Calindro wrote
On SMS, all even ports between $C0-$FE read from the first I/O port, all odd ports between $C1-$FF read from the second I/O port.
On MD, only $C0 and $DC work for the first port and $C1 and $DD for the second port.
Oh wow! That's interesting. I wonder why MEKA acted the same way as my Genesis model 2 then. I'm getting a real SMS shortly, so hopefully I'll be able to start testing on that soon!
Sort of off topic, but do you know why some games (Like Alien Syndrome) only work with the SMS controller? Is that more of a hardware/voltage related thing?