BIOS backup problem

Recommended by Wim's BIOS...

by **arios** » Mon Sep 22, 2003 10:36 am

I have a problem about BIOS backup. :?:

When I update the BIOS and backup after change the device like storage device, pci card...etc,
I found the backup file will be different.

I want to know if the BIOS content will be changed when the devices on M/B are different...

Can anybody answer me, and thanks in advance !!!

by **NickS** » Mon Sep 22, 2003 1:21 pm

When you add/remove devices, the information in the "DMI pool" is updated. The DMI Pool contains information about the PC's configuration which can be used by other programs. The DMI pool is held in the BIOS ROM, so changing the configuration partially reflashes the BIOS with changed information, which will affect the BIOS checksum.

by **arios** » Tue Sep 23, 2003 4:08 am

Thanks!! NickS.

I have another question. When I add/remove devices, and backup the BIOS ROM, does the BIOS ROM content will be changed?
( there isn't any BIOS reflash action )

Thanks in advance !!

by **NickS** » Tue Sep 23, 2003 10:12 am

When you add/remove devices, the content of the area of BIOS ROM used for the DMI pool will be changed. This is a mini-flash which you don't even know is happening except that the screen says "Updating DMI" or "Updating configuration data" at the configuration screen (the one after the memory test screen). When the content of this area is changed, the content of the whole BIOS ROM is changed.

When you backup the BIOS it will contain the DMI information about your current configuration so it will differ from a backup you took with a different configuration.

by **arios** » Thu Sep 25, 2003 1:59 am

Thank you, NickS.

Now I understand. ^^

However, I have a question about "DMI pool".
I know that BIOS ROM contains DMI information (DMI pool), but which part does the DMI pool locate in the BIOS ROM? ( For example, If there is a 4M bit BIOS falsh rom, the DMI pool is located in ????byte to ???? byte. ) Is it's location will be change with the different BIOS manufacturer (IBM, AMI or AWARD)? or the location of DMI pool in BIOS ROM is the same for every BIOS.

Thanks for your kindly reply!!

by **Rainbow** » Thu Sep 25, 2003 9:45 am

The location depends on the chip size (128KB/256KB/512KB). If the chip has sectors, the DMI and ESCD is located in a parameter sector (because the sector must be erased before it can be programmed again).