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Xeda112358:
You can edit the pages on wikiti btw. As for the mirrored port writing being ignored, that's actually really handy to know. I suspect that two different people contributed those facts, or maybe it was he came person who forgot?
the_mad_joob:
--- Quote from: Xeda112358 on August 03, 2020, 04:41:35 pm ---As for the mirrored port writing being ignored, that's actually really handy to know.
--- End quote ---
I found back my old 83+ from 1999, so i was finally able to test that.
So, i can confirm that writes to mirrored ports are definitely NOT ignored, updated my previous post.
At least, writing to port $20 had the exact same effect as actually writing to port $00.
Cheers.
Xeda112358:
Oh, thanks for confirming that. I know the code to set 15MHz mode does take some advantage of that, because it essentially writes a 0 to port 20h (mirror of the link port) on those calcs which is generally safe, but writes a non-zero value on the other calcs.
the_mad_joob:
--- Quote from: Xeda112358 on December 08, 2020, 08:13:42 pm ---Oh, thanks for confirming that. I know the code to set 15MHz mode does take some advantage of that, because it essentially writes a 0 to port 20h (mirror of the link port) on those calcs which is generally safe, but writes a non-zero value on the other calcs.
--- End quote ---
I actually just re-tested that method aswell.
While it's safe on the 83+BE if there's no link activity, i wouldn't recommend using it on other models, see my note on port $20 on my synthesis post.
NonstickAtom785:
--- Quote from: the_mad_joob on December 08, 2020, 08:21:22 pm ---
--- Quote from: Xeda112358 on December 08, 2020, 08:13:42 pm ---Oh, thanks for confirming that. I know the code to set 15MHz mode does take some advantage of that, because it essentially writes a 0 to port 20h (mirror of the link port) on those calcs which is generally safe, but writes a non-zero value on the other calcs.
--- End quote ---
I actually just re-tested that method aswell.
While it's safe on the 83+BE if there's no link activity, i wouldn't recommend using it on other models, see my note on port $20 on my synthesis post.
--- End quote ---
Well I made some of those fixes from above. You should get yourself an account :D .
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