Bios Rom checksum error

Discussion in 'Computer Information' started by William, May 14, 2008.

  1. William

    Paul Guest

    3 minutes should be enough time for a flash update, and your EEPROM is
    256KB, so the thing isn't that big. Still, I'd be careful with pressing
    the reset button too quickly.

    Did you investigate the command line options for the flash program at
    all ? For example, if you can still boot to DOS, can you use the flash
    program to make an archival copy of the current contents of the
    flash chip ? Then, examine the file with a hex editor, and see what
    is in there. These are some examples of what you might see in the existing
    256KB archival file.

    Address 0 - Main BIOS
    Code modules delimited with "-lh5-"
    On the PCChips M811LU V3.1 board, the module names I can
    see are "a.BIN", "awardext.rom", "ACPITBL.BIN", "AwardBmp.bmp",
    "awardeyt.rom", "_EN_CODE.BIN", "via_pxe.lom" (for network boot).
    Each code module is compressed with LHA. The main BIOS body
    is checksum protected. As far as I know, the boot block won't
    jump into the main code, unless the checksum is good. The
    first steps to using the code would be, decompression, followed
    by shadow copy into system RAM.

    Address 0x27240 - A blank area. I don't see DMI and ESCD default values in
    the rest of the file. On an archived file from a working
    computer, this area of the EEPROM could have been overwritten
    as a normal part of the BIOS POST process. DMI and ESCD are
    updated according to the hardware present. This area may also
    contain text strings, like a serial number put there by the
    system builder (using a DMI utility). Ideally, it would
    make the most sense, if these areas were aligned to a
    block boundary, as the flash could be segmented, and to update
    DMI or ESCD, you'd want to erase some number of blocks, to
    make room for the info.

    Address 0x3E000 - Boot block starts here, and runs to 0x3FFFF. This is an
    8K piece of code, which is what is currently being used
    to boot from the floppy.

    For a hex editor, you can use a program like this one. Their free edition.

    The M811LU V3.1 motherboard has a manual, even if it is a bit skimpy.
    Unzip to find a PDF manual. Skip to page 31.

    On page 31, you can see "BIOS Flash Protect" and the default value
    is [Disabled]. If you clear the CMOS, then the default value should be
    put back there. That is the only thing I see in the manual, that could
    prevent the flash update from happening. The M811LU doesn't appear
    to have a jumper to prevent flash updating.

    When flashing, always make sure the flash file is the right size. If the
    board documentation says it is a 256KB EEPROM, then a 256KB (262144 byte)
    file should be used to flash the board. Similarly, when you make your
    archive copy of the current rom, it should also weigh in at 262144 bytes.
    If I look at the options for the award flash program, pn means "No
    flash programming" and sy means "backup original BIOS". What I'm not sure
    about, is whether the syntax has to have two file names (even though we're
    not flashing here), or just the filename that will be used for the
    archival copy.

    awdflash.exe backup.bin /pn/sy

    And checking here, that does appear to be a usable syntax.

    When you look at the BIOS flash options, there are these:

    Sb = Skip boot block
    Wb = Write boot block

    Writing the boot block is dangerous, in the sense that you
    may not be able to boot into DOS any more, if this goes wrong.
    That is how motherboards get bricked, by the boot block being
    corrupted (erased but the programming fails to complete).
    Skipping the boot block, means the area from 0x3E000 to 0x3FFFF
    should not get updated.

    Some BIOS flashers beep when the flash update is complete.
    But I don't know enough about all of them, to say what to
    expect in this case. There are later Award Flasher programs
    with slightly more screen information displayed, and that can
    make it easier to see how the thing is going. This web page
    shows an example of a more elaborate GUI.

    Paul, May 18, 2008
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  2. William

    Baron Guest

    I have a sneaky feeling that the wording implies that the BIOS is set to
    be flashable, but the opposite is true.

    That would also explain the very rapid transition to a blank screen when
    the flash utility was run.

