dos_cylindersectors
ptn_alignment = dos_cylindersectors;
#define SEC_TO_CYL(sec) (((sec) + dos_cylindersectors/2) / dos_cylindersectors)
dos_cylinders, dos_heads, dos_sectors, dos_cylindersectors,
cylinder = sector / dos_cylindersectors;
sector -= cylinder * dos_cylindersectors;
cyl = sector / dos_cylindersectors;
sect = sector - cyl * dos_cylindersectors;