[Coco] Question about the PIA RAM Size input

Darren A. darccml at hotmail.com
Mon Apr 30 11:27:50 EDT 2007

Hi all,

Does anyone know if any harm can be done by reprogramming the Data Direction 
Register of PIA 2 such that the RAM Size input becomes an output?  Since 
this line is often jumpered to either GND or +5V, what happens when the PIA 
is trying to drive the line?

The RAM Size input is on the 'B' side of the PIA, and the 6821 datasheet 

"As outputs, these lines are compatible with standard TTL and may also be 
used as a source of at least one milliampere to directly drive the base of a 
transistor switch."


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