    Otherwise a comprehensive explanation from Paul.
    Baron, May 18, 2008
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  3. William

    William Guest

    Before I go any further let me run something by both of you. I installed
    the Syntax mother board myself back in 2005 and was able to use my old CPU
    which is 1GHz. I purchased the board from Tiger Direct for $39.95 and got a
    29.95 rebate so I really don't have much money tied up. The mother board has
    worked fine for the five years. Since my computer trouble shooting and
    proceduers knoeledge are very limited do you think I would be better off
    just upgrading my computer or buy a new one? If both of you are still
    willing to deal with my lack of knowledge I am still willing to learn. It
    just might take a while. I do like to fix things.
    William, May 18, 2008
  4. William

    Baron Guest

    If you are willing to play around a little, I don't mind ! We both
    might learn something !

    Can you get into the BIOS settings screen ? Usually "Del" or "F2" on
    boot up.

    If so change the "BIOS write setting" to "Enabled" and re-try the flash
    utility. Don't make any changes ! Just read the instructions and if
    there is one any "readme" file on the floppy.

    Make sure that you understand them !

    Next step is to make a copy of the existing BIOS. The flash utility will
    give you this option. Give it a name that you can recognise. You may
    need another blank floppy for this. The one that you are using should
    be write protected or a copy of the original. The ideal is to use a
    copy, then it doesn't matter if it gets damaged.

    Since you can boot a floppy its a simple matter to make one.
    Baron, May 18, 2008
  5. William

    William Guest

    Thanks Baron. Here is where I am now. I can't get to BIOS. When I push and
    hold down the delete key or the f2 key on boot up the floppy is read but
    does not go to (A) prompt. The flash utility I have only has one option and
    that is to enter file name for flash. Where can I get a flash utility with
    more options? Something else, computer will not turn off or reboot unless I
    use switch on back or reset. If I to turn it off by the switch on back I
    have to turn it on and off several times before it will boot at all and
    sometimes I have to use reset. Would it be better for me to remove all
    perifials and all cards except video card? I made the msdos startup disk I
    use to boot on my other machine from windows. Was that OK?
    William, May 18, 2008
  6. William

    Baron Guest

    Ok ! Based on what you have just said I would seriously consider biting
    the bullet and junk the main board. Its unlikely that you would get a
    board that supports your CPU and ram ! So I would look at a main
    board, CPU, Ram combination to replace it.

    The Nvidia 6100 series main boards with built in video, sound, network
    card, USB, SATA/IDE and floppy are a good choice. These support an AM2
    dual core CPU and 4GB+ ram. Gigabyte is a favoured manufacturer of
    mine since it uses solid dielectric capacitors on the main board. Its
    also 100% Linux compatible.
    Baron, May 18, 2008
  7. William

    William Guest

    Thanks for all your help. I also appreciate the sugestion on the mother
    board. Just for my satisfaction take a look at this mother board and give me
    your openion.
    My CPU is AMD Athlon Duron Socket A 462-pin 1GHz. My Memory consists of 2
    unbuffered 2.5v 184 pin slots and supports DDR SDRAM PC2100/PC1600.
    Thanks again.
    William, May 18, 2008
  8. William

    w_tom Guest

    Learn from your experience. If my posted two minute procedure had
    identified the error, then a flashing program may have only added more
    BIOS damage.

    If BIOS was truly defective, then computer never once powered on
    without reporting that checksum error. If it powered on only once
    with no checksum error, then flashing the BIOS may have only created
    another defect. As I read it. sometimes computer powered on without
    reporting a checksum error. That means checksum was not the problem -
    only a symptom.

    Is the motherboard defective? Maybe not. But until measurements in
    that two minute procedure are made, then defect could be anywhere (and
    maybe not motherboard).

    Never flash a BIOS if power is unstable or uncertain. However some
    BIOS may be recovered if unstable power is first identified and
    w_tom, May 19, 2008
  9. William

    Paul Guest

    In terms of the economics, if you were to go to and
    order a new flash chip, to stick in the socket where the old one
    is located, that would cost $30. A new motherboard, at $39, is
    not much more expensive. So from that perspective, not a big deal.
    But when I look at the specs, I notice the Tigerdirect FSB spec
    is 266,333,400, and there is no FSB200 for the older processors.
    But I did find the CPU support page for M848A V5.0, and the Duron
    is down at the bottom of the page. So the new board looks OK and
    the Duron should work in it. (You might want to download the
    manual and read all about the motherboard, before buying it.)

