RE: Commodore joystick ports

From: Scott McDonnell (
Date: 2007-04-09 05:31:17

> -----Original Message-----
> From: 
> [] On Behalf Of Jim Brain
> Sent: Sunday, April 08, 2007 10:21 PM
> To:
> Subject: Re: Commodore joystick ports
> It wasn;t your post I was referring.  Someone (Pasi?) 
> suggested the 512 
> might be to allow the internal circuitry to be multiplexed, 256 for 
> POTY, 256 for POTX.  However, if that were true, I reasoned 
> you should 
> see the drive to zero trigger alternate, and it does not.

Ah. I must have missed that. My mistake. Definitely unlikely.
> Given the low sample rates involved and the target (paddle 
> input), your 
> position is correct.  However, Jeri is known for trying to 
> deal with the 
> minutiae.  As well, using a regular ADC would no doubt 
> preclude the use 
> of the 1351 mouse, which depends on the 512 cycle period.

Very true. At least on the hummer, there is an external ADC. According
to info found on the net, it is actually a Successive Approximation ADC
similar to the SNAD01C. It is located on 3 pins of the user port. Not
much compatibility with the 1351.

> > Again, yours and Levente's methods both work as you both have 
> > demonstrated. Nobody is questioning that, of course. But, I am just
> >   
> I'm not defending it per se.  I had a hammer (uC) for other 
> reasons in 
> my project, so I manufactured the "nail" to make it all work.
> It's OK, though.  Someone asked me to delve into more details 
> on how the 
> PSXJoy emulates the paddles, and I admit I had forgotten a 
> lot of this 
> since late 2004, so it was a good refresher.
> Jim

Good. Just wanted to be sure we weren't getting into a debate over this.

That wasn't my intention.

Scott McDonnell

       Message was sent through the cbm-hackers mailing list

Archive generated by hypermail pre-2.1.8.