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Old 29 December 2014, 18:59   #3
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Join Date: Aug 2004
Posts: 2,828
Thanks for the explanation.

Over in the Undocumented Amiga hardware stuff thread you wrote:
Last line of field works normally if A1000 Agnus. If later revision: last line inhibits both sprite and bitplane DMA. (This explains above demo's different OCS vs A1000 Agnus behavior)
That got me thinking, with A1000 Agnus maybe you can set overscan prefs to maximum height and not have the bottom line (or two for interlaced modes) of the WB screen blank/missing.

(These tests with Kickstart 3.1, PAL vertical overscan set to maximum.)
With OCS A1000 Agnus & OCS Denise: bottom line of WB screen is blank. There is a second blank line below that. [Same as with OCS Fat Agnus + ECS Denise.]

With OCS A1000 Agnus & ECS Denise: bottom line of WB screen is visible. Below that is a garbage line then an all-blank line. If you drag the WB screen down, it vanishes when you get within ~40 lines of the lowest position, reappearing as you drag back up. (I guess apart from the bottom line being visible, the other issues are due to Kickstart 3.1 assuming full ECS.)

Contrary to what I expected, in order for the bottom line of the WB screen to not be blank with A1000 Agnus, you have to configure ECS Denise, not OCS. Same as real hardware?
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