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Hank77 Hank77 is offline
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Default Flashing BIOS using only OS X with USB flash key - 03-18-2009, 04:55 AM

I've been lurking for a few weeks now... decided to return to the community, albeit a small contribution.

I updated to A04 using a small (32MB) USB flash key, and it worked fine.

Here's what I did:
1) Download the A04 BIOS from Dell's support site.
2) Download a DOS boot image (
3) Partition and erase USB key in Disk Utility as FAT (this might be optional).
4) In Disk Utility, unmount the newly formatted FAT volume.
5) Right click on the USB flash drive device, and click on "Information". Note the disk number (e.g. disk3).
6) Open Terminal and type the following:
sudo dd if=/<path to dos image>/Dos6.22.img of=/dev/<disk from above>
In my case, the command read:
sudo dd if=~/Desktop/Dos6.22.img of=/dev/disk3
7) Once dd has completed, mount the USB flash key again.
8) Remove all files except for: autoexec.bat, config.sys, io.sys, msdos.sys (I also left the following files alone: himem.sys,, just because I had managed to free up enough room). This clears up enough room (~1.2MB) to move the A04 BIOS files onto the 1.44MB disk image.
9) Copy over the A04 flash files. I just copied the folder named "910A04" over directly.
10) Eject the drive, plug into your mini, and it should boot! (USB legacy mode has to be enabled in the BIOS).
11) Follow instructions on Dell's support site to complete the BIOS update.

I hope this helps a few folks!

Thanks to the community for providing such comprehensive and quick responses and guides.

Now back to tackling a failing OS X install
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Timmy G Timmy G is offline
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Join Date: Mar 2009
Default Re: Flashing BIOS using only OS X with USB flash key - 03-23-2009, 01:44 AM

Hi Hank,

Thanks very much for the write up, it was 90% accurate to what I wanted to do but I just wanted to share a slightly easier way. I had issues that even when I imaged the standard DOS 6.22 image linked in this tutorial, it would say "No operating system found" before I even started deleting files.

I found following tutorial which did work @

You will find one of the files that thread links is missing, I found it at ...

This tutorial makes it a much easier and you don't need to delete any files, just copy the contents of the A04 ZIP and it all fits.


Timmy G

Current: Macbook 2.4Ghz aluminium .. with OS X
Previous: Dell Mini 9 with OS X
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tomz17 tomz17 is offline
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Default Re: Flashing BIOS using only OS X with USB flash key - 03-29-2009, 05:58 PM

Worked perfectly!

The only things I would add
#1) you need a small disk (so that it's fat 16 and not fat 32... it won't boot off a fat32 usb drive)
#2) I recommend leaving as well (sys and tree are not necessary)
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