Re: Disassembling/Debugging the PC's BIOS?

jonfaquit@xxxxxxxxx wrote:

I have a normal pc desktop machine with a msi k8t neo-v motherboard
which utilizes an AMI BIOS. I have a pci video card in an expansion
slot. On bootup POST, the BIOS complains about a routing table error on
device 0:05:00 which pionts to my video card (the only PCI device in an
expansion slot). This motherboard does not have onboard video so I need
this video card in order to see anything (as I do not have any
backups). This video card works flawlessly in another machine
(different mobo/chipset/bios). I have done some searching and it seems
I need to look for a "pnp os" setting in my BIOS; none exists (or the
the mobo manufacturer has conveniently removed the ability to alter
this setting as a lot of them do to a stock BIOS).

So I've come to the point where I want to disassembly/debug my BIOS to
see what the exact error is. I can use dos debug to find the location
of the '$PIR' signature of the routing table and maybe will only have
to analyze the data and this will show what the inconsistency/error is.
Otherwise I need to do some really-involved disassembly/debugging.

The video card still works, however very slowly. It's like it's
"painting" row by row....very obvious to the human eye. CPU utilization
runs up to 90% for a simple act like scrolling a ms-windows notepad
window (and takes a couple of seconds). The card itself is a 5volt PCI
ATI Rage Mobility card (mobo supports 3.3 & 5 and AGP up to 3.0).

I've reset CMOS, removed/reinstalled battery, disconnect power chord
from psu, disconnect all connections to the mobo including the atx PSU
connector, reseated the video card in all slots, removed/reinstalled
the cpu (which isan AMD Athlon 64 @ 2.0Ghz, 200MHz HTT x4 = 800MHz
FSB), tried different memory (current is 512MB ddr400 [200Mhz bus], and
even booted up with only memory, cpu, psu, and video card hooked up and
still same error.

Any tips/pointers?
The BIOS has problems assigning interrupts to the Board. Have you tried the
VGA board in other slots? (Ok. you had, overread it) It may be that the
VGA board has faulty PCI configuration space and it's not the Mobo's fault.
Check the traces on the PCB, which lead to the PCI- INTA, INTB, INTC, INTD
contacts. If more then INTA is used (I.e, boards uses more than one
interrupt, which is quite uncommon these days) it may get difficult. IIRC
"PnP" refers to legacy ISA PnP. PCI is plug-and-play by default.
Try to use an AGP board in addition to the PCI board. Start someting like
Knoppix (Linux on a DVD) and diagnose the PCI bus using lspci.


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