    For the flash program, the extension on the end of the file name,
    might have been important. Some programs want to see .bin on the
    end of the file name, and others look for .rom . But since
    it doesn't seem to be booting that far any more, it'll be
    a bit more difficult to recover. (If it won't touch the floppy
    drive at all, that is when you know that even the boot block
    is gone.) If you can still get the flash program to work, then
    you could continue to play with it.

    If the new M848A doesn't boot properly, you can inspect the power

    There is no reason for a flash chip to fail, based on a power supply
    problem. If so, then many other things could be damaged in the
    computer at the same time. Like hard drives can be pretty sensitive
    to a power supply problem. But I don't see a reason for *just* the
    flash chip, to be the only thing affected in the computer. But flash
    chips can fail on their own, when they get old enough. On motherboards
    around 10 years old, this is called "bit rot", and has affected the
    odd 440BX board. But it shouldn't prevent the flashing program, from
    trying to reflash the chip.

    As for the suggestion of removing excess hardware, yes, that would
    also be an interesting experiment.

    Paul, May 19, 2008
  10. William

    William Guest

    Learn from your experience. If my posted two minute procedure had
    identified the error, then a flashing program may have only added more
    BIOS damage.

    If BIOS was truly defective, then computer never once powered on
    without reporting that checksum error. If it powered on only once
    with no checksum error, then flashing the BIOS may have only created
    another defect. As I read it. sometimes computer powered on without
    reporting a checksum error. That means checksum was not the problem -
    only a symptom.

    Is the motherboard defective? Maybe not. But until measurements in
    that two minute procedure are made, then defect could be anywhere (and
    maybe not motherboard).

    Never flash a BIOS if power is unstable or uncertain. However some
    BIOS may be recovered if unstable power is first identified and

    I appreciate any input to help me solve this problem. I don't mean any
    disrespect to you but your post seemed to me more of a reprimand than a
    help. You are right in that concerning power supply outputs the numbers are
    important. I do not belive any damage has been done because everything is
    the same. I am 67 years old and have bad eye site and I am not a technician
    so I am reluctant to do certain things. I am not going to be in any hurry to
    purchase a new mother board.
    Have a good day.
    William, May 19, 2008
  11. William

    William Guest

    Thanks Paul for all your help. I will not be in any hurry to make any
    purchases. I will do some more testing and I will read the specs on the new
    mother board before I make a dicision. I did down load another flash utility
    and that did not work either. Have a good evening.
    William, May 19, 2008
  12. William

    Baron Guest

    Hi William,
    That board looks like it should be Ok. Its virtually identical to the
    one you already have.

    When it comes to swapping over the CPU make sure that you use a good
    quality heatsink compound. I use "Artic Silver 3" when I do
    CPU/heatsink cleanups.
    Baron, May 19, 2008
  13. William

    Baron Guest

    I would hope that William checks out the PSU before he goes ahead with a
    main board replacement. Particularly since you can get a bare bones
    machine for $100 and I've seen notebook machines for $200
    I agree !
    It would, but only in terms of minimising PSU loading !
    Baron, May 19, 2008
  14. William

    William Guest

    Thanks Baron. I just think I have'nt lost much if it don't work. Also I
    don't think I can remove the BIOS chip anyway. Where do I "Artic Silver 3"?
    There is some kind of white paste on the bottom of the CPU. Where can I get
    William, May 20, 2008
  15. William

    w_tom Guest

    Except I was not discussing damage. Discussed are failures that do
    not cause hardware damage - implying the motherboard can be fixed once
    the real problem is identified and eliminated. When voltages are
    marginal, chips fail (nobody said anything about damage). However if
    voltage is marginal and BIOS is flashed, then strange data
    (temporarily destructive) can be saved - more checksum errors. That
    is only two types of failures. One that occurs only this time.
    Another that causes bad data. And a third (which I never suggested)
    that is hardware damage - replace the motherboard.

    If a power supply is not verified, the many symptoms in the OP's
    posts are also associated with marginal voltages - also known as a
    defect elsewhere (ie power supply system).

    So we replace that motherboard. then have a same (marginal) power
    supply defect. Then what? Another example of replacing parts without
    first learning the problem; also called shotgunning.

