Famicom Mahjong controller and how does it work?

[modology]

This game called IDE YOSUKE JISSEN MAHJONG 2 comes with custom controller

https://www.ebay.com.au/itm/-/173632428 ... _cvip=true

I've been wondering how does this custom mahjong famicom controller work?
I've thought that NES/Famicom will not support any extra buttons aside from the standard buttons on standard controller?
Does it means that one could develop a game with custom controllers that provide more buttons than standard controllers?

[Memblers]

Yes, you can read more than 8 buttons. You can use an SNES controller easily, the only difference is the connector. Spookotron is one NES game that uses an SNES controller. I built the adapters that shipped with the game.

I'm not sure what's inside that Mahjong controller, but most likely it's the usual shift register chip used in NES controllers, and you can simply chain several of them together.

[tepples]

Thwaite for NES can read a Super NES Mouse through the same adapter, and the Mouse's report is 32 bits long.

[lidnariq]

We've documented this controller here: nesdevwiki:Jissen_Mahjong_controller

[Koi-Koi]

Hi.

Perhaps a strange question but how would this function, if at all, through a NES to USB or NES to Wii adapter?

I'm thinking about getting one to use in emulators.

Thanks!

[tepples]

Based on a cursory reading of the wiki page, a program running on an NES or an adapter's MCU that expects a standard controller would see this on the second expansion controller:

A: H
B: G
Select: F OR N
Start: E OR M
Up: D OR L
Down: C OR K
Left: B OR J
Right: A OR I

[Koi-Koi]

Thanks.

I think it's worth a try then.

[Pokun]

Since it can't change rows you will only get one of the two letters that Tepples listed for each button though. And you are also missing a lot of buttons, so you won't be able to play mahjong like that.