How to Flash a BIOS

By ·Categories: Industrial IoT, Tech Explained·Published On: October 12th, 2012·3.3 min read·

We recently published a blog post discussing the clearing of a computer’s CMOS. Clearing the CMOS can be an extremely valuable tool, but sometimes simply re-setting that configuration is insufficient. Certain types of BIOS corruption will require a full re-write of the data on the CMOS chip. This operation is generally referred to as a BIOS flash, and can also be used to update a mainboard’s BIOS to the latest version.

Similar to the way software companies release updates to their programs to add new functions and fix bugs, mainboard manufacturers will also occasionally release firmware (BIOS) updates to fix minor issues and enable new features on mainboards. Support for additional CPU’s and different brands/capacities of RAM are good examples of functions that can be added with a newer BIOS version. As with software updates, firmware (BIOS) updates can also introduce new bugs and/or lack capabilities that older versions had – because of this, it is important to check the release notes or version history of your mainboard’s BIOS before applying an update.

The Jetway NF99 mainboard is a good example of a board which has had multiple revisions to its BIOS, which have both improved reliability and added functionality. This tutorial will use the NF99 as an example on BIOS flashing – different mainboards may require very slight alterations to the procedure.

Flashing the BIOS on the NF99

The first step in flashing the BIOS on an NF99 is to look at the BIOS section of that mainboard’s page on the manufacturer’s website. Visit the board’s product page here – click BIOS to enter the appropriate section of that page.

Jetway NF99

It is highly advisable to use the DOS version of the BIOS flashing utility whenever possible – the Windows versions should be avoided, as they are notorious for causing problems.

Download the DOS version of the BIOS – Extract that .zip file to a folder on your computer. Notice that the BIOS flashing utility – AFUD431.EXE – was provided inside of that .zip file, negating the need to download the utility separately from the NF99 web page. AFUD431 is the program which can be run from DOS in order to apply the BIOS update to the mainboard.

The other files you will now have are BF99AA09.ROM and BF99AA09.BAT – the .ROM file is the actual BIOS for the NF99 mainboard, and the .BAT file is a DOS batch file which tells the utility (AFUD431) which .ROM file to apply to the mainboard.

Clear You Bios

Before going any further, you will need to create a DOS boot disk for your computer to boot from. This can be done, for free, on any computer with access to the internet as long as you have some sort of storage media available. A hard drive, USB flash stick, CD-R/RW, or even a 3.5” floppy disk will work. For instructions on creating a DOS boot disk, see Booting DOS from a USB Drive.

Once you have a DOS boot disk, copy the files which you extracted from to it. You now have a bootable DOS disk with a copy of the A09 BIOS for the NF99 mainboard and the BIOS flashing utility on it.

At this point, you will have to shut down your computer and boot it up from the DOS disc that you just created. Once inside of DOS, simply type in BF99AA09 and press the Enter key. The AFUD431 utility will run, and will automatically start flashing the BF99AA09 ROM file to your mainboard.

Flash Utility Running

When the BIOS update is finished, you will be left at the DOS prompt again with the message “Program ended normally”. The BIOS has now been updated, and you can remove the DOS boot disk, reboot the system, and resume using it.

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About the Author: Travis Bigelow

I joined Logic Supply a little over two years ago, and have been falling deeper and deeper in love with the embedded PC world ever since. During my off-time I am an avid mountain biker, and despite being a self-proclaimed "geek", I'm often ridiculed for never having seen the Star Wars movies.