[Coco] is there any existing 6847 output to RGB ? (for coco2)
didier derny
didier at aida.org
Sat Feb 21 09:58:18 EST 2015
In fact, Z18/Z19 are also on the NTSC mc10 so they are not involved in the 525 -> 625 conversion
We checked a Alice motherboard, the Z20 (Z18 on the pcb) seems to be a custom chip
>From MTE (Matra Tandy Electronic) the company building the Alice
So apparently this chips is doing all the conversion...
--
Didier
-----Message d'origine-----
De : Coco [mailto:coco-bounces at maltedmedia.com] De la part de Zippster
Envoyé : samedi 21 février 2015 14:51
À : CoCoList for Color Computer Enthusiasts
Objet : Re: [Coco] is there any existing 6847 output to RGB ? (for coco2)
Ah, now feeding the clock to the 6847 from a flip-flop makes sense.
They are actually pausing it while inserting the extra lines.
- Ed
> On Feb 21, 2015, at 12:54 AM, didier derny <didier at aida.org> wrote:
>
> 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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