AMD Radeon Bios disassembling

[FeeJay]

Hi to everyone.

I want to disassemble a AMD Radeon Bios to learn something about modding.
I used atomdis, the AMD Atombios dissassembler, but it offers nothing about PCIR and Device ID.
My Bios is the XFX R7 260X 2048 MB you can download it here http://www.techpowerup.com/vgabios/14986...31029.html

I changed:
offset 0x00007 from 00 to 0F
offset 0x0025A from 58 to 49

Atiflash shows that my Device ID will be changed from 6658 to 6649 but after restart the old 6658 device ID was back at offset 0x0025A

I uploaded the Bios to ODA online disassembler and it shows me BIOS (ia32) ROM Ext. IBM comp. Video (128*512)

Can somebody help me to disassemble the PCIR part?