I have an Atari 7800, but I don't think I've spent more than an hour playing on it in total - mostly because both of the controllers made for the system are simply too painful for me to use. The one that came with my Sega Mega Drive (that's Genesis to the non-Europeans I guess) is simply excellent, so I sought to find a way to use it and the schematics provided seemed easy enough - so I built this!

Assembly is fairly straightforward, but note that the metal shroud on the female connector that goes into the Atari will have to be removed in order to avoid stressing the consoles plastic ports. Also, and this is very important: the Atari 7800 controller ports don't point straight forward so you'll have to make up for it by soldering the female DSUB9 at an angle, mostly move it up until you can just about solder the pins into place (refer to the pictures for reference). Mark over at Mark Fixes Stuff also did a very good Youtube-video that shows the entire build process, perfect for those of us who are beginners at putting together these kinds of things.

Among my other shared projects, I've also put together an adapter so that the C64 JoyKEY can be used with the Atari 7800. If you're looking for a composite mod for either the Atari 2600 and the Atari 7800 those are available as well.

NB! I've tested this with wired 3-button controller and 6-button controllers - those all work great with the system. The wireless Sega Mega Drive controllers from 8bitdo, however - will not work properly with this adapter.