[Coco] serial port problems on coco2

Aaron Banerjee spam_proof at verizon.net
Sat Jul 28 14:25:54 EDT 2012

Hmmm.  I'm not sure if this has been answered (e-mail glitch), but...

Try checking bit 0 of &HFF22 while changing the voltage of your  
"status" line (RS232IN - pin 2).  E.g.

10 GOTO 5

and then change the voltage on pin 2 of the RS232.  The number you get  
should change (e.g. from an even to odd number) based on the voltage.   
If it doesn't, there's something wrong.  My first guess would be  
either the PIA (6821) (U2 on a Coco 2, located on the "left" {away  
from cartridge connector} side of the board) or the SALT chip (U1 -  
located nearby the big power transistor).

              - Aaron

On Jul 27, 2012, at 6:26 PM, chris wrote:

> Hello list,
> Im having a problem with my main coco2 now.
> When I try and print anything the machine just hangs until I hit the  
> reset. llist also makes it hang.
> I verified that the "printer ready" high voltage is making it in to  
> the machine by testing it right on the back of the port inside the  
> computer. I hook the printer up to my 16K coco2 and it prints fine.
> Could this be a problem with one of the PIA's?
> Thanks
> -chris
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