[Coco] Artifacting (again)

[jdaggett at gate.net]

On 3 Sep 2010 at 6:57, Mark McDougall wrote:


> On 2/09/2010 11:21 PM, Wesley Haynes wrote:

> 

> > Another possible discrepancy is that some coco2 SAM chips (mine included)

> > produced somewhat different artifact colors. My orange / blue SCREEN 1,1

> > mode always looked more pinkish red / greenish cyan if you know what I mean.

> > That is, the red was a little brighter than pure red, and the green was

> > bluer than pure green but much greener than true cyan (text mode CLS 6,

> > e.g.).

> 

> I think you mean 6847, rather than SAM. The SAM doesn't affect the video 

> output, just the video memory addressing.

> 


Mark

The SAM chip also expands the video modes. S8, S12 and S24 modes  are added via the 
SAM chip. The INV, and S/A pins of the 6847 are also mapped to the DD
/DD7 pins of the SAM chip. Supposedly this is to allow changes on the fly. 


james