sanni:
I don't know exactly why this fixed it but I updated the code on github anyway.
The added slot on the design idea I posted is a NES slot but ofc there is no code written for it.
Oh wow, I'm surprised you added an NES slot to the cart reader sanni.
Just wondering if you're working on code for it? I think I remember seeing another device which can backup/restore NES saves, although I believe it's in the beta stage (as tempting as it is to buy this device, I think I'm gonna stick with the Arduino). I'm looking forward to hearing more news about the new NES slot in the future.