[Coco] PopStar Pilot - Another chapter added

[Richard Goedeken]

I've looked at this with a scope.  I forget the exact details, but there is a 
pulse train at the beginning of an NTSC frame, and something about this pulse 
train tells the TV whether the coming field is an even field or an odd field. 
  The way that the Coco (and nearly all the old computers and game consoles) 
generate the NTSC signal, is that they always give the same field type (even 
or odd).  So the signal is like 60-hz progressive, but half of the lines are 
always dark.  In order to get true interlace, you need to set up the video 
generator to correctly generate this sync signal so that the TV will see 
alternating even and odd fields.  I don't know if the VDG/GIME is capable of this.

Richard

On 10/06/2013 12:42 AM, Nick Marentes wrote:
>  > I've not looked closely at the GIME, but it's probably just like the
>  > VDG: instead of 525 line ~30Hz interlaced, it generates 262 line ~60Hz
>  > progressive. No half lines, etc..
>
> I don't know if it's progressive. I thought all "old-school" monitors such as
> the CM-8 were interlaced. Progressive was part of VGA monitors.
>
> Correct me if I'm wrong. Anyone shed some light on this?
>
> Is the CoCo producing 30 frames per second interlaced (30 blank fields
> interlaced with active fields) or is it actually producing 60 frames progressive?
>
> Nick
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>