ECS/AGA and DDFSTOP >= 228 (0xe4) results in full horizontal overscan bitplane DMA. Like someone had set DDFSTRT=0x18 and DDFSTOP>=0xd4.
Does not happen in OCS.
Also some "illegal" DDFSTOP values can cause complete display corruption, syncs get messed up etc... (don't remember the exact values now)
Non-aligned DDFSTRT values cause bitplane delays (BPLCON1) work incorrectly. Basically hidden offset which depends on DDFSTRT is added to shift value. (I have called it "delayoffset". New Zealand Story, James Pond II AGA, Pinball Illusions, Loons Docs disks, Overkill AGA etc..)
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