AH = 05h
        AL = interleave value (XT only)
        ES:BX = 512-byte format buffer
                the first 2*(sectors/track) bytes contain F,N for each sector
                   F = 00 for good sector, 80h for bad sector
                   N = sector number
        CH = cylinder number (bits 8,9 in high bits of CL)
        CL = sector number
        DH = head
        DL = drive
Return: AH = status code (see AH=1 above)
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