Added by foft over 6 years ago. Updated over 6 years ago.
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Description
So white on black is currently good, while black on white should be better. Seems related to the rise/fall times...
Phaeron got a scope on it:
http://atariage.com/forums/topic/244946-using-pulse-density-modulation-for-8-bit-pcm/page-7#entry4036484
Looks to be high pass filter propagation delay related.
Tried a 1 cycle and a half cycle delay on the input to the xor. Neither are seeming quite right, but 1 cycle delay is closest...
Been checking on the scope. The one cycle delay looks correct.
Some jitter issues due to when I activate pokey. I was doing so on the memory access completion, but this really varies too much when accessing SDRAM and block RAM. So I've changed it to activate on the final cycle, as with antic.
Seems to run fine, Acid now passes again as far as I can tell.
Reopening, inconsistent timing in calibrate
The issue was that the write to stimer was now exactly on the enable cycle. I modified the latch delay line to support this. Fundamentally though, this isn’t meant to happen, so perhaps an issue with the pbi implementation is causing the writes to be on an unexpected cycle??
Found the issue when doing the pokeymax work - I'd lost some changes by accident.