[Coco] Coco 2 6847T1 test program

[Ron Klein]

Hi Ciaran,

I appreciate the information, sir.

My curiosity about this stemmed from an issue that was discovered with the
MC-10 driver under MAME which continued to the Coco 1 and Coco 2 drivers.
I was helping one of the MAME developers with some testing (on real
hardware) and wanted to be sure my Coco 2 was not a "B" / T1 version.  One
can always crack the case open, but I was looking for something that could
provide a visual verification through software.

Thanks!

-Ron



On Thu, Jul 20, 2017 at 2:23 AM, Ciaran Anscomb <cocomalt at 6809.org.uk>
wrote:

> Ron Klein wrote:
> > Somewhat related so for those who use MAME, there was a SG6 issue that is
> > now being addressed by one of the MAME developers.
>
> Is this where the value on the data bus is interpreted as font data?
> With bit 6 inverting as usual, so bit 6 colour ends up fixed.
>
> Used to good effect in the Dragon User published BASIC + M/C game Flee!
> (exclamation mark in title).
>
> Dragon 32 (original) and Dragon 64 ([m]) versions (not CoCo compatible)
> here:
>
> http://www.6809.org.uk/tmp/da/dragon_originals/
>
> To the original question: if it was to determine T1 presence
> programatically, I don't think you can.  The VDG doesn't provide anything
> you can explicitly read; there'd have to exist some slightly different
> side-effect (e.g., hsync timing) for it to even be possible, and I really
> doubt there are any.
>
> ..ciaran
>
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