[Coco] 384 or 450 scanlines ?

[Gene Heskett]

On Monday 13 January 2014 14:44:37 Nick Marentes did opine:

> Arthur Flexser <flexser at ...> writes:
> > Thanks for the explanation, John.  I'm curious, though, about why the
> > 6847 non-interlaced VDG was chosen for the CoCo rather than the 6847Y
> > interlaced version.  And, would a 6847Y VDG work if you replaced the
> > 6847 in a CoCo with it?
> 
> And I thought that the interlacing was fixed in the TV/monitor of an
> interlaced set. That a monitor always provides 525 lines interlaced
> (NTSC).
> 
> That's why I thought the CoCo had to provide either 2 fields or 1 field
> and a blank field to satisfy the interlaced function of the monitor.
> 
> I guess it makes sense that the early video game systems and TV's would
> just create a single 262 line display that is repeated. I didn't know
> that the TV/monitor could stop creating the interlaced field.
> 
> Nick
> 
Poorly designed monitors will do it anyway Nick, by allowing hscan noise 
into the vertical sync circuits. Usually due to woefully inadequate power 
supply filtering.


Cheers, Gene
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