Re: P5WD2P/ Microcode Updation
- From: "jeff" <jeff@xxxxxxxxxxxxx>
- Date: Mon, 28 Aug 2006 20:42:24 -0400
Paul,
To say you have an understanding of the most technically challenging
dilemmas would be an understatement, you're a genius.
jeff
"Paul" <nospam@xxxxxxxxxx> wrote in message
news:nospam-2808062032040001@xxxxxxxxxxxxxxxx
In article <VZDIg.4$HH5.2@xxxxxxxxxxxx>, "Jeff" <jeff@xxxxxxxxx> wrote:
I'm still suffering from a temporary cpu swap between a 940D and 840D EE
that now has rendered the 840EE based MB very slow at bios post.
Could microcode and all the swaps have reprogrammed the CPU?
Is there a way to get the CPU back to its original Manufactured stae?
Jeff
Microcode is used to patch the operation of the processor. Each
time you get an updated BIOS from Asus, Asus has the opportunity
to get the latest microcode patches from Intel and incorporate them
into the BIOS. The microcode update is checksummed, and only a
microcode update designed for the particular processor (family
code and version), will be accepted by the processor. So effectively,
Asus cannot touch the contents of the microcode, but only pass
on what they get from Intel.
The microcode is stored in a RAM inside the processor. The RAM
is volatile, and each time the computer is powered off (or even
in S3 standby), the contents of the microcode RAM are lost. The
microcode is reloaded each time by the BIOS code at POST. The
microcode must be loaded early in the POST, in case there is
an error in the processor operation that would prevent the
BIOS POST and boot sequence from completing.
WinXP also has a microcode loader. It is possible for WinXP
to have a later microcode update than the one in the BIOS (if
the user has never updated the BIOS chip), in which case WinXP
would load its microcode into the processor. But that would
happen just before the Windows desktop appears on the screen
(i.e. as all drivers are initializing hardware, in Windows land).
In terms of returning a machine to manufactured state, that would
require:
1) Flashing the BIOS, including the boot block, ESCD/DMI, and
main code module. Basically the whole file gets flashed to
the chip. Say you boot from an MSDOS floppy. You flash the
file you want into the BIOS. Without rebooting, you
immediately reenter the BIOS tool, and make a backup copy
of what you just flashed. Later, compare the backup copy
of the BIOS image, to the file you used to flash. That will
tell you if every bit of the previous version was removed.
The reason the backup has to be that immediate, is after the
BIOS POSTs for the first time, the DMI and ESCD are rewritten,
so the BIOS image no longer exactly matches the file you flash
with.
2) Erasing the CMOS. Unplug computer, remove CMOS battery,
use the CLRTC jumper. Wait. Then reinstall CMOS battery,
plug in computer. Immediately enter the BIOS. Is the
computer clock in the BIOS reset to a bogus date and
time ? If the RTC gets reset, then the CMOS memory should
also be reset.
There are plenty of other non-volatile places for information
to be stored, but only a virus designer would think of them
or use them. Any add-in cards could have their owh BIOS chip
onboard, and add-in cards have their BIOS code loaded at
POST. The video card, for example, can have a BIOS chip. But I
see no reason to suspect you've modified anything in your machine
but items (1) and (2) above.
Paul
.
- References:
- P5WD2P/ Microcode Updation
- From: Jeff
- Re: P5WD2P/ Microcode Updation
- From: Paul
- P5WD2P/ Microcode Updation
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