Hardware Reference
In-Depth Information
start the system and redo the procedure, at least not easily. Depending on the mother-
board, you might have to replace the flash ROM chip with one that was preprogrammed
bythemotherboardmanufacturer.Thisisanunfortunatenecessity becauseamotherboard
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. Most motherboards with
soldered-in flash ROMs have a special BIOS Recovery procedure that can be performed,
whichrestores thecontents ofthechip.Thishingesonaspecial protected partoftheflash
ROM that is reserved for this purpose, called the
boot block
. The boot block holds a re-
covery routine that you can use to restore the main BIOS code.
Note
Becauseofthesmallamountofcodeinthebootblockarea,onscreenpromptsarenotusually
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 me-
dia. Normally the procedure causes the system to beep once when it begins and several more
timeswhenitends.Duringtheprocedure,youshouldbeabletoobservedriveactivity,indic-
ating that the BIOS image is being read from the drive and written into the flash device.
Different motherboards and BIOS versions may have different recovery techniques. Most
motherboards (including those from Intel) that support BIOS recover incorporate a BIOS
configuration jumper, which can set several modes, including a built-in recovery mode.
Figure 5.7
shows this jumper on a typical motherboard.
Figure 5.7
BIOS configuration jumper.
