LILO doesn't like my MBR - Slackware

This is a discussion on LILO doesn't like my MBR - Slackware ; I'm trying to install Slackware 12.0 on a newly built PC (Intel DG965RY motherboard, Core 2 Duo, SATA disk, IDE CD). If I install LILO in the MBR, the PC BIOS says "No bootable device. Insert boot disk and press ...

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Thread: LILO doesn't like my MBR

  1. LILO doesn't like my MBR

    I'm trying to install Slackware 12.0 on a newly built PC (Intel DG965RY
    motherboard, Core 2 Duo, SATA disk, IDE CD). If I install LILO in the MBR,
    the PC BIOS says "No bootable device. Insert boot disk and press a key."

    To get this thing to boot Slackware 12.0, I have to put a different loader
    in the MBR (such as: lilo -M /dev/sda), make my Slackware root partition
    (/dev/sda1) active, and put LILO in that partition's boot record.

    I've done LILO in the MBR on different PCs going way, way back without any
    problems, so this is a first. Has anyone seen this or have any idea why?

  2. Re: LILO doesn't like my MBR

    On Thu, 09 Aug 2007 00:23:35 +0000, ljb wrote:

    > To get this thing to boot Slackware 12.0, I have to put a different
    > loader
    > in the MBR (such as: lilo -M /dev/sda), make my Slackware root partition
    > (/dev/sda1) active, and put LILO in that partition's boot record.


    > I've done LILO in the MBR on different PCs going way, way back without any
    > problems, so this is a first. Has anyone seen this or have any idea why?


    Is there another OS on that HD? What are the partitions?

    Maybe look at man rdev which suggests syslinux as an option found at...

    http://syslinux.zytor.com/index.php

    My bet is that it's something real simple that you've overlooked though.
    Don't do anything drastic just yet.

    --
    Linux Help: http://rsgibson.com/linux.htm
    Email - rsgibson@verizon.borg
    Replace borg with net


  3. Re: LILO doesn't like my MBR

    On 2007-08-09, ljb wrote:

    > I've done LILO in the MBR on different PCs going way, way back without any
    > problems, so this is a first. Has anyone seen this or have any idea why?


    You say a new OS, but don't say which. Is it one of the newer gen
    Windows like w2k or xp? As I understand it, these are non-dos based
    OSs and so I would expect the fdisk /mbr command to not really be the
    real deal. Have you tried running fdisk /mbr from and old w9x floppy boot
    disk or old dos floppy? I used a w98 boot floppy and it worked
    perfectly despite slack actually being mounted on a second scsi drive.

    nb

  4. Re: LILO doesn't like my MBR

    ljb wrote:
    > I'm trying to install Slackware 12.0 on a newly built PC (Intel DG965RY
    > motherboard, Core 2 Duo, SATA disk, IDE CD). If I install LILO in the MBR,
    > the PC BIOS says "No bootable device. Insert boot disk and press a key."
    >
    > To get this thing to boot Slackware 12.0, I have to put a different loader
    > in the MBR (such as: lilo -M /dev/sda), make my Slackware root partition
    > (/dev/sda1) active, and put LILO in that partition's boot record.
    >
    > I've done LILO in the MBR on different PCs going way, way back without any
    > problems, so this is a first. Has anyone seen this or have any idea why?


    Are you sure that you have indeed installed lilo on that disk? (less -f
    /dev/sda should give something with "LILO" in the firs character.
    Strange is that it works when you install another mbr on that disk so
    the bios recognise it. Could it be that the bios check for the standard
    mbr? Try a google search with lilo or bios> grub (since the problem is likely to appear with grub as well).

    Olive

  5. Re: LILO doesn't like my MBR




    notbob wrote:

    >Have you tried running fdisk /mbr from and old w9x floppy boot
    >disk or old dos floppy? I used a w98 boot floppy and it worked
    >perfectly despite slack actually being mounted on a second scsi
    >drive.


