[Coco] Re: [Color Computer] CoCo 2 questions.

[Phill Harvey-Smith]

Mike Pepe wrote:
> 
> Phill Harvey-Smith wrote:
> 
>>Glen VanDenBiggelaar wrote:
>>
>>
>>>Hi, Phill,
>>>What Model number is it?
>>
>>
>>26-3136A It is a UK PAL version tho.
> 
> I have a scan of that schematic. It's pretty hefty at 9MB...

Wouldn't mind a copy of that, do you have somewhere where you could put
it temporarly for until I can download ?

>>So looks like upgrade is indeed 2x41464, doesn't work at the moment, so 
>>if you (or anyon else) have a circuit for this model would be most 
>>greatfull.
> 
> The official upgrade is 8x64kx1, but you can do 2x64kx4 if you want.

Right, I did wonder what those white connectors where for, daughtercard
with 8x41256 presumably :)

>>Fault is vertical lines of @ down the screen, I suspect a data path 
>>fault, ie one of the LS chips that sits between Ram and VDG and RAM and 
>>CPU.
> 
> If you pulled the 785 and popped it in the dragon, it's not that then.

Nope was not that.

> I'd guess dead 6809. If the video chip is dead that's going to be hard 
> to find, it should be a 6847T1 in there. (not compatible with the normal 
> 6847)

6809 is alive and kicking, turned out to be the 4416 RAM chips, replaced 
them with a couple of 4464s scaved off an old MDA card, set the 64k link
and presto it fired up.

What's the difference between the normal 6847 and the T1 ?

> the A model, by the way, is a 16k extended basic. The B version is 64k.

Right, that makes sense....though this A now has 64K :)

Phill.



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