but since copper DMA Chip ram access is conditioned by DMA priorities and competes with other stuff how's one supposed to know where the changes end up occurig?
DMA cycles are reserved for their specific purpose. At least they are on OCS. I don't remember exactly, but I think there are five or six cycles for bitplanes, one for copper, one for sound and one for trackdisk. And in the beginning of each display row there are eight cyles for sprites.
Maybe on AGA some cycles are shared, so for example I could imagine that you loose some copper cycles if you use more than six bitplanes.
I know that on OCS the sprite cycles are shared with the display DMA, so you loose one sprite after another if you expand the bitfield to the left.
Perhaps the reservation is the reason why you are disappointed about the copper resolution. IIRC on OCS one copper instruction was four pixels wide (or eight high-res pixels).
Bye,
Thomas
