Editing Thinkpad R40 CPU Microcode for Dothan CPU support

[Thinkman0512]

Hi guys,

I really want to make Dothan CPU's work in my R40, and I think that by editing the CPU Microcode in the bios, I could make this work. The only issue is, I've got not clue how to do this. I know this is possible, because I've heard of at least one forum member who has done this succesfully, but I can't remember his name, and I don't think he had uploaded his patched bios to the forum, if I remember it correctly. Does anyone know how to do this?

[t43_guy]

Hi, unfortunately what you wish to do is not possible, the ThinkPad R40 uses Pentium 4-M CPUs with the Intel i82815 chipset, and while the CPU socket is the 479 which is mechanically compatible with Pentium M Dothan CPUs, the system isn't because Dothan CPUs are designed to work with the 82855 or 82915 chipsets found in newer thinkpads such as the T43, R50 and R51.

You may be referring to installing a Dothan CPU on an R50 which uses the 82855 chipset, that is actually possible with no modding at all but your CPU will be limited to 100 MHz FSB frequency because that's what that chipset is rated for. So yes you can perform this latter mod but your CPU will run slower than usual.

[Thinkman0512]

Hi, unfortunately what you wish to do is not possible, the ThinkPad R40 uses Pentium 4-M CPUs with the Intel i82815 chipset, and while the CPU socket is the 479 which is mechanically compatible with Pentium M Dothan CPUs, the system isn't because Dothan CPUs are designed to work with the 82855 or 82915 chipsets found in newer thinkpads such as the T43, R50 and R51.

You may be referring to installing a Dothan CPU on an R50 which uses the 82855 chipset, that is actually possible with no modding at all but your CPU will be limited to 100 MHz FSB frequency because that's what that chipset is rated for. So yes you can perform this latter mod but your CPU will run slower than usual.

Thanks for your reply. The R40 does in fact use Pentium M's, but only a few specific models of R40, of which I have one. As for the chipset issue, I don't really care about speed, it's more about full NX-bit support for me, and also, it's really just an experiment for me to see if I can get it to work.

[t43_guy]

Oh I'm sorry, I was mistaken, after all my area of expertise is the T series :p

I read up on thinkwiki about the R40, there are models which use Pentium M CPUs and the 82855 chipset, and models which use Pentium 4-M CPUs and the 82845 chipset.

If you have that model which supports Pentium M Banias chips then yes you can just install a Dothan CPU and it will work but at 100 MHz FSB. I want to eventually get into BIOS modding myself at some point, this is a matter of inserting the microcode into the BIOS blob at the right place, although that's pretty much all I know, I think you can find the microcode for intel CPUs on certain linux packages. But yeah your best bet is to search around the forum for the old post you mentioned where someone published a BIOS with support for Dothan CPUs. There were people interested in the same thing but on the T40, looking for that may help too.

[RealBlackStuff]

Don't forget that R40 is not even a Thinkpad!
It's a POS made by Acer, 'upgraded' with an IBM sticker.

[Thinkman0512]

Don't forget that R40 is not even a Thinkpad!
It's a POS made by Acer, 'upgraded' with an IBM sticker.

Do you know what? I really think that isn't fair. I mean, it might not have been made by IBM, but it's certainly as sturdy as my T60(which, in all fairness, wasn't made by IBM either). Really the only thing I can complain about is the slight amount of keyboard flex the R40 has.

[kfzhu1229]

Do you know what? I really think that isn't fair. I mean, it might not have been made by IBM, but it's certainly as sturdy as my T60(which, in all fairness, wasn't made by IBM either). Really the only thing I can complain about is the slight amount of keyboard flex the R40 has.

It's most probably the price really. The R40 was cheap by IBM's standards when new, and also since most of the work was done by Acer, IBM probably did not feel like the need to treat it well with Dothan capability. If this were a full Acer laptop it would've added Dothan support for sure.
As for the sturdiness, Acer Travelmates back then weren't bad in build quality either
There is also the question of whether the hardware itself has fatal problems preventing a Dothan CPU from working. There are some odd Core 2 duo laptops, like the Dell Latitude D530, that had a hardware flaw that prevents a Penryn CPU from working - even if you inject Microcode, as BIOS-mod websites tried, it still wouldn't work.

[axur-delmeria]

As for the sturdiness, Acer Travelmates back then weren't bad in build quality either

I disagree with that, having DIY'ed hinges for a Travelmate 512DX: https://www.flickr.com/photos/axur-delm ... 2988060536.