ok I after many attempts I think I am making some progress, but not to sure why at the moment. I will need to go back over the changes I have made and see if it is any one thing that has made it work.
The memory check passes up until A0000. I am assuming as this is resrvered for the VGA controller it is to be expected.
I have compared northbridge register dumps of both my epia boards, rev A and D but can see no difference, so I don't think there have not been any changes to the northbridge.
One difference between original bios and linuxbios is register 0x67. According to the datasheet it is reserved. However booting with the original bios this register contains 0xc4 and 0x00 with linuxbios. I am currently setting it to 0xc4 but not sure yet if that is why I have some success. I have made a few changes, while comparing the V2 to V1.
Anyway I am now getting as far as running filo but have another problem. This is what I get
Setting fixed MTRRs(0-88) type: UC Setting fixed MTRRs(0-88) Type: WB DONE fixed MTRRs call enable_fixed_mtrr() Setting variable MTRR 0, base: 0MB, range: 256MB, type WB ADDRESS_MASK_HIGH=0xf
Unexpected Exception: 13 @ 10:00008891 - Halting Code: 0 eflags: 00010006 eax: 00000300 ebx: f0000800 ecx: 0000da00 edx: 0000000a edi: 0000da00 esi: 0000000f ebp: 00017ee0 esp: 00017ebc
Perhaps someone could explain this to me.
By booting from the original bios and resetting mid-boot and switching to linuxbios filo has got to the stage of looking for my kernel image although it couldn't find it (maybe bad typing on my part).