Today we will modify a super sweet old school Sega Master System controller for full functionality with both the Atari 2600 and 7800.

To be honest, I really wanted to like the Atari 7800 controller. It was shaped like a coffin and looked all space-age and stuff when it came out. But after 10 minutes of using it I knew it was just another SNAFU by Atari. While Europe and the rest of the world got the super cool Atari Joypads with the 7800 release, America had to deal with these horrible POS's.

So, what options do you have? You could try and hunt down an original Joypad on eBay or you can modify one of the other plentiful compatible controllers out there to work for you instead.
Natively the Sega MS controller will work flawlessly with the Atari 2600 but due to the two button design of the Atari 7800, the pinouts are not compatible with this Sega controller. By sacrificing... (and I use that word loosely) an extra 7800 joystick we can merge the two together and build a controller worthy of the Atari ProSystem greatness! Heat up the soldering iron and lets get to it!

Step 1: Whatcha Will Need....

Since we will be merging to controllers together, all you will need is:
1. A Sega Master System controller, both model 3020 and the 3060 "control stick" work just as well.
(I found one at a local used game shop for 3 bucks)
2. A crappy Atari 7800 controller.
(oh crap I have a lot of these bastards...)
3. A soldering iron and solder
4. A de-soldering tool or de-solder braid
5. A Phillips head screwdriver
6. A Pair of wire cutters
7. Bitter frustration and hatred of the damn Atari coffin controllers.
And as always...
8. Plenty of good cold beer...
......for this project we will be consuming some New Belgium: Fat Tire.
<p>On the diagram for the Sega Control Stick you have the buttons backwards. The yellow wire should be for the Left Button/#1 and on the top hole where the picture shows the red wire. And the red wire should be for Right Button/#2 and where the yellow wire is shown. Otherwise this is great. And my controller I modded worked good other than the buttons being reversed for one game until going to the right stopped working. Probably due to my poor soldering skills. Thanks for making this.</p>
The diode was straight out of the Atari 7800 controller, so I don't know what type it is. I'm sure a standard 1N4001 would probably work, but I couldn't tell you for sure...
What kind of diode is it in the controller specifically? I'm asking because I started this a few years ago, but then dropped it and only remembered I was working on it earlier today when I rediscovered the controller and wires. I no longer have the resistors, but I know a trip to Radio Shack can fix that. I don't know about the diode, though.
why mod the controller? cant you just plug in the stock sega genesis controller into the atari and it will work?
Both the stock Sega Genesis and Master System controls will work fine on an Atari 2600 without modding. But will not work on an Atari 7800 because of the Atari 7800 controller's double fire button mapping. The 7800 controller has two separate fire buttons but, in order to be backwards conpatible with the 2600, the also need to work as a single button too.... So this mod is really just for using this controller on a Atari 7800.
ah i see, i had the master system controller but no master system and the genesis system, but i don't have any atari stuff so i was like ...isn't that over kill

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Bio: Jack of all trades, master of none, Sigh...... how does one get good at something when there are so many things in this world to ... More »
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