Posted By
Murphy
on 2023-07-25
16:51:26
|  Re: Carrion's 121 colors - new slideshow from Carrion
@seff I don't know who was the first, but Udo Gertz was way ahead of his time, that's for sure. Attila KosÃr, who I remember used the border in all the games he made, but those are from '88-89.
The counter reset is a bit special here. The $ff1d/1c counter would normally be set to 152 (200-48) before the 200th line and the screen would continue for another 6 character rows. Of course, at the end of the screen, the counter must be reset to the correct value.
What makes it necessary to write $ff1d every 2nd line is that I do FLI mode with this register. This takes up the whole CPU where there are graphics.
And the rest of the messing around is just to make the screen structure continuous, and thus make the image swapping routine much simpler. Normally, the color memory counter would go from 1000 to 1023 in the 26th character row, and then flip over mid-row and continue with the 0 to 15 area.
|