    It is also possible, using MS-DOS or Windows 9X DOS, to
    completely clear the mbr, partition table, and everything
    else that differentiates a hard disk with a messed up
    install of some OS from a blank, unformatted disk. This
    allows whatever OS you are installing to make a fresh start
    when stting up the boot record and partition table.

    ------------------------------------------------------------------

    MS-DOS DEBUG Script to Clear First Sector of Hard Drive

    USE ONLY IF YOU WEANT TO DESTROY ALL TRACES OF ALL OS INSTALLS
    IN ALL PARTITIONS, ALONG WITH PARTITION TABLE AND BOOT RECORD

    ------------------------------------------------------------------

    The following DEBUG script will clear the partition sector
    (cyl 0, head 0, sector 1) of the first hard drive, which will
    force FDISK to completely start over. This will remove all
    partitioning, no matter what the OS. I have tested it and
    used it to remove all traces of Linux, DOS, BSD, QNX, Disk
    Manager, EZ Drive, and Windows (NT, 2K, 2003, XP and Vista).
    It should also remove any boot sector viruses, providing that
    the virus is not active in memory, (boot from a non-infected
    diskette to make sure). Although this script clears only the
    first physical drive, it is a good idea to unplug any other
    drives to prevent accidental data loss.


    Type in the following at the DOS prompt:

    A:\>DEBUG
    - f 200 L200 0
    - a 100
    xxxx:0100 mov ax,301 ("xxxx" segmentffset values will vary)
    xxxx:0103 mov bx,200
    xxxx:0106 mov cx,1
    xxxx:0109 mov dx,0080
    xxxx:010C int 13
    xxxx:010E int 3
    xxxx:010F (Press ENTER an extra time here)
    - d 100 LF
    xxxx:0100 B8 01 03 BB 00 02 B9 01-00 BA 80 00 CD 13 CC
    (Check and make sure that hex values match above line before
    proceeding; if values do not match, type Q and start over)
    - g=100
    (ignore register display)
    - q (quits back to DOS)

    FDISK should now show "No partitions defined".

    ------------------------------------------------------------------

    Explanation of script:

    (all values are in HEX)

    - f 200 L200 0 FILL Length of 512 bytes at offset 200 with value 0
    - a 100 ASSEMBLE program at offset 100
    (Next 4 lines set up registers for INT13 - Function 03)
    mov ax,301 AH=03 INT13 function 03 - Write Disk Sectors
    AL=01 specifies how many sectors to write (1)
    mov bx,200 BH=02 BL=00 points to buffer area at offset 200
    mov cx,1 CH=00 specifies cylinder 0 for INT13 function 03
    CL=01 specifies sector 1 (first sector on drive)
    mov dx,0080 DH=00 specifies head 0 (first head on drive)
    DL=80 specifies physical fixed disk drive 1
    (81=2nd drive, 82=3rd drive, 83=4th drive)
    int 13 call INT13 (BIOS Fixed Disk Device Service Routine)
    int 3 return to DEBUG (after assembling program)
    - d 100 LF this line is optional - the resulting hex dump can be
    used as a check to verify that instructions have been
    entered correctly
    - g=100 GO - run program stored at offset 100
    - q QUIT DEBUG back to DOS prompt

    ------------------------------------------------------------------


    Note from Guy Macon : I have tested this
    method on a wide variety of drives, old and new -- everything
    from an original IBM 5MB drive to external USB disks to a virtual
    partition on a hardware RAID array. In my experience, if MS-DOS
    FDISK can find the drive, this method will reliably clear the MBR
    and partition table.

    I am looking for the original author of this so I can give proper credit.


