[Coco] CoCo3 PIA?

[Mike Pepe]

Mark Marlette wrote:
> james,
> 
> Where did you get the dated pricing information from? :) I was being  
> sarcastic on my $0.01 price reference. Where you? :)
> 
> If the LSTTL is not being used as the pull up and the 68x21 doesn't  
> have configurable pullups. How does the circuit guarantee a hi level  
> for the CoCo3 keyboard interface?
> 
> They also wire OR'd the joy ports in as well. Again proving that the A  
> side port must be pulled hi. What am I missing?
> 
> Mark
> 

Don't forget that in most CoCos, the keyboard uses a 6822, which as I 
recall has open drain inputs on the A port.

Check the data sheet just to be sure- just going from memory here.

My guess is that the Tandy part number PIA is just a 6822, still being 
manufactured under the Tandy part number after the 6822 was discontinued.

-Mike