Controller port pin 9 usage?

cr4zymanz0r

Kuroko's Training Dummy
Joined
Mar 14, 2011
Posts
73
tl;dr - On the controller ports of the Omega MVS, pins 4 (button 4 / D) and 9 are connected together. If I disconnect pin 9, will I lose any real functionality from this?


So, some pinouts seem to show button 4 (D) being connected to both pins 4 and 9 on the DB15 controller port https://old.pinouts.ru/Game/NeoGeoJoystick_pinout.shtml
I'm not aware of any superguns or DB15 style arcade sticks using pin 9 at all, and especially not for button 4. However, the Omega MVS does have button 4 connected to both pin 4 and 9.

The problem is, I found a nice Saturn to DB15 controller adapter with re-assignable buttons and other nice features that I assembled myself since it's open source and I couldn't find any in stock to buy. https://oshpark.com/shared_projects/yE8DCMIC
The adapter has DB15 pin 9 tied to reset on the microcontroller so it can be programmed from the DB15 port, so when it's plugged into the Omega MVS, when I hit button 4 then it also pulls pin 9 low as will which triggers the microcontroller to reset.

I don't really want to cut the trace on the adapter itself since I want to mess with the code myself which means I'll be reprogramming it a fair bit and it'd be annoying to be disconnect and reconnecting the trace all the time. I'm considering just disconnecting pin 9 on the controller ports in the Omega MVS itself, but I want to make sure I'm not disabling some obscure functionality that I might want later down the road.
 

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
It is safe to disconnect pin 9. The two pins were connected based on some incomplete information from way back when. It was corrected later on. It had something to do with controller type detection that snk never fully utilized.
 
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