scsi hdd can't be seen when installed a ati rage 128 on pci slot

Discussion in 'Asus' started by efos, Dec 11, 2006.

  1. efos

    efos Guest

    how ca i solve this problem ? i'm installing a new viveo card on my
    ibm p4 1.7 with scsi hdd on it the scsi controller is installed on pci
    slot 5 and and did install my video card on slot 1 or 2 but when i
    reboot my pc i get message system halted operating system cannot load
    efos, Dec 11, 2006
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  2. efos

    efos Guest

    efos, Dec 11, 2006
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  3. efos

    Gerry_uk Guest


    You need to give the EXACT error message and describe the screen where
    you see it. "System Halted" and "Cannot load operating system" are two
    different things.

    "System Halted" is usually a BIOS message (not related to SCSI)

    "Cannot load operating system" (or similar) is after it's found the disk
    controller but can't make sense of the boot sector.

    You also need to give the exact make model of your SCSI controller,
    Video card, mainbaord, o/s etc. It's possible the video card hardware
    interrupt has conflicted with the SCSI controller, but this is extremely
    rare on PCI with modern kit.

    Check also your BIOS defaults in case you have forced any IRQs.
    Gerry_uk, Dec 11, 2006
  4. efos

    Paul Guest

    There is a critical resource in low memory (below 640KB), used during
    boot. On a desktop motherboard, the memory area in question might be
    limited to 128KB.

    Things that share this memory are:

    1) video card BIOS (there is a BIOS chip on the video card)
    2) storage card BIOS (there is a BIOS chip on the SCSi controller)
    3) network bootable networking card (PXE)

    When a computer has a number of devices like that, the computer can
    run out of the type of low memory needed. It is a first come
    first serve system, so the add-in BIOS modules get their memory
    allocation, in the order of enumeration. What it can mean,
    is a storage card whose BIOS used to load (like a SCSI card),
    suddenly can no longer load. And for the SCSI card, if the
    SCSI BIOS does not load, the computer cannot boot from the
    SCSI card. This quotation from Tyan Tech Support is where I
    first learned of this:

    Q: Why doesn't the BIOS (Option ROM) for my PCI device show
    during boot up?

    A: The cause of the problem is that in order to be PC Compatible,
    the Option Rom space is limited to 128K. This is true for any
    motherboard with PC compatible BIOS'.

    In the common configurations, a newer AGP card (such as any
    GeForce4) will require 64K of Option Rom space, so you have only
    64K of Option Rom space left to work with for other devices.
    Many SCSI, NIC (w/ PXE), IDE Raid and etc., can easily use
    another 40 to 64K of Option Rom space for their needs.

    By design the Option Rom should shrink down to a smaller run time
    code after the initialization code has run. For example, some Adaptec
    cards will require 32K to initialize. Then they shrink down to
    12K at run time; whereas some GeForce4 cards require 64K to initialize
    and never release to a smaller amount. Please check with the device
    manufacturer for the latest firmware upgrade or ask if they have a
    smaller Option Rom available. Again this is a limitation of the
    PC compatible specification and not a failure of the motherboard
    BIOS itself.

    The normal solution to this, is to either disable any unneeded option
    ROMs. (For example, if the motherboard network interface supports
    PXE, disable the network boot ROM in the BIOS. If you have three
    SCSI cards, disable the BIOS on the two you are not booting from.)
    Or, change the slots that the cards are plugged into. For example,
    if the SCSI card is plugged into PCI slot 1 (the PCI slot closest
    to the processor), then the SCSI card gets enumerated before any
    other PCI cards. It could be, that it will result in the other
    PCI cards, not being able to use their Option ROM, but it may
    allow the computer to boot.

    Paul, Dec 11, 2006
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