port and PPU+APU are on the B-bus, so you have to doubly transfer all data.
MSU1 is basically everything the SNES CD could have offered, except in the cart on the A-bus, so you double your potential with direct-to-VRAM transfers. It's enough to pull off dithered 60%-fullscreen video, which is passable for animated video, but doesn't hold a candle to PSX/Saturn MPEG video.
The SNES-CD would further need a lossy video decoder to handle the 2.48MB/s throughput rate and smaller storage pool (700MB), making the 224x144x8bpp@30fps output even more pathetic. Also must keep in mind that the SPC700 can put out amazing sound already. It wouldn't be as huge a gain as it was for the Mega Drive.