[Coco] Run of RGB2VGA boards

[CoCo Demus]

I think this CSS line was intentionally created as a way to auto-detect the
monitor and start the BASIC in either RGB or CMP mode. But I don't think
this was actually concluded.

On Sat, Sep 12, 2015 at 8:06 AM, Barry Nelson <
barry.nelson at amobiledevice.com> wrote:

> The official Tandy service manual says (which I just looked at) says…
>
> PIA IC4
> FF22
> BIT 3 = RGB Monitor sensing input   CSS
>
> But if the CM8 dis not ground the pin or otherwise apply a signal to it,
> and BASIC sets the pin as an output then it sounds like something that the
> engineers added to the hardware but was never used in software.
> Interesting… It also doesn't sound like much of anything can support it if
> BASIC sets it as an output. I don't remember seeing any code in OS9 drivers
> that read that pin either.
>
> On Sep 12, 2015, at 10:52 AM, Brett Gordon <beretta42 at gmail.com> wrote:
>
> > I always assumed it was a monitor detect.  I read two references via
> google:
> >
> > 1. The CM8 didn't connect this pin to ground.
> > 2. BASIC sets this PIA pin as an output...probably a goof. Of course,
> coco2 didnt have monitor anyway.
>
>
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