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MEGA65 / mega65-user-guide

MEGA65 User Guide
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Remove Auto-Tune section #587

Open ki-bo opened 5 months ago

ki-bo commented 5 months ago

Describe where we can find the problematic topic Appendix T, section "Track Auto-Tune Function" is deprecated and probably should be removed. The auto-tune function seems to be non-functional anymore. It looks like it was only implemented to work around another bug with the floppy controller, which is now solved and there is no need for the auto-tuning anymore.

Describe the solution you'd like Remove that section from the manual. The correct procedure to step the head to the correct track is already described in section "Reading Sectors from a Disk" directly before.

Additional context We should also remove the auto-tune flag from the fdc controller register $D696 description (bit 7). But this needs to be done in the core.

ki-bo commented 5 months ago

This is what I found in the core vhdl:

  -- (Actually the auto-tuner is now effectively defunct, as the bug that caused
  -- us to implement it has now been fixed).

I quickly tested it and for me, the track was not automatically seeked, and the requested sector was not found. Maybe it was an error on my side, though, but it seems the auto-tune is a feature either non-functional or at least not recommended.

ki-bo commented 5 months ago

Just tested again...

The documentation is just wrong. It states:

The 45IO27 also includes a track “auto-tune” function, which is enabled by clearing bit 7 of $D696.

In fact, it is enabled by setting bit 7 of $D696. It is in fact enabled by default and works. It makes strange noises when seeking the track, though. My own routine seeking the correct track seems to work more smoothly. We need to find a decision on whether this feature should stay or not.