Can u read 2 buttons of the 7800 in 2600 mode?

[Mot]

Can you read both buttons of the 7800 controller in 2600 mode?

 

I was just wandering because then I would like to play Booster Grip games on my CC2 with-out making a special/Colecovision controller and putting in a new controller for those games.

 

This would require code changes I know.

[Viso]

From what I can tell, it looks like it is made so that 2600 games cannot use the dual 7800 buttons. Enabling those buttons is done with output the 6532 chip found in both the 2600 and 7800, so if a 2600 game could use the dual buttons, it probably wouldn't mean to since it would have no effect when the game is run on a 2600. That would have made for a bad compatibility issue.

 

If you're considering changing the games' code, here's an idea: see if you can make it into a 7800 game. I remember seeing that there are safegaurds to prevent a 2600 game from enabling the Maria chip, but there may be no similar safeguard against a 7800 game that wants to disable it in favor of the TIA. Probably not quite that simple and I don't know that it can be done, but its the best solution I can think of short of changing controllers.

[Mot]

Ya, I thought it would be too good to be true.

 

I was thinking if it was something simple like looking at a different address/different value for button 2 then it would be very easy to change the program but rewrite to 7800 mode would be harder, and add the signature, and switch to TIA and then change the ports and values of the input.

[+-^CrossBow^-]

You could forget having the game be 2 player and just remap the second button to one of the directions or even the fire button from the 2nd player port couldn't you? I am not a programmer...especially for the 6502...so I don't know. But it would seem as if it should be possible?

 

We know that other 2600 games did this. Like StarGate, and Spy Hunter...

 

[Bruce Tomlin]

It should be possible to use the second button of a 7800 joystick (and maybe even the second button of a Colecovision joystick) as long as you set up the 6532 properly. No circuitry was changed inside the console to make this work, just in the joystick itself, by rigging resistors from the fire buttons to the paddle inputs.

 

In fact, exactly the same code should work for both 2600 and 7800 mode. But right now I don't know where any sample code is for doing this.

 

The real problem is that you then condemn people to using those damn Prolines if they don't have imported joypads or modded sticks/pads. I still have yet to convert a Wico stick, mostly because I'd like to find a way that works with both the 7800 and Colecovision. (I want the switch on the sticks to swap the base and stick buttons, so I can't use that as a mode control.)