Video
Card Bios Misflash by
Louie
May 27, 2000
Most video cards,
like motherboards, come with programmable BIOS. And much like motherboards,
some popular video cards like the TNT2 Ultra and Savage4 have BIOS
updates. Bios flashing isn't that hard actually, the only problem
is how to recover when your flash fails. How does one recover from
a bios misflash or how do I make bios flashing safer? Only one answer
comes to mind except for the option of not flashing at all which does
defeat the purpose of ever wanting to flash.
MakeTSR
What is
this MakeTSR program? Well to make a long discussion short, it basically
turns your ROM files into executable files. This allows the bios to
be called from a batch file (for our purposes, that would be the autoexec.bat).
But how would making the Bios executable help? By letting the autoexecute
batchfile to call the bios, you don't modify the bios on the video
card itself. What happens is that the bios that's in the exe file
is the one used. This means that in essence, you could try out any
bios file you want with relative ease and with no danger of damaging
the vid card at all!
Usage: (these
are dos commands)
maketsr <romfile>
After the file
is generated, you have to make an autoexec file that calls the exe
file. Use a command similar to this:
LH a:\<romfile>.exe
(*it doesn't necessarily have to be done with a floppy)
Now with this
technique, you can try out new bios files without having to flash
the card itself. If the bios works from the exe file then you would
be sure that it won't mess up your vid card if you flash it. Another
use for this technique is to recover your misflashed video card!
Recovering
from a Failed Bios Flash
It's pretty
much the same as when you are trying out bios files except that you
have to modify a setting in your motherboard's bios. But here's a
step-by-step instruction for to be sure =).
1. Pull out the
misflashed video card
2. Replace the video card with a good one
3. Boot to Windows and prepare the executable bios file and the autoexec
file as noted above. Also prepare a copy of your flashing utility
and the original bios (the one your video card had before flashing)
4. Reboot again and go into your motherboard's bios setup.
5. Turn off 'Halt on Error' (in some motherboards there's an option
to set display adapter to absent)
6. Save settings, exit and shut down
7. Insert the misflashed video card
8. Boot using the autoexec file (it's better to make a bootable disk
that contains the bios file and the autoexec.bat)
Note that the
boot itself would take longer than usual as your computer has to run
the bios file first before you get your display running again. The
most important thing in the technique is to turn off the 'halt on
error' on your motherboard. If you don't turn off the halt on error
then your system won't boot since it can't find your display adapter.
That pretty much
sums it up. Just hope that you won't need this information in the
future. Just remember the two rule of thumbs when flashing. The first
one is, "Always make a backup of your original bios" and
the second is, "When in doubt, DON'T!".
By the way, to
make a backup of your bios you can use dumpbios.
There are two versions of this program, one for 40kb
and 64kb
bios sizes. Just run the exe file and it generates a .bin file for
you.
For any questions,
mail me.
By the way, my
thanks go to Jankees, Fachman
and Juliano (this guy deserves
major credit) for imparting the knowledge required for this artcle.
