I've been thinking about this for awhile. I know that it would be impossible to make an universal NES cart and this has nothing to do with that.
I mean like combining to mapper chips onto one board and using certain functions sepereatly (by connecting the certain pins to the areas they need to be connected to so that they can do those certain funcions only). Now this is just me rambling and it's just a thought I couldn't get out of my head. I mean of course you need to know the pinout of each chip and need to know the exact pins that need to be connected to the exact place to get it all working, but still it would be very interesting you know ^__^
Just want to know if it's even possible. Any info would help. thx :-)