Hope this is the right place... Can you play Genesis games with a Master System Controller? I have seen stuff relating to playing Master System games with the Genesis controller, but not vice versa.
Depends on the game. The MD controller uses the same protocol as the SMS controller, except it multiplexes A, B, C, and Start onto two lines. B is muliplexed with A, and C is multiplexed with Start. On the SMS controller, B/A is mapped to I, and C/Start is mapped to II. (I think these are right, but they might be backwards...) Basically, the game will interpret pressing one of the SMS controller buttons as pressing two of the MD controller buttons. For Sonic games, this won't be a problem, but games that require use of all three buttons individually won't work too well. Also, games that specifically detect what controller is in use (e.g. Street Fighter II) will not detect an SMS controller, since the controller ID mechanism used in the MD results in a value of $F for the SMS controller (which is the same as "nothing connected").
1) Could you possibly play Battletoads? That only uses B and C. 2) How does a Genesis interpret an Atari 2600 controller? I've used one before to play Sonic 1, but I had to plug in a genesis controller first to press start on the title screen.
I think the Mega Drive detects the button on the 2600 stick as A, if I recall correctly. Stick is a standard D-Pad.
and vide versa, using MD pads on a C64 is not only possible, but preffered by me, and yes, B is "fire" so to speak.
Be careful using MD pads on a C64. Normal 2600-style joysticks keep inactive lines floating, and pull them low when a connection is made. Sega pads pull the inactive pads HIGH, and if you press a key on the C64 keyboard with an MD pad plugged in (which shares the same CIA chip as the joystick ports), then you have one source (the keyboard) pulling the lines low, and another source (the pad) pulling them high. This can cause extra strain on the CIA since it wasn't designed for two sources pulling the same line in both directions, and eventually it could cause the CIA chip to fail. Here is more information, including the steps that need to be taken to make MD pads 100% safe for C64 use (which can be done in an external extension cable, no need to modify the MD pad itself and potentially make it incompatible with an MD).
That part is good to know, I never knew there will be a bus fight going on. I'm happy I only ever used SMS controllers on my C64 ^^ You could solve the busfight issue with few series resistors on the muxer outputs, it is not ideal but it will make one side win without having negative consequences on other.
So the solution is either a- make an adapter that is basically a diode on every pin, that blocks the c64 from sending signal to the pad, b- do not press any keys while the sega pad is plugged in ?
How do you load a game from disk or tape without using the keyboard? Also some games use the f-keys for options. It's not recommended to plug/unplug controllers with the C64 on either so that's not an answer.
Carts. And I've unplugged joysticks all the time, since half the games I have work from port 1, while the other work from port 2.
The problem is that C64 is sending signal while controller is sending signal, so diodes aren't going to help...
