'Shackled (Data East)'
Author:Lord Crass (guest: search)
Date: Wed, May 04th, 2011 @ 22:35 ( . )

I figured Shackled would be the HI MIKE protection, but it isn't. The protection has a custom loader for 4 sectors on track 18 and 5 sectors on track 27, then reverts to regular load routines.

The custom loader checks that the data block sync marks on track 27 are longer than usual (at least 75 bits or so) or it retries forever.

This protection should defeat fast copiers or software nibblers because they write standard length syncs instead of measuring the source's sync and reproducing it accurately. The parallel/8k copiers do a better job with this and should reproduce it correctly (as does nibread).

For a software-only solution, a custom copier could be written that writes sync marks of 80 bits in length. The data block gap length could be reduced so that this fits without needing to reduce drive speed. Of course, it's easier to just crack the protection...


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