    --
    Guy Macon




  6. Re: LILO doesn't like my MBR

    Guy Macon wrote:

    > Type in the following at the DOS prompt:
    >
    > A:\>DEBUG
    > - f 200 L200 0
    > - a 100
    > xxxx:0100 mov ax,301 ("xxxx" segmentffset values will vary)
    > xxxx:0103 mov bx,200
    > xxxx:0106 mov cx,1
    > xxxx:0109 mov dx,0080
    > xxxx:010C int 13
    > xxxx:010E int 3
    > xxxx:010F (Press ENTER an extra time here)
    > - d 100 LF
    > xxxx:0100 B8 01 03 BB 00 02 B9 01-00 BA 80 00 CD 13 CC
    > (Check and make sure that hex values match above line before
    > proceeding; if values do not match, type Q and start over)
    > - g=100
    > (ignore register display)
    > - q (quits back to DOS)
    >
    > FDISK should now show "No partitions defined".
    >


    Nice when you're bored, want to erase your HD, and you realy feel
    that typing:
    dd if=/dev/zero of=/dev/hda bs=512 count=1 ; sync
    as root on a (linux) command line would be way too easy.


    Regards,

    Kees.

    --
    Kees Theunissen.

  7. Re: LILO doesn't like my MBR




    Kees Theunissen wrote:
    >
    >Guy Macon wrote:
    >
    >> Type in the following at the DOS prompt:
    >>
    >> A:\>DEBUG
    >> - f 200 L200 0
    >> - a 100
    >> xxxx:0100 mov ax,301 ("xxxx" segmentffset values will vary)
    >> xxxx:0103 mov bx,200
    >> xxxx:0106 mov cx,1
    >> xxxx:0109 mov dx,0080
    >> xxxx:010C int 13
    >> xxxx:010E int 3
    >> xxxx:010F (Press ENTER an extra time here)
    >> - d 100 LF
    >> xxxx:0100 B8 01 03 BB 00 02 B9 01-00 BA 80 00 CD 13 CC
    >> (Check and make sure that hex values match above line before
    >> proceeding; if values do not match, type Q and start over)
    >> - g=100
    >> (ignore register display)
    >> - q (quits back to DOS)
    >>
    >> FDISK should now show "No partitions defined".

    >
    >Nice when you're bored, want to erase your HD, and you realy feel
    >that typing:
    >
    >dd if=/dev/zero of=/dev/hda bs=512 count=1 ; sync
    >as root on a (linux) command line would be way too easy.


    On a system that will boot a DOS floppy disk but not Linux,
    running dd isn't quite so easy. Which is why notbob asked him
    whether he had tried running fdisk /mbr from and old Win9X or
    DOS floppy. And why I told him about the DOS DEBUG method
    for those times whenDOS FDISK /MBR fails.

    If you can get the system to boot off of a Live CD or a
    floppy-based Linux distibution, using dd is indeed simpler.


    --
    Guy Macon



  8. Re: LILO doesn't like my MBR

    Guy Macon wrote:
    > Kees Theunissen wrote:
    >>Nice when you're bored, want to erase your HD, and you realy feel
    >>that typing:
    >>
    >>dd if=/dev/zero of=/dev/hda bs=512 count=1 ; sync
    >>as root on a (linux) command line would be way too easy.

    >
    >
    > On a system that will boot a DOS floppy disk but not Linux,
    > running dd isn't quite so easy. Which is why notbob asked him
    > whether he had tried running fdisk /mbr from and old Win9X or
    > DOS floppy. And why I told him about the DOS DEBUG method
    > for those times whenDOS FDISK /MBR fails.
    >
    > If you can get the system to boot off of a Live CD or a
    > floppy-based Linux distibution, using dd is indeed simpler.


    You don't realy need a floppy based distribution.
    Every set of Slackware boot/root installation floppies
    released in, say, the last ten years will do.

    But let's focus on the OP's problem.
    He wrote that he _can_ install a loader in the MBR
    using "lilo -M /dev/sda" and boot the active linux
    partition where he had put LILO in the partition's
    boot record.
    But booting with LILO installed in the MBR fails.

    I realy want to see his partition listing
    (output from "fdisk -l /dev/sda") and his
    failing /etc/lilo.conf.


    Regards,

    Kees.

    --
    Kees Theunissen.

