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How to Recover from a corrupted BIOS flash
Published  06/21/2011 | Troubleshooting Computer | Rating:
How to Recover from a corrupted BIOS flash

Some of the main reasons for flash BIOS corruption are incompatible add-on cards, aborted flash updates due to power fluctuations (laptop users note: don’t flash while on battery, ensure you are plugged into a live wall outlet), or improper BIOS images.

If your flash attempt fails, don’t panic! Such failures are often reliably recoverable, as most newer BIOS codes today include a Boot Block Protection option. A BIOS of this type has two distinct parts. The first Boot Block part contains information needed to initialise only critical system devices such as the floppy drive, processor, memory and ISA video devices. This part is write-protected and cannot be overwritten by flashing. The second part is the flashable part, known as the System Block, and contains all the information needed to initialise other system devices such as video, storage, COM ports, input devices, other peripherals, and performing the POST.

To recover from a corrupted flash, you need to be able to boot into the floppy where you have the flash program and the BIOS file you want to flash. An ISA video card is preferable, but if you do not have one, you can still do it. If you have the ISA card then you will be able to see what you are doing. Reboot the system to the DOS prompt and repeat the steps outlined above for flashing, or the steps specified by your motherboard manufacturer. If you don’t have an ISA video card, create an autoexec.bat file, which will run when you boot into the DOS system. Use Notepad to a create a single line entry which will contain the flash program name followed by the update file name along with any switches that are specified. For example, the following line should be in the autoexec.bat file to flash an Award BIOS:

a: awd802.exe backup.bin /py /Sb /sn /cc /cp /cd /R.

This instructs the DOS system to run autoexec.bat when the system boots up and run the awd802.exe flash program using the backup.bin BIOS update file. The switches are various options specific to the flash program, with the last switch instructing the program to reboot once flashing is completed.

Copy the autoexec.bat file to the floppy with your flash program and the BIOS update file you want to use. The floppy should only contain the basic DOS system files, and should not have any other files (such as config.sys) that may auto-load on start up and interfere with the flashing.

The example above is for an Award BIOS update. While the parameters will most likely differ for your particular BIOS version, the general approach remains the same:
* Create a DOS system floppy
* Copy the flash program and the BIOS update file
* Create an autoexec.bat batch file with a single line entry instructing DOS to flash the BIOS when the system starts up Be sure to read up the manufacturer’s instructions on each switch parameter and how they should be used.


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