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Old 02 August 2009, 19:29   #17
Toni Wilen
WinUAE developer
 
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 44
Posts: 22,943
Thanks, I can confirm this. There are really weird things happening...

Blitter gets totally confused when channel mode=1 gets switched to D while blit is already active. I checked the cycle diagrams with logic analyzer:

Clear blit, -D-D-D-D... write 0x?D?? to DFF040 and cycle diagram changes to officially non-existing BACBACBAC. (correct channel combination should have been ABD)

I don't know how to explain this without knowing blitter internals but this does explain why memory is not corrupted (=demo does not crash), blitter only reads, it never writes anything...

EDIT: I didn't notice this because I did 2 mistakes, I didn't check it with LA and I had blitter nasty set = "BAC" does not have any free cycles -> CPU stopped before write to BLTSIZE, writing to BLTSIZE when blitter is idle -> blitter resets cycle diagram, blitter writes again..
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