  9. Re: LILO doesn't like my MBR

    Guy Macon says:
    >notbob wrote:


    >>Have you tried running fdisk /mbr from and old w9x floppy boot
    >>disk or old dos floppy? I used a w98 boot floppy and it worked
    >>perfectly despite slack actually being mounted on a second scsi
    >>drive.


    >It is also possible, using MS-DOS or Windows 9X DOS, to completely
    >clear the mbr, partition table, and everything else that
    >differentiates a hard disk with a messed up install of some OS from
    >a blank, unformatted disk. This allows whatever OS you are
    >installing to make a fresh start when stting up the boot record and
    >partition table.


    Way to go, fatboy!

    MSDOS! We knew you wouldn't let us down.

    cordially, as always,

    rm

  10. Re: LILO doesn't like my MBR

    Kees Theunissen wrote:
    > Guy Macon wrote:
    >> Kees Theunissen wrote:
    >>> Nice when you're bored, want to erase your HD, and you realy feel
    >>> that typing:
    >>>
    >>> dd if=/dev/zero of=/dev/hda bs=512 count=1 ; sync
    >>> as root on a (linux) command line would be way too easy.

    >>
    >>
    >> On a system that will boot a DOS floppy disk but not Linux,
    >> running dd isn't quite so easy. Which is why notbob asked him
    >> whether he had tried running fdisk /mbr from and old Win9X or DOS
    >> floppy. And why I told him about the DOS DEBUG method
    >> for those times whenDOS FDISK /MBR fails.
    >> If you can get the system to boot off of a Live CD or a floppy-based
    >> Linux distibution, using dd is indeed simpler.

    >
    > You don't realy need a floppy based distribution.
    > Every set of Slackware boot/root installation floppies
    > released in, say, the last ten years will do.



    And so does Tomsrtbt floppy. Am using it as it is much simpler than the
    Slack way.

    Stanislaw
    Slack user from Ulladulla.

  11. Re: LILO doesn't like my MBR

    Stanislaw Flatto wrote:

    > And so does Tomsrtbt floppy. Am using it as it is much simpler than the
    > Slack way.


    That would seem to show that we both have very old fashioned hardware, I had
    a young visitor the other day who on seeing my computer with a 'funny
    little drive slot' asked what it was for, as apparently no one uses floppy
    drives anymore, or even builds them into the front of computers.
    --
    Two Ravens
    "...hit the squirrel..."

  12. Re: LILO doesn't like my MBR

    notbob@nothome.com wrote:
    > On 2007-08-09, ljb wrote:
    >
    >> I've done LILO in the MBR on different PCs going way, way back without any
    >> problems, so this is a first. Has anyone seen this or have any idea why?

    >
    > You say a new OS, but don't say which. Is it one of the newer gen
    > Windows like w2k or xp? As I understand it, these are non-dos based
    > OSs and so I would expect the fdisk /mbr command to not really be the
    > real deal. Have you tried running fdisk /mbr from and old w9x floppy boot
    > disk or old dos floppy? I used a w98 boot floppy and it worked
    > perfectly despite slack actually being mounted on a second scsi drive.


    No, sorry for being unclear, this was a brand new never used totally
    Windows-free hard drive. I created the partition table with fdisk or
    cfdisk from Slackware setup, and before that the disk was totally blank.

  13. Re: LILO doesn't like my MBR

    olive001@tele2allin.be wrote:
    > ljb wrote:
    >>...

    >
    > Are you sure that you have indeed installed lilo on that disk? (less -f
    > /dev/sda should give something with "LILO" in the firs character.
    > Strange is that it works when you install another mbr on that disk so
    > the bios recognise it. Could it be that the bios check for the standard
    > mbr? Try a google search with lilo or > bios> grub (since the problem is likely to appear with grub as well).


    Yes, I did dump the MBR (something like: hexdump -n 512 -C /dev/sda)
    and saw the LILO in there.

    It does seem that the BIOS is being fussy about what's in the MBR. Yet
    it will boot the "DOS-like" MBR provided with LILO (lilo -M), which is
    not the DOS MBR although it works like one.

