Hardware Reference
In-Depth Information
If the diagnostic status byte is any value other than
0
, you typically get a CMOS configur-
ation error on bootup. You can clear these types of errors by rerunning the setup program.
Year 2000 BIOS Issues
Allsystemsnowinuseshouldbecompliantwithtwenty-firstcenturydates,eitherthrough
BIOS updates or through software or hardware patches. However, if you are returning to
service stored systems built before 1999, you might want to test them for year-2000 com-
pliance.
Preboot Environment
Some systems use the Phoenix BIOS preboot environment, which has a graphical user in-
terface(GUI)thatallowsausertoaccesstheBIOSSetup,extendeddiagnostics,abackup/
restore application, or a full recovery of the original system contents (product restoration
to factory-delivered contents). All these applications (except the BIOS Setup) are stored
in the
HPA
(
Host Protected Area
), a hidden area of the hard drive literally situated past
the reported end of the drive. The number and type of applications accessible via the pre-
bootenvironmentdependonwhichoptionstheOEMselectedwhendesigningthesystem.
Figure 5.8
shows the IBM/Lenovo implementation of the Phoenix BIOS preboot environ-
ment. This environment is activated by pressing the Enter key on the keyboard during the
POST.
Figure 5.8
IBM/Lenovo implementation of the Phoenix BIOS preboot environment.
