Common errors associated with the BIOS
include CMOS checksum errors, IRQ/DMA conflicts, hard drive errors,
memory errors, and CPU problems. Table
provides
common errors that might be received by the computer operator.
The BIOS is a good place to start diagnosing hardware problems. The features of BIOS provide technicians
with low-level hardware and software configuration information.
Although the BIOS provides low-level information, it is extremely
useful when troubleshooting computer hardware. The average computer
problem will be a simple fix. Most end users are not aware of BIOS
information or else they do not know how to interpret it, so it is
rarely used effectively while troubleshooting. However, the BIOS
should always be used for troubleshooting hardware problems. Common
CMOS errors are included in Figure
.
The Complementary Metal Oxide Semiconductor
(CMOS) or Non-Volatile Random Access Memory (NVRAM)
stores the systems startup configurations and parameters.
Accessing the CMOS
To access the CMOS setup utility, press the setup key during the
boot process. The setup key must be pressed early in the boot process,
or the system will load the installed OS. The CMOS setup key is
usually F1, F2, or Delete. However, there is no standard, so verify
the setup key with the proper documentation. If the video display is
functional, a prompt to enter setup by pressing a certain key is
usually displayed. Pay attention to the CMOS messages for the setup
key to push to enter the CMOS startup utility. Figure
shows a common CMOS Setup utility.
Identifying the Faulty/Incorrect CMOS Setting
One way to help resolve CMOS related errors is to reset the defaults
to the CMOS settings. Resetting the CMOS clears the memory and all
potential corrupted data. Clearing the CMOS memory is useful when the
computer will not boot at all. There are two ways to clear the CMOS
memory. The easiest way is to remove the CMOS battery (the small round
battery on the motherboard
)
as follows:
| Step 1
|
Turn off the power on
the computer.
|
| Step 2
|
Remove the CMOS
battery from the motherboard.
|
| Step 3
|
Short the negative and
positive connections (terminals) of the battery location on the
motherboard, using any conducting material (wire, screwdriver
head, and so on). Shorting removes any residual capacitance
(accumulated charges).
|
| Step 4
|
Replace the CMOS
battery in its original position on the motherboard.
|
| Step 5
|
Turn the power on
(reboot) the system.
|
If the above procedure fails to clear the CMOS, consult the
motherboard documentation for the location of the CMOS jumpers. After
locating the CMOS jumpers, they can be moved to the "Clear CMOS
position" for a few seconds to clear the CMOS memory.
Upgrading the BIOS
A BIOS upgrade can include patches, fixes, additional features, and
additional support for the latest devices that should resolve any
problems. However, it is not recommended to upgrade the BIOS if
problems do not exist. If the system is operational, BIOS upgrades are
risky and should be avoided. If the BIOS is updated incorrectly, it
could damage the motherboard and peripheral devices.
Special consideration must be taken before upgrading the BIOS. The
motherboard is required to have flash BIOS, and it must support the
upgraded version. The BIOS chip also needs to support the upgrade
version number. Only when these criteria are met can the BIOS be
successfully updated.
Always obtain this information before attempting a flash BIOS
upgrade. Generally, if the motherboard has PCI slots, it has flash
BIOS. The BIOS revision number should display during startup. It will
be in the format #401A0-1234. In this example, the revision number is
1234. It is the number that appears after the dash (-). The
motherboard revision number will be printed on the motherboard. In
newer motherboards, the revision number is located near the CPU or
center of the motherboard.
In order to upgrade the BIOS using flash, follow these general
steps:
| Step 1
|
Save the flash upgrade
utility to a blank floppy disk. The disk should contain the BIOS
update utility (flash.exe or awdflash.exe) and the motherboard
binary file. The motherboard binary file will have a .BIN
extension.
|
| Step 2
|
Reboot the computer to
the floppy (A:\) drive. At the A prompt, type: awdflash file.bin.
Note: The file.bin is the
filename of the revision that was downloaded. Then, press
Enter.
|
| Step 3
|
Save the old BIOS
file. The utility will then prompt you to save your old BIOS to
file. It is always recommended that the old BIOS setting be saved.
In the event that the technician has to reverse the
changes, the backed up BIOS file can be used.
|
| Step 4
|
Run the BIOS upgrade
utility. Next, the utility will ask for a BIOS update
confirmation. The technician will be required to press
"Yes" for confirmation.
|
| Step 5
|
Restart the computer.
More specific steps related to a particular BIOS is available on
the manufacturer website or motherboard manual. Additionally,
some of the newer motherboards support web updates. |
