At 18:10 07/19/05, Roberto Safora Romay wrote:
>I have tried and retried to get a bios update for an old PIII
>socket 370 mobo labeled FRU61H2533, from  IBM PC Aptiva.
>Surfing the ibm/lenovo web site didnt get me to the update.
>I changed the CPU to a PIII 866 and when you start the pc a
>message warns that no cpu bios update was found.


Hi Roberto

The message "no cpu bios update was found" means that your BIOS did
not contain the microcode update for the stepping (revision level)
of your PIII processor. (Stepping does not mean a new speed, it
means some small change in the design of the processor itself.)

All processors contain design defects or errors. Previously, the only
way to fix a processor bug was to work around it or replace the chip
with one that had the bug fixed. Now, a new feature built into Intel
P6 processors, (Pentium Pro, Pentium II, Pentium III, etc.) can allow
many bugs to be fixed by altering the "microcode" in the processor.

Microcode is essentially a set of instructions and tables inside the
processor that control how the processor operates. These processors
incorporate a new feature called "reprogrammable microcode", which
allows certain types of bugs to be worked around via "microcode
updates". The microcode updates reside in the system ROM BIOS and
are loaded into the processor by the system BIOS during the power on
self test (POST). Each time the system is rebooted, the fix code is
reloaded, ensuring that it will have the bug fix installed anytime
the processor is operating.
<http://www.informit.com/articles/article.asp?p=130978&seqNum=22&rl=1>

For each new stepping PIII released by Intel, the motherboard
manufacturer should release a new system BIOS that contains the new
microcode update (an errata) for that stepping. If the manufacturer
stopped supporting your motherboard before Intel stopped releasing
new steppings of PIII, and you get a new processor, you'll have to do
without the microcode update for your processor and hope that any
resulting problems are so minor as to be negligible.

Obviously "no cpu bios update was found" message does not appear on
every computer. It could be that a message like "microcode update
applied" was on screen for such a short time that it was not
noticeable. Or it could be that the microcode update routine was
unwittingly disabled in BIOS Setup.

Regards,
Bill

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