Paul Rogers wrote in a message to Roy J. Tellason:

 RJT> Did a search for the partition table sig bytes of 55AA,
 RJT> and I found a *bunch* of instances of it,  in most if not
 RJT> all cases at the end of a sector,  a fact I found
 RJT> interesting since I don't remember prior setups on that
 RJT> particular physical drive.

 PR> I remember 55AA from the CP/M days--that was the bit pattern
 PR> written to newly formatted diskettes.  55AA = 0101010110101010  It
 PR> makes a nice frequency for MFM detectors.

I thought that was E5,  which is what dos still uses to mark the first byte
of a filename in the case of a "deleted" file...

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