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WOZ: All even disk i/o read accesses will read the data latch #672

tomcw opened this issue Jul 30, 2019 · 2 comments


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commented Jul 30, 2019

From #662, @peterferrie said:

At $8D2E, LDA $C08E,X is returning the wrong nibble (#$AD instead of #$FF, and that #$FF should be about to be dropped).

OK, I'm only updating the latch for $C0EC. So this #$AD is from the previous $C0EC latch read, ie. when it read D5AAAD. But, yes, strictly speaking all latch reads (ie. $C0En even addresses) should update the latch. I'll fix that.

@tomcw tomcw added the bug label Jul 30, 2019
tomcw added a commit that referenced this issue Jul 30, 2019
. Even disk i/o read accesses will update the data latch
. All disk i/o write accesses will update the data latch

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commented Jul 31, 2019

Not strictly related to this WOZ reading problem, but I remember that some groups of the french underground cracking scene in the 80s loved to use "exotic" addresses for their reading routine (like $C0E0 instead of $C0EC).
When I was doing disk preservation, I had to patch a lot of these 'fresh' .DSK to work on AppleWin.
Could you also fix this issue for DSK ?
I can send you some DSK for tests if you want!


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commented Sep 7, 2019

I converted some of your .dsk's to .woz, and was able to test this - so I'll close this one.
And the specific fix for .dsk/nib is being tracked in another issue.

@tomcw tomcw closed this Sep 7, 2019
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