Date   : Wed, 24 Oct 2007 15:59:29 +0100
From   : pete@... (Pete Turnbull)
Subject: OT was Re: UM1233 TV modulators...

On 24/10/2007 14:26, Anders Carlsson wrote:
> Pete Turnbull wrote:
> 
>> Normally the signal is indeed monochrome,
> 
> Is there a good reason why this is the case?

Yes, when you add the chroma information you decrease the resolution 
markedly.  The effect is quite noticeable on any decent mono composite 
monitor, which at the time were far more common than colour composite 
monitors (still are, actually).  So the default is monochrome.

None of this affects the TV or RGB outputs, of course.  Internally the 
video starts as RGB plus hsync and vsync; the sync signals are combined 
and fed alongside the RGB, all buffered, to the RGB socket. 
Separatel;y, they're all combined to give a greyscale signal that's 
buffered and output to the composite socket, and also buffered and with 
the chroma added a colour composite signal is fed to the modulator.

-- 

Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York