Using AI to change game mappers

[jpx72]

Hey!
Just wondering with this new trend of recompiling games on other systems, did anyone tried to use AI to change mapper on a famicom game?
I was wondering if there finally can be a normal mapper version of Hummer team's Super Mario World.
I tried a couple chats with Claude but I lack the proper knowledge to continue on that.
Just a tought experiment

[portnoyd]

Claude can code, compile and build NES ROMs, can speak from experience. Coding is the one really strong point of LLMs. With enough prompts, I bet it could. You don't even need the background to do it really.

[UglyJoe]

Trying it out now with Codex using GPT 5.6 Sol.

Grabbed a random SMW mapper 90 rom and told it convert it to a standard mapper.

In like 15 minutes or so it gave me an MMC5 version that works in Mesen2.

Still some kinks to work out (it runs slower than with mapper 90, most notably) but I've hit my 5 hour token limit so will have to pick it back up later.

I'll have to ask it later what its loop is doing, but seems to have decompiled it, written some mapper shim, and used cc65 to compile things back together.  Runs tests using Mesen2 and lua scripts.

[fcgamer]

It works, but it really depends on what you are doing as well. Some things are quite easy to convert, others you start having to craw in the weeds.

[P]

If you share it just make sure to say that it was vibe coded.

[UglyJoe]

I haven't touched it again.  I was mostly just curious what it would do if I asked it. 

At this point, don't flash carts already support pirate mappers?  Seems like a solution to a problem that is already solved.

[P]

Yes even the old Everdrive that I have supports iNES mapper #90 and the new Pro supports even more mappers including NES 2.0 mapper format support.