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From: mlelstv@medusa.informatik.uni-erlangen.de (Michael van Elst )
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech,comp.sys.amiga.hardware
Subject: Re: A3000 Video Chips
Message-ID: <3003@medusa.informatik.uni-erlangen.de>
Date: 16 Jul 90 11:08:39 GMT
References: <4741@munnari.oz.au> <13060@cbmvax.commodore.com> <16713@windy.dsir.govt.nz> <1091@mpirbn.mpifr-bonn.mpg.de> <13110@cbmvax.commodore.com>
Organization: CSD, University of Erlangen, W-Germany
Lines: 22

grr@cbmvax.commodore.com (George Robbins) writes:
>In article <1091@mpirbn.mpifr-bonn.mpg.de> p554mve@mpirbn.UUCP (Michael van Elst) writes:
>> As far as I know, neither the A2000 nor the A3000 are producing a
>> composite video signal that could contain a colour sub carrier.
>> Their output are separate R,G and B signals. The differences between
>> PAL and NTSC modes are timing differences only.

>Ah, but both machines do provide one of the ~3.58 MHz clock phases as a
>reference signal for the video slot, which might contain either a color
>encoder or some other video toy.

PAL specs don't say anything about phase relationship between sync signals
and color burst. And the color is the phase shift between color sub carrier
modulated onto the video signal and the color burst signal. I believe it's
the same in NTSC.

Of course, the video clock (~3.58MHz) can be used to generate a color
sub carrier. The C= RGB/PAL converter does this (I tried to use it with
another computer but had to add a crystal to get it to work).

Michael van Elst
p554mve@mpirbn.mpifr-bonn.mpg.de