[Coco] Using a NTSC Coco in the UK - my findings

[Phill Harvey-Smith]

Quoting Torsten Dittel <Torsten at Dittel.info>:

>> A few years ago I was so lucky to snatch an Australian Coco 3 from eBay that
>> readily could be connected in Europe to both 240V power and PAL televisions
>> (though I still have the CM-8 from back then).
>
> Yeah, I prefer the Aussie version too. The PAL Composite Video signal
> ist not the (poor) NTSC signal generated by the GIME itself (this GIME
> pin is not connected in PAL machines) but it's mixed on an additional
> daughterboard directly from the RGB signal (software works even if only
> made for the RGB palette).

If this is the case would it not be possible to build a replica of  
that circuit and drive it off the RGB port ?

I have actually found the composite signal to not be that bad, for  
most of the time, however the black on green mode that Niros9 L2 boot  
into is pretty hard to read on my composite TV semms as if ajacent  
pixels are squashed into each other.

>                           The Aussie CoCo3 has a modified BASIC ROM
> which inits the GIME to 50Hz operation. Since most PAL monitors and TVs
> are able to display PAL with 60Hz (although this is outside the PAL
> specs) even software poking the GIME back to 60Hz works fine.

Yeah even my 25 year old black and white portable can cope with PAL-60 :)

I keep wondering about replacing the NTSC coco3 rom with a PAL image,  
but I'm also hesitating due to the problems I had getting the CPU out,  
i don't really want to damage the board anymore :(

Cheers,

Phill.


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