Hi, I am working on useing an Arduino board to allow me to use a newer controller on my ATARI 2600 VCS. The programming should be fairly easy, but what i am worried about is the ATARI's controller circut. It is basically a bunch of push buttons, 1 for each direction (up,down,left,right) and 1 for trigger. From the ATARI schematic the push buttons are connected to ground, so i believe they are active low. I was going to use relays but I believe that is kind of a waste of power. So what I am thinking of doing now is connecting the Arduino to the 2600 's ground (common ground) and then setting a digital pin high and then bringing it low to act like the button was being pushed. In my head this should work and normally i would go right ahead and try it but i only have one ATARI right now and they are kinda hard to come by so "frying" it is not an option 
So what i am asking is if anyone else has any ideas that might work a little better? Thanks
If you are worried about sending a logic 5V into the ATARI then arrange things so that when you want the button pressed you send a logic zero to the arduino's output pin like this:-
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW);
When the button is released make it a high impedance by doing:-
pinMode(pin, INPUT);