[Coco] CoCo2 lower graphics

[Zippster]

Yes, the XC chip is an MC6847 T1.  The pinout is different from a regular 6847.

- Ed



> On Jun 18, 2016, at 4:08 PM, Michael Pittsley <mikep at twcny.rr.com> wrote:
> 
> I'm not really sure how to respond to these messages on here.  I hope I have
> it right.  Anyhow.  Running screen0,1 goto 10 doesn't do much.  From the TV
> I have the CoCo connected to, it presents an orange line that runs up and
> down the screen until I press break.   I attempted to attach screen shots;
> however they proved to be too large to post on here. 
> 
> 
> 
> The CoCo that is having the issue has the XC80652P VDG chip (This chip is
> said to have been pre-release parts).  I reseated this chip and there was no
> difference.  I also replaced the VDG chip with a MC6847P chip from another
> CoCo.  Either these two chips are not compatible or the chip from the spare
> parts computer is also broken.  Either way replacing the chip with the one I
> had didn't resolve my issue.
> 
> 
> 
> Any suggestions will be appreciated.
> 
> 
> 
> _____________________________________________________
> 
> "Michael Pittsley" wrote:
> 
>> I have a COCO 2 that when I load certain software or cartridges the 
> 
>> bottom half the screen is garbled. [...] The garbled graphics is just 
> 
>> on some graphical games / cartridges.  If I load Tom Mix's Donkey King 
> 
>> everything works as expected.  Try to run a frogger game or Bridge 
> 
>> Tutor, I cannot see the bottom half of the screen other than gibberish
> graphics.
> 
> 
> 
> Might be worth a photo of the garbled screen.  The games otherwise seem to
> be running as expected?  Weird failure mode!
> 
> 
> 
> What happens if you type:
> 
> 
> 
> 10 SCREEN0,1
> 
> 20 GOTO20
> 
> RUN
> 
> 
> 
> ?
> 
> 
> 
> ..ciaran
> 
> 
> 
> 
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