    Again, failures here are also consistent with a marginal power
    system. Nothing says a power supply system is bad because numbers are
    not provided. Those failures say zero about hardware damage or a
    damaged motherboard. Those checksum errors are also consistent with a
    power system defect. If that problem exists, then flashing can even
    contaminate the BIOS or simply fail. To eliminate that failure reason
    takes less than 2 minutes. Discussed were failures - not hardware
    damage. Curiously, William has repeatedly posted symptons consistent
    with a defective power 'system'.
    w_tom, May 20, 2008
  16. William

    Baron Guest

    William Inscribed thus:
    Good Morning William,
    That white paste is the heatsink compound that I referred to ! The
    white paste stuff is just not good enough for modern CPU's. Hence the
    recommendation for artic silver.

    You would need to ask locally to you. The last tube, 3 grams, I bought
    cost me 75p UK, a little over a Dollar. It also lasts a long time, 20
    or 30 applications in a tube. The advantage is that it doesn't dry out
    with the heat like the white paste does.

    Re BIOS chip. I think on that board it is a surface mount device that
    you will not be able to remove without specialised tools. On better
    quality main boards it is usually in a socket.

    As far as w-toms advice is concerned, it is only valid under some
    conditions ! Also w_tom forgets that we are not all engineers
    experienced in measurement diagnostics. His assumptions and belief are
    based on "All computer failures are PSU based" ! Now I am sure that
    few will disagree that PSU problems are a major cause of computer
    failures, but not all computer failures.

    Indeed in my years as an engineer a high proportion of failures are due
    to damage from failing to take proper anti static precautions when
    handling these very sensitive components. I see many machines that
    have failed or give unpredictable behaviour simply because sufficient
    care has not been taken during component handling and machine
    Baron, May 20, 2008
  17. William

    w_tom Guest

    Static created failures and (more common) manufacturing defects are
    major reasons for semiconductor failure. But there is no reason to
    believe semiconductor failure exists Measuring voltages is so
    *complex* that multimeters are sold to Kmart shoppers. If measuring
    voltages are so difficult, then a person must never own a cell phone
    or Ipod - which are more and too complex.

    Power is not the most common source of damage. But no reason to
    believe damage exists. Fixing with unstable power means anything can
    appear defective. 30 seconds to measure voltage reports so much.
    Bios will not flash? Again, symptoms of a power problem. Checksum
    error occurs intermittently? Another symptom of defective power.

    Well it might be a bad chip, or might be too much heat, or might
    be ... that is called wild speculation. Is defect in the power
    system (which is more than a power supply)? 30 seconds to have a
    definitive answer - no speculation – no shotgunning.

    Intermittent checksum error does not come from heat or from
    defective BIOS code. That intermittent is symptom more common to other
    problems. A most common reason - bad power system - can be identified
    or exonerated in only 30 seconds. Nothing identifies a suspect faster
    or more definitively. One who cannot switch a meter to VDC, touch
    probes, and then read a number has no business trying to fix a
    computer OR using a cell phone. Measuring voltages is that simple.
    Nothing posted says the motherboard is defective. Nothing posted says
    CPU heat has significance.

    30 seconds to identify or exonerate a common reason for all those
    symptoms. So simple that only fear could impede that act. Not
    relevant to checksum errors is CPU heat. Fixing a checksum error with
    thermal compound is only wild speculation. Known facts do not suggest
    CPU heat.
    w_tom, May 20, 2008
  18. William

    William Guest

    Hey Baron or Paul
    I installed new mother board and after a few tries I had to set the
    bios on the fail safe setting. Message came up "Windows could not start
    because the following file is missing or corrupt"
    "You can attempt to repair the file using the orignal setup CD-Rom". Is this
    because of the new mother board?What would you suggest I do?
    William, May 28, 2008
  19. William

    Baron Guest

    Unless you have done a clean install of Wins you will get these
    problems. Wins doesn't like it when you swap mainboards on it !
    I always do a clean install on a new mainboard.
    Baron, May 28, 2008
  20. William

    William Guest

    Thanks Baron. Just two more questions. Should I run the setup disk that
    came with the mother board? If I do a clean install do I have to register
    windows xp again and how about the password and will I loose all my other
    programs? Thanks.
    William, May 28, 2008
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