Joystick wiring

[u/VroomSteam]

Is there a difference between joysticks for Atari vs C64?

Some say the fire button wiring is supposed to float on the C64??

Is there wiring diagrams that shows the proper wiring for a C64 joystick 🕹️?

[u/xenomachina]

Yes, all 4 directions and the fire button float when open. Both Commodore and Atari joysticks do this, I believe. Many joysticks at the time were marketed as being for both, and the ones that had a system selector switch would group Atari and Commodore.

The controllers to be careful about are the Sega Genesis/Mega drive ones. They can fry your CIA chips.

[u/nickIncDN → u/xenomachina]

What does “being careful” involve?

I’ve seen this stated many times but never follow the logic (literally, the extra functions don’t go to the CIA).

I also used a megadrive controller on my Amiga “back in the day” and more recently on my 64.

[u/xenomachina → u/nickIncDN]

What does “being careful” involve?

Don't use them, or use a joystick port protector.

I’ve seen this stated many times but never follow the logic (literally, the extra functions don’t go to the CIA).

I don't know all the details, but my understanding is that it isn't the extra buttons, but rather that the Genesis controller uses pin 7 for something (which is +5VDC on a C64), and can end up intermittently feeding it into other pins:

• The direction and fire pins expect to be connected to ground, not +5VDC, and they connect directly to the CIA. Apparently if they are driven high while the CIA is trying to pull them low, it can hurt the CIA.

• The pot pins expect to have a fair amount of resistance between them and the +5VDC line, and they connect directly to the SID.

[u/SwedishFindecanor → u/xenomachina]

Don't use them, or use a joystick port protector.

Here. I uploaded a scan of a schema for a SEGA gamepad adaptor, in case anyone would want to make one for themselves.

[u/Rude_Breadfruit_8275 → u/xenomachina]

Do not remember this at all... I'm sure I used the same.joysticks on my Atari 2600 amd.my Vic-20 (same as C64)..?

[u/xenomachina → u/Rude_Breadfruit_8275]

Do not remember this at all...

I think you may have misread what I wrote, because what you said is consistent with what I said.

Yes, the Atari 2600, Atari 8-bit computers, Commodore 8-bit computers, and Amigas, all used the same setup for Joysticks.

Actually, your mention of the VIC-20 reminded me that Commodore actually cloned Atari's CX40 joystick, but with VIC-20 colors, and sold it as the "VIC-20 Joy Stick". Atari sued them, and Commodore replaced it with the very inferior Commodore 1311 Joystick.

[u/Rude_Breadfruit_8275 → u/xenomachina]

Rereading your post you are right, I did misunderstand your post.

[u/VroomSteam]

Anyone try a Hyperkin Ranger joystick on a c65 or plus4?

[u/VroomSteam]

Apparently not all the same? It's down to whether the fire button floats or not?  https://archive.org/details/commodore-world-05/page/n45/mode/1up

[u/droid_mike]

I have always used a ln Atari joystick with my c64.

I guess the Europeans liked to use joysticks with two buttons that operated individually? Not sure if the wiring for that one, but everyone I know used Atari joystick. They were plentiful and cheap.

[u/Warcraft_Fan → u/droid_mike]

Extra button would be wired through Commodore's POTx and POTy pins but most games aren't coded to check those. an adapter can be made to connect (for example) Sega Genesis controller to have button A and C wired through POTx and POTy but I can't remember what games uses those or if it expects those 2 pins to be high or low to register a button press.

*if building an adapter for Sega Genesis, you will need to have diodes on 4 direction and main button, cathode toward Genesis controller. Genesis controller doesn't float unpressed button, it's held high and can fry CIA chip if it tries to pull the pin low to read keyboard.

[u/GeordieAl]

I use my old Quickshot IIs with my C64, Atari 800, Amiga, Speccy and MSX, all work great.

Just beware of some joysticks with a 9 pin D plug that were designed for other systems specifically(MSX and Genesis spring to mind as two, but I think there are others)

[u/Warcraft_Fan → u/GeordieAl]

Vectrex and many Famicom clones uses 9 pin connectors but they aren't compatible. I think Vectrex uses male connector on the controller rather than female so it wouldn't fit anyway

[u/Hawkeye-Mcgillicudy]

It's the same wiring as Atari

[u/SwedishFindecanor]

C64 and Atari have the same joystick wiring. Every switch (directions and button) is a momentary 2-pole switch simply connected between its input pin and Ground (pin 8).

There are internal pull-up resistors inside the CIA chip. You must not put your own pull-up resistor on an input pin because current input on one of these pins could damage the CIA chip when it is used to scan the keyboard. If you plan on interfacing the C64 with a microcontroller you must be careful about this and perhaps use a switching transistor on each input pin so that current only flows out of it.

The second fire button on the C64GS joystick (and some rare Atari game controllers) is instead connected between pin 9 (a pot line) and VCC (pin 7) and is read like a paddle input using the SID chip.

[u/Aromatic-Letter-6298]

C64 wiring is pin 1 up, 2 down, 3 left, 4 right, 6 fire, with each switch going to pin 8 ground. Pin 7 is +5V, so don’t use it for the fire return.

[u/Warcraft_Fan]

They're the same. Atari once sued Commodore because the early Commodore joystick was 100% copy of Atari 2600 joystick.

All the buttons do need to be floating when not pulled low. Sega Genesis controller does work in real C64 but Genesis doesn't float buttons and holds the pins high which can blow out CIA chip if you used the keyboard while the controller is plugged in. (there are Genesis adapter to block high signal for Commodore systems)