[Coco] 64 column "low res" text sceen on coco3

[Robert Gault]

William Astle wrote:


> FF9C does (as has been documented elsewhere) sets up for higher semigraphics
> modes except that text rendering doesn't function correctly. It seems to
> function by reducing the character row height depending on the value put in
> FF9C. Text characters seem to be aligned with the bottom of the cell instead of
> the top so the top of the characters gets clipped as the lines per character row
> are reduced. In any mode that is not 12 lines per character row, the graphics
> blocks are rendered differently. The values for FF9C work as follows. Unless
> otherwise noted, the bottom two elements of each graphic block are shown for all
> lines of the character row. These have all been confirmed experimentally.
>
> 0: 11 lines per row
> 1: 10 lines per row
> 2: 9 lines per row
> 3: 8 lines per row
> 4: 7 lines per row
> 5: 6 lines per row
> 6: 5 lines per row
> 7: 4 lines per row
> 8: 3 lines per row
> 9 : 2 lines per row
> 10: 1 line per row
> 11: 4 lines per row (1)
> 12: 3 lines per row (2)
> 13: 2 lines per row
> 14: 1 line per row (4)
> 15: 12 lines per row (3)
>
><snip>

It took me awhile to discover that I've explored some of these options before. I 
think there was a discussion thread at coco3.com when Roger's site was active.

Anyway I had modified my program S24 (which is my Semigraphics-24 editor) to 
work on a Coco3 but without text on the graphics screen. All that was required 
was to set $FF9C =10   %1010 $0A.
So now the program sets $FF9C which has no effect on a Coco1 or Coco2 but 
permits most of the program functions to work with a Coco3.

Robert