Inside the Super Nintendo cartridges • Hacker News Board

JohnBooty wrote: post #91

hooby wrote: post #81

Earlier quoted context omitted.

noice but apparently the NES is a lot more limited, in that it wasn't really designed to accept enhancement chips. still absolutely amazing that he can run emulated SNES games on real NES hardware! but the SNES actually had that ability to accept enhancement chips - as seen in the SuperFX and others... I feel that should allow for doing drastically more!

Different set of challenges on the SNES. The NES was a little unusual in that it basically had no video ram. The PPU (the graphics chip) rendered sprites and background tiles straight off of the cartridge at 60fps as if the cartridge was an extension of the CPU's address space. So there are almost no limits to what you could do with expansion hardware, other than the fact that everything would have to ultimately be r…

The Super Game Boy cart is basically this. The cartridge contains actual Game Boy hardware, wired up to render to a frame buffer, and 60 times per second it's copied to the SNES VRAM.

The trick is that the Game Boy display is smaller than the SNES display, so it doesn't have to transfer a complete frame, and so it can be completed within the vertical blanking interval.

Apparently the timing is so close that it's not possible to transfer palette information alongside the video, just black-and-white, which is why there was never a Super Game Boy Color.