Yes - that's right. The standard palette at FE21 is used to map logical colours to the 16 physical colours. The extended palette at FE23 is then used to map each of the 16 physical colours to a 12-bit RGB value.Rich Talbot-Watkins wrote:Ah yeah I get it, so it goes through two palette lookups - once through the standard palette to get an actual physical colour index, and then looks that up in your extended palette (is that right?).
In which case I see less need for a second switchable palette. Changing 4 6 colours per scanline (24us in the horizontal border, 12 STAs = 24us) is enough for nearly anyone's needs I would think, apart from certain exceptional problems like Dominic's HAM mode experimentation. As Beeb programmers we're used to working around limitations, and I suspect with careful image processing and exploiting midline palette changes, there might be ways to get even more colour changes in, in much the same way as your rainbow demo Rob
How would the indexing work? Some sort of auto-incrementing?Rich Talbot-Watkins wrote:Edit: it'd be a late change to make, but it would possibly be more versatile to split up the two writes in this way, so that the first set the most significant two bits of the RGB (doubled to the least significant bits), and an optional second write could fine-tune it by setting the least significant bits. Just a thought...
My plan is to work on the 12MHz modes tonight and then see how much space is left. I clawed some back when I put in the re-initialisation mechanism so there may be room for some additional stuff.