    As far as I can tell, the BIOS claims only Intel ownership. That is, I
    can't find any other name. It looks roughly like a lot of other BIOSes
    (cyan top line, blue menu line, gray background, right side-bar) but
    presumably Intel has totally re-branded it.

  14. Re: LILO doesn't like my MBR

    Two Ravens wrote:
    > Stanislaw Flatto wrote:
    >
    >> And so does Tomsrtbt floppy. Am using it as it is much simpler than the
    >> Slack way.

    >
    > That would seem to show that we both have very old fashioned hardware, I had
    > a young visitor the other day who on seeing my computer with a 'funny
    > little drive slot' asked what it was for, as apparently no one uses floppy
    > drives anymore, or even builds them into the front of computers.

    Oh, the good old age!

    Have fun

    Stanislaw.

  15. Re: LILO doesn't like my MBR

    Kees Theunissen wrote:
    > Guy Macon wrote:
    >> Kees Theunissen wrote:
    >>> Nice when you're bored, want to erase your HD, and you realy feel
    >>> that typing:
    >>>
    >>> dd if=/dev/zero of=/dev/hda bs=512 count=1 ; sync
    >>> as root on a (linux) command line would be way too easy.

    >>
    >>
    >> On a system that will boot a DOS floppy disk but not Linux,
    >> running dd isn't quite so easy. Which is why notbob asked him
    >> whether he had tried running fdisk /mbr from and old Win9X or DOS
    >> floppy. And why I told him about the DOS DEBUG method
    >> for those times whenDOS FDISK /MBR fails.
    >> If you can get the system to boot off of a Live CD or a floppy-based
    >> Linux distibution, using dd is indeed simpler.

    >
    > You don't realy need a floppy based distribution.
    > Every set of Slackware boot/root installation floppies
    > released in, say, the last ten years will do.


    Replying to myself: this is not true. Modern hardware
    (like sata disks) will no be supported by those old kernels.
    An old DOS floppy with debug will be able to access modern
    hardware as long as it only uses BIOS calls to access the
    disk (and the BIOS still supports the old function calls,
    and as long as you only want to access the first few megs
    of the disk).

    But the OP succeeded to install linux on his new computer.
    He really has all tools handy that might be needed to
    manipulate the MBR.

    I'm wondering what went wrong with the OP's installation
    of LILO in the MBR. It might be something simple/stupid as
    the BIOS looking for an 'active flag' in one of the partition
    table entries before handing control over to the MBR boot
    code. Lilo will not use, nor need, the 'active flag'. But
    this flag won't hurt if it is present. And if the BIOS looks
    for it....

    When LILO was installed in the MBR for the first time the
    original master boot sector was probably saved as
    "/boot/boot.0800".
    It would be helpful if we could see a listing of the contents
    of that file. Use: hexdump -C /boot/boot.0800



  16. Re: LILO doesn't like my MBR




    Two Ravens wrote:
    >
    >Stanislaw Flatto wrote:
    >
    >> And so does Tomsrtbt floppy. Am using it as it is much simpler than the
    >> Slack way.

    >
    >That would seem to show that we both have very old fashioned hardware, I had
    >a young visitor the other day who on seeing my computer with a 'funny
    >little drive slot' asked what it was for, as apparently no one uses floppy
    >drives anymore, or even builds them into the front of computers.


    I recently bough a new Dell Optiplex 745 (I needed a newer cpu
    with virtualization extensions so as to run 64-bit guest operating
    systems on a 32-bit host OS with VMWare Workstation), and I checked
    the floppy option. It turned out to have a USB floppy drive, not
    an old-fashioned FDD floppy drive. I rarely boot with a floppy or
    use a floppy for data transfer now -- USB thumb drives really are
    better in most ways -- but a PC with no floppy controller at all?
    Ah well, might as well get used to the New World Order...

