Re: Commodore joystick ports

From: Daniel O'Shea (
Date: 2007-04-12 12:33:40

Daniel O'Shea wrote:
> Jim, how possible do you think it is that your existing code could also 
> be adapted to the VIC-20 or Atari paddle inputs? I'm not exactly sure 
> how their timing works, but I do know that they use 1000pF capacitors, 
> and 1M rather than 500K potentiometers... would it be as simple as 
> listening for the interval between IRQs to know which system is connected?

I found some info on the Atari 2600 paddle interface here:

...looks like the capacitor is actually 68nF, I got the 1000pF figure 
from the Computer Controller Cookbook:

which hadn't steered me wrong up until now... not sure if this is due to 
the 1.8K series resistor, which is apparently not present in all 2600's?

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