pm_ResSectors
pmp->pm_ResSectors = getushort(b50->bpbResSectors);
pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
pmp->pm_ResSectors = getushort(b50->bpbResSectors);
__func__, pmp->pm_BytesPerSec, pmp->pm_ResSectors,
pmp->pm_fatblk = pmp->pm_ResSectors;