Two controllers on the same port?

[Pixelboy]

Here's a simple question for ColecoVision hardware experts: Would it be theoretically possible to have some sort of adaptor that would allow two controllers to be plugged into the same joystick port on the CV console? Kinda like the original paddle controllers on the Atari 2600. Could the CV console cope with such a dual input scheme?

 

Just curious.

[+5-11under]

I think I described this in a "what homebrew would you like to see next" thread, where I said I'd like a 4 player game. Sure, this can be done, and fairly easily, I think. Getting the keypad to mesh between two players wouldn't work too well, I think, but you could fairly easily split the directions and the two fire buttons, I think. One player could have left and right and fire1, while another player could have up and down and fire2 (re-wired to play like the first player, of course). You could verify with Classic's controller test, to make sure you have full control of each of both fire buttons at the same time... I think you do. Same with the keypad and fire 3/4... there might be a few cases where you could split them between two players (haven't tried all the combinations, to see if any work separately from eachother - without screwing up the output - like when you press to keypad buttons at once and get a different result).

Edited March 2, 2011 by 5-11under

[Pixelboy]

I think I described this in a "what homebrew would you like to see next" thread, where I said I'd like a 4 player game. Sure, this can be done, and fairly easily, I think. Getting the keypad to mesh between two players wouldn't work too well, I think, but you could fairly easily split the directions and the two fire buttons, I think. One player could have left and right and fire1, while another player could have up and down and fire2 (re-wired to play like the first player, of course). You could verify with Classic's controller test, to make sure you have full control of each of both fire buttons at the same time... I think you do. Same with the keypad and fire 3/4... there might be a few cases where you could split them between two players (haven't tried all the combinations, to see if any work separately from eachother - without screwing up the output - like when you press to keypad buttons at once and get a different result).

Interesting...

 

So you'd have only two directions on the joystick, per player? Couldn't the keypads be "rewired" so that all four directions on both joysticks could be used, even if it means losing the keypads entirely (no big loss there)?

 

EDIT: By "rewiring", I mean having the two missing directions on the joystick mapped to keypad keys.

Edited March 2, 2011 by Pixelboy

[+5-11under]

What you need to try is to go into Classic's controller test, for instance, and see what different keypad and fire2/3/4 buttons are distinct from each other. What you don't want is to have player one press the 1 on the keypad (for whatever purpose) and player two press the 9 on the keypad (for whatever purpose), because I think you'd end up thinking the * was pressed. That's workable to some degree... but you wouldn't want to have the * key by itself (because it really means 1 and 9 are pressed).

 

Also, for the extra functionality of keypad buttons, you might need to have custom-wired controllers. Not sure about access to fire2.

[Pixelboy]

What you need to try is to go into Classic's controller test, for instance, and see what different keypad and fire2/3/4 buttons are distinct from each other. What you don't want is to have player one press the 1 on the keypad (for whatever purpose) and player two press the 9 on the keypad (for whatever purpose), because I think you'd end up thinking the * was pressed. That's workable to some degree... but you wouldn't want to have the * key by itself (because it really means 1 and 9 are pressed).

 

Also, for the extra functionality of keypad buttons, you might need to have custom-wired controllers. Not sure about access to fire2.

Okay, let's see if I'm getting this right... For example, all four directions on player 1's joystick could be mapped normally, but for player 2, the four joystick directions could be remapped to keypad keys (via the adaptor) and it would be up to the game program to make sense of it all?

[+5-11under]

Someone feel free to correct me if I'm wrong, but one way would be to have two controllers basically in parallel, except:

 

Player A has pins 1 and 2 of the DB-9 connector cut, and Player B has pins 3 and 4 of the DB-9 cut (or re-routed to pins 1 and 2) (I think I got that right), so left and right work for both (although the CV will register Player B as up and down). The hard part comes with the fire buttons, because you can't just cut pin 8 out of one of the DB-9s. You could cut pin 5 of one controller, losing the keypad functionality. Sorry, thinking out loud mostly... you'd probably need to re-wire or create a new joystick with custom wiring to get player B to have a distinct fire button.

 

Here's the schematic, although I think the keypad diodes are shown backwards (it all gets too confusing ): http://www.atarihq.com/danb/files/ColecoController.pdf

[Pixelboy]

Here's the schematic, although I think the keypad diodes are shown backwards (it all gets too confusing ): http://www.atarihq.com/danb/files/ColecoController.pdf

I'm far from being an expert at reading such schematics, but isn't it diodes D14, D28, D21 and D6 that are reversed? That would be the case if pins 1, 2, 3 and 4 are output pins...

 

Even if what I say is correct, I don't quite understand how it works electronically...

[youki]

Funny, i talked about that with Yurkie few weeks ago for a future project.