Possible to use Atari / C64 stuff?

[odin]

Yup, they all have the same 9-pin connector. Joysticks will work a treat on all three platforms. Mice however are a bit different; Atari mice need to have 2 pins swapped for them to be usable on an Amiga. A lot of 3rd party mice of that Amiga/Atari era have a switch on the bottom to select Atari or  Amiga.

Dunno if {bleep} like lightpens/guns etc will work though.

[odin]

Makes sense, I'd hazard a guess that these beauties:

were one of the first mass produced joysticks :-). Ah great joysticks those were, if you forget the blisters and the failing hi-tech metal 'bubble' switches ;-).