MR> The head/cylinder numbers are relative to the beginning of the 
 MR> logical drive.  Sort of.  

I *suspect*, from experience with the Graham Utilities DISKEDIT, that you'll
find that your hypothesis does not work for multiple primary partitions (such
as is the case if Boot Manager is installed at the start of the disc, for
example).

 ¯ JdeBP ®

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