2)  FDISK /MBR (Concluded)

    Paul, I work _only_ with the Microsoft versions, and have not had the
    same experience.  The /MBR parameter _only_ rewrites the MBR.  It does
    not affect the partition information.  I use it daily on various
    machines and have not lost one byte of data.

                              Matt Mc_carthy

    I guess you didn't know that "Master Boot Record" and "Partition Table"
    refer to the same thing.  What you're talking about is the master boot
    CODE, the executable code that accompanies the partition table and is
    located on the same physical sector (0).

    Here's what I find in the first few bytes of my physical sector 0
    (unassembled with DEBUG after copying the sector to a file):

    2BB7:0100 33C0            XOR     AX,AX
    2BB7:0102 FA              CLI
    2BB7:0103 BED0            MOV     SS,AX
    2BB7:0105 BC007C          MOV     SP,7C00
    2BB7:0108 BEC0            MOV     ES,AX
    2BB7:010A BED8            MOV     DS,AX
    2BB7:010C FB              STI
    2BB7:010D 8BF4            MOV     SI,SP
    2BB7:010F BF0006          MOV     DI,0600
    2BB7:0112 B90002          MOV     CX,0200
    2BB7:0115 FC              CLD
    2BB7:0116 F3              REPZ
    2BB7:0117 A4              MOVSB
    2BB7:0118 EA1D060000      JMP     0000:061D

    I also find the following text in the first half of the sector:

        Missing operating system.Error loading operating system.Invalid
        partition table.Author - Siegmar Schmidt

    I have only one partition on my C: drive, and its information is in
    the last of four possible positions in the partition table. The first
    significant byte (non-zero) is at offset 01EEh in physical sector 0.
    The rest, from offset 00EDh to 01EDh is nothing but 00h.

    So it would appear that everything from offset 0000h to 00ECh is the
    Master Boot CODE, and everything from 00EDh to the end of the sector
    (01FFh) is the Master Boot RECORD (aka partition table). More likely,
    the partition table probably begins at offset 0100h, and takes up the
    last 256 of the 512 bytes available in the sector.

    Beginning with the first significant byte of my partition table (at
    offset 01EEh), this is what mine shows:

       80 01 01 04 03 91 65 11 00 00 00 07 A3 00 00 55 AA
       ^^
    This first byte, I think, is the drive on which this partition
    is located, and the next byte might indicate that this is the
    first (primary) partition (in my case, the ONLY partition for
    this drive).

    Now, according to my manual, FDISK /MBR can either re-write only
    the Master Boot CODE when necessary; or it can re-write both the
    Master Boot Code AND the Master Boot RECORD, if it determines that
    the partition table has been corrupted.

    If it does re-write both, then you do have to use FDISK without
    the /MBR switch after using it with the switch, because the
    re-written partition table has no defined partitions until you do.
    But when you use the /MBR switch, it produces no screen output
    (at least not on the version I'm using), so you don't know whether
    it did both or just the code. So you should still check to see that
    you have a valid partition by using FDISK without the /MBR switch
    afterwards.

                              Paul Maserang

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