Mike wrote:
Has anyone else ever made a Flash Cart for NES?
Yes, I have. You could find many references to it with a search on here for "Squeedo" (what I named it).
It was designed more for development, writing music, and listening to NSFs, and less for people who just want to play games (though it does play UNROM, CNROM, and NROM games - if they work with no nametable mirroring).
Mostly I didn't finish it because I had a lot of ambitious ideas for the firmware and PC host (it has a live link to PC - I can't stand swapping memory chips/cards repeatedly). I already had an EPROM emulator beforehand, so I tended to use that instead (less keys to press, and it's faster uploading to RAM compared to Flash). The basic functionality of the cart was finished already.
I'm actually in the process of bringing this design back and will be putting it back out in the world, hopefully. 5 years late! It's sad to have hundreds of $$ worth of parts for it, just sitting around here collecting dust.
It kind-of exists quite successfully in the form of MidiNES, but that's not a flashcart exactly and uses totally different firmware that x|k developed himself.