This problem is driving me crazy.

I've used an old Gigabyte mobo (GA-5AX Rev 5.2) with an AMD
K6-2 500Mhz cpu to build a small box on which I've installed
Puppy. The bios F3 needs upgrading to F4.

I have the new bios zip-file, and a W98 Startup disk, but
don't seem able to find a flash program compatible with
Gigabyte.

Go to Award or Gigabyte's web site you say. I'm tired of
trying to get anywhere - Award has merged and appears
to have set up an outfit named 'eSupport' which will do
the job for me for $30 (I can buy a new simple PCChips board
for that!!). Gigabyte seem to say they can provide everything
needed if I go to their download site - it's been impossible
to get the (which seems sinister to me!)

Anyone know a flash program which will work? And could
someone detail the steps to be taken. I've gone through
literally thousands of pages on Google, but apart from one
interesting suggestion that it is best to put both the flash
program and new bios file on a CD instead of a floppy, I've
found nothing to help. Flashing seems a simple enough
procedure if undertaken with care (and backing up).

a neurotic rabelais.

http://www.uniflash.org/

This may give back your peace of mind.

It is very important that you understand that your bios is the most basic part of your computer. It is the primary "operating system". You can only use a bios specifically released by the manufacturer for THAT motherboard. Get the wrong bios or do the flash incorrectly and your computer will never work again. You have been warned.
Most manufacturer's have a section on their website that details exactly how to flash the bios and have the bios files available. Briefly the process requires getting the package (sounds like you have) unzip the file and study the readme that comes with it VERY CAREFULLY (preferably print it). Every one that I have come across requires booting from a basic boot disk then executing the excutable and then follow the on screen requests. Do not at any stage cut the power to the box while flashing.

Whilst I understand TigerOC's comments, they really are based on "modern" BIOS and/or motherboard. Hopefully the makers of which (both) are still in existence.
Just this very afternoon (Aussie time remember) I went looking for a BIOS update so I could maybe get my oldest heap (Pentium 90) to boot from CD.

I feel the pain of the OP - it's a real bitch trying to get anything for kit this old.

My solution - it ain't worth the grief.
This was to be a test box only, so I'll go get a case and build a new one from scratch.

Did a quick Google search and found the bios flash file at the Gigabyte site here. This is the flash file. Download the file and then copy to a working dos formated floppy. Set your system to boot from the floppy and boot the system with a boot disk. Once your have the A:> prompt insert the disk with flash file and do A:>dir then do A:>bios_5ax_f4.exe and follow the on screen instructions.

Thanks, all responses are helpful.

However, uniflash's offering may not cover specically my mobo,
so I'll leave that for the moment.

TigerOC's last response should allow me to go forward. It
seems that my frustration may have arisen from a
misunderstanding and having read too much. I've been
looking for three things:-
1. A bootdisk (it seems a W98 startup
will do - which I have).
2. A specific flash program.
3. The new bios file - this also I have.

I'll follow TigerOS's advice later in the day and let all
know how I got on. Like syg00, this is not critical - I can
get a cheap uptodate mobo - but, as I've never flashed
a bios before (each time I might have done so I bought a
new mobo and a faster cpu), I thought it a good time to
learn.

By the way, there's no README when the f4 file is unzipped.

I've now succeeded, but not without a few headaches on the way.

Eventually everything went very smoothly as much to say "why all
the worries".

The file to which TigerOC referred and the one I had already
located did not work and returned an error message "This program
must be run under W32".

A file '5AX.F4', which looked strange did the job. I've just run
'bootdet' which confirms the upgrading.

I'm grateful for the invaluable help. If I have to flash again I now
feel confident I can manage.