[Coco] A new Composite Video board for the MC-10

[Didier Derny]

In fact, the Alice 4k has an interface with a handful  of transistors 
(around 12)
to transform the output of the 6847 into  a 625 lignes rgb signal (no 
composite at all)
if you check the schematics you will find:
- a custom chip to stop the 6847 clock to produce blank lines (for the 
missing lines)
- a A + B + CHB + Y conversion to RGB

roughly the Alice 4K is a MCS  without rf modulator but in place this 
6847 to scart (rgb) interface)
the other Alice uses a different chip from Thomson EFCIS

http://alice.system-cfg.com/alice.php

http://alice.system-cfg.com/files/A4K_schema.png


I'm trying to reproduce this interface without the 525->625 lines conversion
(my converter accept 525 lines)


my mc10 is a qwerty NTSC mc10





On 03/08/2015 17:53, Torsten Dittel wrote:
> Zippster <zippster278 at ...> writes:
>
>   
>> The boards are designed for NTSC MC-10s as RF modulator replacements.
>> They wouldn’t fit anything else AFAIK.
>>> On Aug 2, 2015, at 11:34 PM, Torsten Dittel <OS-9 <at> TRS-80.CC>
> wrote:
>>> Do you have an NTSC board? I fear it
>>> doesn't work on European PAL board (not
>>> even fit). If you have a French RGB board,
>>> it doesn't make sense at all (no RF
>>> modulator in there...
> That's what I meant (of course Ed's boards are high quality designs)...
> :-)
>
> There were basically 3 MC-10 board types sold: The NTSC version in the US,
> a PAL version for Europe and Australia (I know of different RF modulators
> and PAL versions for UK, Australia and Central Europe (DE, NL, BE)) and as
> a third variant the French RGB Version (PAL/SECAM "Peritel" RGB out,
> AZERTY keyboard layout) which is similar or even equal to the board in the
> Alice 4K.
>
> I still assume your board doesn't fit in any of the PAL versions.
>
> Regards,
> Torsten
>