[Coco] Converting from coco 1 / 2 artifact graphics to color coco 3

[Robert Gault]

David Roper wrote:

> Hi all,
> 
> What's normally involved in converting a game that runs using artifact 
> graphics for coco 1 / 2 into a game that runs using 16-color coco 3 
> graphics modes? I've seen it done with a few games, and I'm curious as 
> to what the process would involve.
> 
> There's quite a few interesting games out there that run in fake-colour 
> mode, and such colour modes aren't available here in Australia (due to 
> using the PAL system).. all we get is muddy grey and some freaky pinks 
> and greens occasionally :)
> 
> Anyone actually done such a conversion?

In theory, it is simple but in most cases the results are not 
satisfactory. All artifact graphics screens are PMODE4, that is 
typically 256x192x2. Change the mode to PMODE3 (128x192x4) and adjust 
the colors used to white, black, red, blue and you will get a screen 
similar to but not the same as the original. The main problem which 
can't be corrected is that any text drawn with widths of a single pixel 
becomes illegible.

A recent thread asked about The Interbank Incident on RGB systems. I 
have created a patched version of bank which gives good color on RGB 
systems but most of the text can't be read. As there are many messages 
in this game, the game becomes almost unplayable on a PMODE3 screen.

  So, with a simple theory, is it a practical exercise to convert a 
game? No it is not! You need to be a very good assembly programmer and 
able to both find the correct part of the pertinent program, disassemble 
it, and patch it.
  Don't think t will be possible to find a Coco3 HSCREEN that will make 
the process easier. Using a 16 color screen would ruin any details in 
the graphic as four of the original pixel will now be a single pixel. A 
4 color HSCREEN would be identical to a PMODE3 screen.