Creating a multisystem (7800, SMS and MSX) controller?

I picked up a spare NES controller not too long ago and I also happen to have a spare Genesis controller cable laying around, so I decided to make a multiconsole controller out of them for my 7800, MSX and SMS. However, I'd like to use an external switch and trying to figure out how to wire it all up has my mind tied up in knots. Any suggestions?

 

Suggestion:

Use a system with cables and boxes, where only the cable and electronics circuity are system specific...

So, have the electronics that are system specific be part of the cable. Have the mentioned electronics box connect to the controller using a standard connection which is common to all boxes/cables.

 

Let's see...

http://www.gamesx.com/controldata/msx.htm
http://www.gamesx.com/controldata/sg1k.htm
http://www.epanorama.net/documents/joystick/tvgames.html

Basically the 7800 2-button support complicates things. If you just call it a 2600 joypad instead (SMS compatible) probably all you need is a DPDT switch on pins 8 and 9.

With 2-button support you'll need a large obscure switch, multiple switches or you can probably use diodes in a hacky way to get something working but potentially harmful. Without the console schematics in front of me I don't know what the NC pins are really connected to in the consoles so can't give much more advice.

 

Any thoughts on using DIP switches? I picked one up a few days ago but I'm still not quite sure how to go about doing this. I really don't want to use an external box as I'd like to keep this as clean as possible.

 

You're going for a small gamepad?
Gonna be tricky then unless you devise some kind of external cable+circuit system, cause I can't see much fitting in a NES pad.
And you still need different connectors.

I kinda had the same idea but I made a shmup/fightstick instead, prepared it for different systems. (as now is hardwired as genesis/megadrive 3-button). Ultimately it would house all circuitry and have the connectors attached to the housing, or yeah just doing all circitry in an external cable.

 

Not really, the MSX, 7800 and SMS all use a 9-pin connector so no worries there. All I need to do is switch around the ground pin and the second button, although the first button will need to have a switch for 7800 mode. I think I can cram all this into an NES controller, I just need to figure out how the heck this will all be wired up.

 

i've had plans for something similar only with megadrive / saturn / usb as a custom arcade style joystick

although i havnt looked into this alot

 

I managed to sketch this out yesterday and I think I've got it figured out now. I'm thinking of using two DPDT switches for pins 5-8 while pin 9 will use a SP3T switch as that pin maps to different positions between all three systems. Is 5V necessary at all for any of the three consoles? I don't plan on using the resistor and diode setup for the 7800 side of things so I don't think omitting the 5V line will cause any problems.

EDIT: Turns out I can't really fit any switches in the NES controller, shoot. Perhaps maybe I should make an arcade stick out of all this instead?