Hardware Reference
In-Depth Information
On some systems, leaving additional external drives connected prevents a BIOS upgrade from
working properly. Before you start the flash BIOS upgrade process, disconnect all USB and
IEEE 1394 (FireWire) devices except for your keyboard and mouse. If you are booting from a
USB flash drive to perform the upgrade, make sure all other USB drives are disconnected.
If you have Byte Merge enabled in the BIOS Setup on an Award BIOS-based system, disable
this feature as a precaution before you perform the BIOS upgrade. This is recommended
because on some older systems, leaving Byte Merge enabled during a BIOS upgrade can cause
the upgrade to fail, corrupting the BIOS in the process. You can reenable this feature after you
complete the upgrade. Some BIOS upgrades contain fixes for this problem so it can't happen in
the future.
Emergency Flash BIOS Recovery
When you perform a flash BIOS upgrade, you should normally see a warning message onscreen
similar to the following:
The BIOS is currently being updated. DO NOT REBOOT OR POWER DOWN until the
update is completed (typically within three minutes)...
If you fail to heed this warning or something interrupts the update procedure, you can be left with a
system that has a corrupted BIOS. This means you will not be able to restart the system and redo the
procedure, at least not easily. Depending on the motherboard, you might have to replace the flash
ROM chip with one that was preprogrammed by the motherboard manufacturer. This is an unfortunate
necessity because a motherboard is nonfunctional until a valid ROM is present. This is one reason I
still keep my trusty ROM burner around; it is useful for motherboards with socketed flash ROM
chips. In minutes, I can use the ROM burner to reprogram the chip and reinstall it in the board. If “you
need a ROM programmer, I recommend the EPROM+ from Andromeda Research Labs
(
www.arlabs.com
)
.
In most systems, however, the flash ROM is soldered into the motherboard so it can't be easily
replaced, rendering the external reprogramming idea moot. However, this doesn't mean the only way
out is a complete motherboard replacement. Some motherboards have two ROM chips, with the
ability to switch to the second one if the first is corrupted. Other motherboards with soldered-in flash
ROMs have a special BIOS Recovery procedure that can be performed, which restores the contents
of the chip. This hinges on a special protected part of the flash ROM that is reserved for this purpose,
called the
boot block
. The boot block holds a recovery routine that you can use to restore the main
BIOS code.
Note
Because of the small amount of code in the boot block area, onscreen prompts are not usually
available to direct the procedure. This means that during the procedure the screen remains dark
—as if nothing is happening. The procedure can instead be monitored by listening to the
internal speaker or looking at the access LED on the drive containing the upgrade media.
Normally the procedure causes the system to beep once when it begins and several more times
when it ends. During the procedure, you should be able to observe drive activity, indicating
that the BIOS image is being read from the drive and written into the flash device.
