What about a game pad for amstrad cpc?

[TotO]

It's just to understand the concept.
I will do tests to find a better solution to add that on a Y adapter.


Like I said previously... 3 fires buttons for CPC games are useless.
But I dislike to see hacked vintage hardware. So, if that can save some Megadrive pads...

[ikonsgr]

Maybe there is a way to do it using only one type of logic gates (AND, XOR, NOR etc) ,this way you will reduce the number of required ic's from 3 to 2.

[TotO]

May be.

[ikonsgr]

I think you can do it using  NAND gates only, like this:
[attach=2]
Only problem is, you have to use 5 NAND gates, and because these are usually come up in "packets of 4" e.g. 4 gates in one ic, you will again need 2 ic's! 

[TotO]

I think you can do it using  NAND gates only

Sure, it's the NAND equivalent required to be used with a HEX 2-Inputs NAND IC.

[ikonsgr]

Of course, i forgot they come up in packet of six too! 
Well then, using only this HEX NAND ic and a 3-state inverting buffer like 74LS366 you are done! 

[Munchausen]

Could also do it with a hex and gate.


FYI, looking at the pinouts for the megadrive controller here it looks like it would work normally with A = Fire 2 and select = Fire 1. Though not sure if it really needs +5V?


Making other buttons would require a bit of circuit trickery... maybe a 555 on the select pin and some logic to push B and C to Fire 1/Fire 3? I agree that it's nicer to do this in a cable/box than hacking the actual sega controllers... I still use my megadrive sometimes!


Apparently the 6 button megadrive joypads are much more complex...

[Bryce]

You could also do it with a handful of Diodes or even just add a cheap third button instead? but that's all beside the point, because no software other than a few art packages used it. And these software packages were designed to use the AMX mouse adapter. My USB AMX mouse adapter assigns the centre mouse button as fire 3 for this purpose.

Bryce.

[TotO]

Sure, the 3rd button is definitively a curiosity, more than a feature on CPC.

[sigh]

I would welcome a 2 or 3 button gamepad that worked without interfering with another players control when playing simultaneously. Would the game also need to be patched for this particular joypad in order for it to work properly? When using the megadrive pad, the keys are there but in an unusable order.

[TotO]

The Y adapter with 2 SMS gamepads need not hacks and work perfectly for two players games supporting 2 buttons or redefined keys (Ikari Warriors, BB4CPC ...), without conflict !

About the Megadrive gamepad, it need a special electronic because the signals are sent multiplexed.
It's why, you got side effects using it plugged on the CPC.
Adapters exists but only support 2 fire buttons... So, it's better to forget it w/o hacking.

[sigh]

The Y adapter with 2 SMS gamepays need not hacks and work perfectly for two players games supporting 2 buttons or redefined keys (Ikari Warriors, BB4CPC ...), without conflict !

About the Megadrive gamepad, it need a special electronic because the signals are sent multiplexed.
It's why, you got side effects using it plugged on the CPC.
Adapters exists but only support 2 fire buttons... So, it's better to forget it w/o hacking.

Where could you find this Y adapter for the SMS pads?

[TotO]

I think that nobody make it for sell. But, it's realy easy to do.
Only need to solder wires to 2 DB9 male (IN) and 1 DB9 female (OUT) connectors.
Work with all 1 fire button controllers as well as SMS and compatibles 2 fire buttons controllers.

I will post the schematics as soon as possible, here.
May cost less than 5€ to achive.

[Axelay]

The Y adapter with 2 SMS gamepads need not hacks and work perfectly for two players games supporting 2 buttons or redefined keys (Ikari Warriors, BB4CPC ...), without conflict !

How are the two pads able to avoid conflict?  The way I read this and the clash description, with the two joysticks on a single line each and their directions on the same columns, clash is basically inevitable?

[TotO]

May be, we don't speak about the same conflict type.
Sure, you will always encounter the keyboard ghost using the joystick port...

[steve]

Surely it would be unwise to write software that used the third fire button as it would not work on the plus models.

[ikonsgr]

Although amstrad cpc has 2 separate COM signals to support 2 joy ports, there is a problem when 2 signals are activated (e.g. grounded) at the same time:
Joystick Y-cables - CPCWiki
"However, the cable should also contain diodes in order to prevent conflicts between the two joysticks.For example, if Player 1 moves UP-and-RIGHT then UP and RIGHT are shortcut with each other. In result, without the diodes, Player 2 would automatically move UP-and-RIGHT whenever trying to move UP-or-RIGHT."

So to avoid any kind of conflict when use 2 joy ports, the Y adapter must have diodes on every signal:
http://cpcwiki.eu/index.php/File:Joystick.jpg

I make this kind of thing for anyone interested.
Using my Y adapter you can use 2 joysticks/game pads/mouses at the same time without any conflict at all! 

[TotO]

So, here a schematic concept for using 2 SMS controllers to a CPC.

[ikonsgr]

You just cut pin 5 (actually i don't connect it either, at my Y adapter, fire 3 is practically useless anyway) and redirect pin 9 of both SMS ports through diodes, to pin 7 of amstrad joy port, right? 
Well, i can surely make some of these, for those of you who might need it, but don't want to bother making it yourself 

[TotO]

I have done what I said on the previous page, but adding the diodes like you suggest. (untested)
And yes, I put the parts at the same place than your link, so most peoples can understand the change.

I think that, if you can built it for interested guys who wants to use SMS controllers, it will be nice.
(may be, the buttons need to be swapped to match with FIRE1 on left and FIRE2 on right)

[grouik1er]

Megadrive/genesis 6 button schema explained here

https://www.raspberryfield.life/2019/03/25/sega-mega-drive-genesis-6-button-xyz-controller/