    --
    Guy Macon




  17. Re: LILO doesn't like my MBR

    In alt.os.linux.slackware Guy Macon says:
    >Two Ravens wrote:
    >>Stanislaw Flatto wrote:


    >>That would seem to show that we both have very old fashioned
    >>hardware, I had a young visitor the other day who on seeing my
    >>computer with a 'funny little drive slot' asked what it was for,
    >>as apparently no one uses floppy drives anymore, or even builds
    >>them into the front of computers.


    We bought my computer, a Dell garbagecan, and of course it has a
    traditional floppy drive. We haven't looked at Dell's lately, but
    they all had floppies, the last time we looked.

    Apple dumped their floppy, at least on some models, 10 or 15 years
    ago, while floppies were still essential in the PC world.

    >I recently bough a new Dell Optiplex 745 (I needed a newer cpu
    >with virtualization extensions so as to run 64-bit guest operating
    >systems on a 32-bit host OS with VMWare Workstation),


    Who are you trying to impress, Fatboy? Nobody cares about why you
    bought your new computer and the information is not in any way
    relevant to the conversation. So what is your point?

    >and I checked the floppy option. It turned out to have a USB
    >floppy drive, not an old-fashioned FDD floppy drive. I rarely boot
    >with a floppy or use a floppy for data transfer now -- USB thumb
    >drives really are better in most ways -- but a PC with no floppy
    >controller at all? Ah well, might as well get used to the New
    >World Order...


    And yet, in a prior post, you give us an MSDOS debug script, and you
    claim to be interested in Freedos. You are truly pathetic. Please
    stop posting. Everybody feels the way we do, but they are too
    polite to say it.

    cordially, as always,

    rm

  18. Re: LILO doesn't like my MBR

    theuniss@rijnh.nl wrote:
    >...
    > I'm wondering what went wrong with the OP's installation
    > of LILO in the MBR. It might be something simple/stupid as
    > the BIOS looking for an 'active flag' in one of the partition
    > table entries before handing control over to the MBR boot
    > code. Lilo will not use, nor need, the 'active flag'. But
    > this flag won't hurt if it is present. And if the BIOS looks
    > for it....


    Very clever. Brilliant, in fact. I confirmed this: the Intel DG965 BIOS
    is checking to make sure at least one partition on the disk is marked
    "active" (or "bootable"). It doesn't even have to be the partition you are
    booting from! So with LILO in MBR, if I mark any partition "bootable", then
    LILO boots and does what it was configured to do. With no partition marked
    "bootable", the BIOS refuses to run LILO from the MBR - even thought LILO
    does not care about bootable partitions.

  19. LILO doesn't like my MBR *SOLVED*




    In alt.os.linux.slackware, ljb wrote:
    >
    >theuniss@rijnh.nl wrote:
    >
    >> I'm wondering what went wrong with the OP's installation
    >> of LILO in the MBR. It might be something simple/stupid as
    >> the BIOS looking for an 'active flag' in one of the partition
    >> table entries before handing control over to the MBR boot
    >> code. Lilo will not use, nor need, the 'active flag'. But
    >> this flag won't hurt if it is present. And if the BIOS looks
    >> for it....

    >
    >Very clever. Brilliant, in fact. I confirmed this: the Intel
    >DG965 BIOS is checking to make sure at least one partition
    >on the disk is marked "active" (or "bootable"). It doesn't
    >even have to be the partition you are booting from! So with
    >LILO in MBR, if I mark any partition "bootable", then LILO
    >boots and does what it was configured to do. With no
    >partition marked "bootable", the BIOS refuses to run LILO
    >from the MBR - even thought LILO does not care about bootable
    >partitions.


    Here is what I think is happening:

    In the Original IBM PC MBR, having no active partition table
    entry was the way you told the PC that you want to run ROM
    BASIC via INT 18 rather than boot to any of the partitions.
    Non-IBM systems have no BASIC ROM, so they usually throw an
    error message, but some BIOSs just hang or reboot on INT 18.
    Others say to insert a floppy or to hit ESC|F1|F10|Etc. to
    run BIOS setup. The ideal BIOS behavior is to return after
    doing nothing.

