1 joystick on 2 consoles

[tuneman]

Hello!

I would like to build a setup in which I will connect two 8-bit consoles/computers (let's say an Atari 2600 and a Commodore 64) to one monitor and to one fixed joystick (an arcade joystick mounted in a piece of furniture)
The monitor has multiple inputs so that's no problem.
I would like to wire the joystick as follows:
1) connect one end of all joystick switches (up/down/left/right/fire) to both ground pins on both joystick ports
2) connect the other end of the switches to both corresponding pins of both joystick ports (e.g. i will connect the up-switch to pin 1 of both joystick ports)

I realised that by doing this I make a direct connection between the 2 computers. Normally one of the 2 computers will be switched off, when playing on the other.

- Will this work at all ?
- Do I run the risk of destroying something when 1 computer is off ?
- Could I destroy something when both computers are turned on ?
- Any other ideas ? Maybe putting diodes in between ?

thanks in advance for any suggestions / comments !

[paigeoliver]

You could backfeed voltage to the system that is turned off and that could cause unwanted behavior.

You could use a serial port or parallel port switch to isolate the controller to the system you are using.

Something like this. https://www.ebay.com/itm/DATA-TRANSFER-SWITCH-2-PORT-DB25-PARALLEL/183268487883?hash=item2aaba732cb:g:pwIAAOSwsR9a9lmv

[Titchgamer]

As Paige said you do not want to run the risk of back feeding something.

Use a relay or a switch to isolate one from the other.