Thinkpad R40 adding Pentium-M Dothan support

[Fry]

Hello. I understand that Thinkpad R40 is very old computer but doing this mod is like getting unicorn.

SO This is 2897-83U system build upon 855PM chipset and initially shipped with SL6N4 Pentium-M Banias CPU. There is no official support for Pentium-M Dothan CPUs for this Thinkpad, but elder brother Thinkpad T40 got support for Dothan CPUs after some BIOS upgrade.

BIOSes:

R40 last official BIOS is 1.33 can be downloaded here (non-diskette version preferable - can be opened with 7zip and inside IMG-file is $018D000.FL1 BIOS file):

https://thinkpads.com/support/Thinkpad-D...uj25us.exe


and diskette version:

https://thinkpads.com/support/Thinkpad-D...uj25ud.exe


For T40 - latest BIOS is 3.23 and can be downloaded here:

https://thinkpads.com/support/Thinkpad-D...uj37us.exe


WARNING This links of official BIOSes but not from official WebSite!

Some more info:

When i put Dothan CPUs SL7EN or SL8QZ notebook starts up but screen remains black and last POST code is 0x32. POST can't finish.
From changelog of T40 BIOS it is seen that addition of Dothan CPU most certantly take place between version 2.13 and 3.00.

I have already mod BIOS adding microcodes for 6D6 and 6D8 CPUs but it can't help.
What to check next?

[DeathBringer]

Post a screenshot of Mainboard tab of CPU-Z with supported CPU installed.

[Fry]

installed.
Ok - asked screenshot + working CPU.
   

PS
CPU-Z shows that it 855GM (I thought that it 855PM + Mobility Radeon 7000).

In addition - my modded BIOS with added microcodes of Dothan CPUs:

  MiMod_WithMicrocodes.zip (Size: 629.15 KB / Downloads: 3)

[DeathBringer]

Can you test your Dothan CPUs (SL7EN and SL8QZ) with other laptop and post screenshots of main tab of CPU-Z?

[Fry]

Sorry for delay. I have found T40 with 3.23 BIOS installed and begin CPU torturing
Yes, i have bad feelings that SL7EN or SL8QZ is not workable - so checking these CPUs and checking their IDs to ensure that i have updated right microcodes was the right thing.

First of all i remember that it was Work In Progress for FSB 533 (BSEL) mod and when i begin work it have CeleronM 370 working at 2GHz
   

Ok i have swapped CPU to 745a (SL8QZ) and got this:
   
It is working but working on lowest multiplier x6 at 133 fsb. With RMC i can push it to higher mult (ex. at x16 i ve got 2.1G but do not do stability tests).

So i undone BSEL mod and got this:
   
x6 at 100 fsb = 600MHz

The result is pretty interesting, but very dump. This T40 have original (or slightly modded not by me BIOS - no WL check + SLIC) with original microcodes. C0 stepping in 745a and other 533 fsb Dothans is not intended to be used in T40 - and this was the dead end of that BSEL mod i was doing some years ago. Now i can replace microcodes like i've done in R40 and see what it say.

The last screenshot is 745 (SL7EN):
   

It works flawlessly and CPU IDs of SL7EN or SL8QZ is correct. So in R40 we should find and patch other thing that blocking POST after 0x32 step...

[DeathBringer]

Try to flash my mod. At first test with SL7EN

[Fry]

Tested (with SL7EN) but still black screen and 0x32 post code).
I read disasmed bioscode2 module - and it should help - modified AND mask treats 6D6 and 696 like the same but haven't worked.

One thing that i have changed (may be should not). I have checked (and updated) your BIOS (1PET65WW_mod.zip) checksum with Endeer phnxcksm.exe utility before flashing.

[DeathBringer]

You need to flash my mod without any changes.

[Fry]

I know that BIOS modding is not for faint of heart.

Phlash16 give me this error with unchanged modded BIOS:
BIOS file maybe corrupt. Extended checksum is not zero. Continue anyway?

(With BIOS corrected by phnxcksm.exe there is no such error.)

Are you sure this is non fatal error?

[DeathBringer]

Upload my mod with corrected checksum.