    The standard LILO MBR and the standard GRUB MBR Only use INT 10
    and INT 13, not INT 18, and thus should work no matter how the
    BIOS responds to INT 18.

    Here is what I believe is a complete list of what happens
    with various Microsoft and IBM MBRs created by FDISK.

    IBM Personal Computer DOS 1.00 and 1.00 only used INT 10, INT 13,
    and INT 16, with ROM BASIC invoked by having no floppy. 1.x didn't
    know what a hard drive was and thus only had a floppy MBR.

    MS-DOS 2.00 through MS-Windows 95 had this in the MBR:

    061D BEBE07 MOV SI,07BE ; Start of partition table
    0620 B304 MOV BL,04 ; 4 partition Table Entries.
    0622 803C80 CMP BYTE PTR [SI],80 ; Is it 80h (active)?
    0625 740E JE 0635 ; Yes, done.
    0627 803C00 CMP BYTE PTR [SI],00 ; No, Is it a 00?
    062A 751C JNE 0648 ; No, invalid partition table.
    062C 83C610 ADD SI,+10 ; Next PT entry.
    062F FECB DEC BL ; Decrement Entry Counter.
    0631 75EF JNZ 0622 ; Not done, Test another entry
    0633 CD18 INT 18 ; Done none active, call ROM BASIC
    0625 [...] ; start of next test

    Windows 95B, 98, 98SE and ME had this in the MBR:

    061B BEBE07 MOV SI,07BE ; Start of partition table
    061E B104 MOV CL,04 ; 4 partition Table Entries.
    0620 382C CMP [SI],CH ; Is high bit set?
    0622 7C09 JL 062D ; Yes, done.
    0624 7515 JNZ 063B ; No, invalid partition table.
    0626 83C610 ADD SI,+10 ; Next PT entry.
    0629 E2F5 LOOP 0620 ; Test another entry
    062B CD18 INT 18 ; Done none active, call ROM BASIC
    062D [...] ; start of next test

    Win NT, 2000, 2003 and XP have this in the MBR:

    061B BDBE07 MOV BP,07BE ; Start of partition table
    061E B104 MOV CL,04 ; 4 partition Table Entries.
    0620 386E00 CMP [BP+00],CH ; Is hfirst byte zero?
    0623 7C09 JL 062E ; Yes, done.
    0625 7513 JNZ 063A ; No, invalid partition table
    0627 83C510 ADD BP,+10 ; Next PT entry.
    062A E2F4 LOOP 0620 ; Test another entry
    062C CD18 INT 18 ; Done none active, call ROM BASIC
    062E [...] ; start of next test

    As for Vista, Microsoft Vista has some serious partitioning incompatibilities.
    See [ http://www.multibooters.co.uk/partitions.html ]. I don't have any
    information on the Vista MBR and what it does with no active partition, and I
    am not about to let it mangle my partition table in order to find out.

    --
    Guy Macon




  20. Re: LILO doesn't like my MBR *SOLVED*

    Guy Macon wrote:

    >
    >
    >
    > In alt.os.linux.slackware, ljb wrote:
    >>
    >>theuniss@rijnh.nl wrote:
    >>

    - - - - - - - < SNIP > - - - - - - -

    > Here is what I think is happening:
    >
    > In the Original IBM PC MBR, having no active partition table
    > entry was the way you told the PC that you want to run ROM
    > BASIC via INT 18 rather than boot to any of the partitions.
    > Non-IBM systems have no BASIC ROM, so they usually throw an
    > error message, but some BIOSs just hang or reboot on INT 18.
    > Others say to insert a floppy or to hit ESC|F1|F10|Etc. to
    > run BIOS setup. The ideal BIOS behavior is to return after
    > doing nothing.
    >

    - - - - - - - < SNIP > - - - - - - - -
    > --
    > Guy Macon
    >



    That was a nice job, especially with the boot assembly examples.

    --
    humjohn AT aerosurf DOT net

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