More fun in Nintendo land!

[jeffro11]

Well I replaced a Nintendo proprietary MAD1 decoder chip with an off the shelf 74LS139... And it works! The game is Super Mario World. Everything still works perfect. Lost the save data when I removed the MAD1 since that's what controls the Battery. Well worth it though!



A little background on the mad1... It's a decoder, obviously, however it also controls the battery and the voltage to the SRAM. When there is no power the mad1 allows the battery to supply power to the SRAM chip. So by removing the mad1, obviously it will no longer function properly. So a little re wiring is needed to counter act this. The spec sheet calls for CS(pin 18) of the SRAM to be supplied with 2.2V, and VCC (pin 24) to be supplied with 3.0V.
Wiring Diagram:
Remove the MAD1... obviously.


Ziggy if you read this, I require you to attempt this on a HiRom cart. I will be doing the same.

[slowslow325]

I don't know much about electronics, but what exactly did this accomplish? Did it do something cool, or was it just for show?

[jeffro11]

It proves that it can be done. The same will be applied to a game that uses HiRom so we can get a schematic for a base universal reproduction cart. Instead of using donor boards, we will have our own boards created.

[Ziggy]

Jeffro, did you confirm that the cart still saves?

I'm very excited about this!

[jeffro11]

The cart still saves with some minor rewiring.

[jeffro11]

Updated the first post with the diagram if anyone wants to try this.

[jeffro11]

Another update; I have successfully used a HiRom to do this conversion on, all I need to test out next will be a CIC clone. After that then the snes repro board project will commence!

[Ziggy]

This is awesome, SNES repro boards are 100% possible now. I'm very excited! The designing will be fun, I'm still worried about production though.

[Satoshi_Matrix]

wow I can't believe nobody has said this yet.


U MAD1?