[Coco] is there any existing 6847 output to RGB ? (for coco2)

[didier derny]

Finally I have an explanation on the use of 525 lines chip on a 625 line tv

http://users.on.net/~clockmeister/VZ300/VZ300-tech-ref-man.pdf

check page 6, they are doing a 525 lines to 625 lines conversion
the same way as on the Alice (and probably the mc 10 PAL)

this conversion is done by the chips  Z18/Z19/Z20

this information comes from mc10/alice lovers on a French forum

--
didier


-----Message d'origine-----
De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de Zippster
Envoyé : jeudi 19 février 2015 22:13
À : CoCoList for Color Computer Enthusiasts
Objet : Re: [Coco] is there any existing 6847 output to RGB ? (for coco2)

Probably "close enough”.  Does it say anywhere in the files you found what ic Z20 is?
Weird way to run a clock to the 6847.

- Ed


> On Feb 19, 2015, at 3:02 PM, didier derny <didier at aida.org> wrote:
> 
> Btw apparently on the alice the clock is not 3.5795... but 3.55
> 
> -----Message d'origine-----
> De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de Zippster 
> Envoyé : jeudi 19 février 2015 21:54 À : CoCoList for Color Computer 
> Enthusiasts Objet : Re: [Coco] is there any existing 6847 output to 
> RGB ? (for coco2)
> 
> Not familiar with the SECAM standard, but the flip-flop is clearly used to adjust the sync.
> 
> - Ed
> 
> 
>> On Feb 19, 2015, at 2:50 PM, didier derny <didier at aida.org> wrote:
>> 
>> When this machine was sold, it was not so common to find a TV with 
>> PAL Most were only SECAM, PAL+SECAM were really expensive
>> 
>> Later PAL+SECAM TV around 1990 where very common
>> 
>> 
>> 
>> -----Message d'origine-----
>> De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de Luis 
>> Antoniosi (CoCoDemus) Envoyé : jeudi 19 février 2015 21:43 À :
>> CoCoList for Color Computer Enthusiasts Objet : Re: [Coco] is there 
>> any existing 6847 output to RGB ? (for coco2)
>> 
>> It's flip-flop. It must be used to convert the NTSC sync to PAL sync.
>> 
>> 
>> Luis Felipe Antoniosi
>> 
>> 
>> 
>> On Thu, Feb 19, 2015 at 3:36 PM, didier derny <didier at aida.org> wrote:
>> 
>>> The schematics I discovered:  http://6809.eu/schema_alice4k.png
>>> The mc10 schematics:          http://6809.eu/schema_mc10.png
>>> 
>>> --
>>> didier
>>> 
>>> -----Message d'origine-----
>>> De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de 
>>> Zippster Envoyé : jeudi 19 février 2015 21:28 À : CoCoList for Color 
>>> Computer Enthusiasts Objet : Re: [Coco] is there any existing 6847 
>>> output to RGB ? (for coco2)
>>> 
>>> Yes, if it’s just a bunch of transistors (no comparators or adc) 
>>> then it must be mixing the component signals to RGB while keeping it all analog.
>>> 
>>> I’m working on one (Digitize —> RGB —> DAC —> VGA) but have a way to 
>>> go yet.
>>> 
>>> - Ed
>>> 
>>> 
>>>> On Feb 19, 2015, at 2:16 PM, Luis Antoniosi (CoCoDemus) <
>>> retrocanada76 at gmail.com> wrote:
>>>> 
>>>> Well I do have a coco2 peritel with a RGB output for SCART TVs. It 
>>>> does everything on transistors, actually a transistor plantation...
>>>> 
>>>> I think it does a YCbCr -> RGB conversion. The VDG outputs YCbCr.
>>>> 
>>>> 
>>>> Luis Felipe Antoniosi
>>>> 
>>>> 
>>>> 
>>>> On Thu, Feb 19, 2015 at 3:04 PM, didier derny <didier at aida.org> wrote:
>>>> 
>>>>> Is there any existing 6847 output to  rgb board / schematics
>>>>> 
>>>>> 
>>>>> 
>>>>> I've just seen the pinout of a RGB video connector
>>>>> 
>>>>> But the video in the machine is done by a 6847
>>>>> 
>>>>> 
>>>>> 
>>>>> The schematics are hard to read  and there are a lot of 
>>>>> transistors
>>>>> 
>>>>> Between the video signal on the 6847 and the connector.
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> --
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>>>>> 
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