@charliefrown, post #1
@charliefrown, post #1
@teh_KaiN, post #4
@madman15, post #7
@sanjyuubi, post #6
@Tom Rain, post #11
@BULI, post #13
Master System and Mega Drive controllers are compatible in Amiga, but at the same time they are not. Let me explain...
Amiga power the joysticks with pin 7 and Sega power on pin 5. So why does the Sega pads work on Amiga? The answer is that Amiga also have a +5 voltage on pin 5. This pin is used for steering wheels and such. It's essentially reading an analogue signal like the PC gameport (do you remember those?). You can not draw as much current from pin 5 as you can from pin 7. Maybe this is the reason why some people have blown the CIA?
What happens when a Mega Drive drive controller is connected to an Amiga is that the Amiga power pin 7 is acting as the Select signal for Mega Drive and will output button B and C as Amiga button 1 and 2.
What you should do to do things right is to open the Sega controller and swap the wires so the controller is powered from pin 7 instead.