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Old 07 June 2013, 11:45   #10

phx's Avatar
Join Date: Nov 2009
Location: Herford / Germany
Posts: 1,601
Originally Posted by Toni Wilen View Post
I'd create big copper list that has as many wait/move pairs as you have vertical pixels (2048?). WAIT only waits for end of horizontal line, MOVE changes background color.
Ahhh! Now I understand! Maybe mc6809e also said that, but I didn't get it.

The WAIT instructions will only wait for end of line, but ignore the VPOS. Something like $00df,$00fe? After writing to COLOR the next line has started and I can wait for end of line again. Very good idea!

When you need to move split point, replace color register write with write to COPJMPx (and restore old COPJMPx with COLOR0 write) which handles the split and color change (if also needed) and finally jumps back to big copper list.
Ok. The only question here is whether the number of available memory cycles until DDFSTART are sufficient to load the pointers for all five bitplanes, write the COPJMP and COLOR.
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