VIA Cyrix III/C3

[Mixeur]

I'm currently trying to write a big article on those VIA cpus and I came accross some errors or holes in my database and/or during my web search.

First, regarding the Samuel core, does anyone have the datasheet ? I'm only able to find datasheets from Samuel 2...

Then, about the Cyrix III 800 Samuel (not the Samuel 2 800A). I'm doubtful if it exists or not. Never seen one pictured anywhere. Anyone has one ?

Moreover, are there both FSB100 & FSB133 versions ?
I've only listed FSB100 version on my site, I don't remember why, and not the FSB133 one. On CPU-World, both FSB speed are listed... Who's right ?


Also, on the back of the chip, it seems that we can find information about the stepping, but I don't really know how to decode it.



First numbers seems to be related with cores, like AG20 or A320 = Samuel, AG40 = Samuel2, A350 = Ezra, AG60 = Nehemiah, but what about the rest of the numbers ?

Anyone knows ?

I think it could be very useful to distinguish Nehemiah Stepping 7 and below, from the stepping 8 and above ones, which are actually very different (different die size, different transistor count, different features aso).


Also, John, on your VIA cpu page, you mention C5X & C5XL cores. But from my search, it looks like C5X was never actually released (like C5YL or C5Y or C5Z, actually) :









And at the end, it seems that C5XL = Stepping 0-7 & C5P = Stepping 8-15 acccording to what I read.

=> Correct ?

Thanks.

[crusty_dog]

may help
https://www.cpu-world.com/forum/viewtopic.php?t=18645

additional core ids which are known but not on cpuid list
https://www.cpu-world.com/forum/viewtopic.php?t=19079

[Mixeur]

Sure it helps ! Thanks.
Actually I already read that thread when Neon_WA posted it, but completely forgot since then...
So only third and fourth characters are identifying the core, the 2 first one being for the line or the plant.
Same code for C5XL and C5PL unfortunately...

[max1024]

Mixeur Very interesting Waiting for article )))

[Mixeur]

[debs3759]

I'd be interested in a Samuel datasheet as well if anyone has a link.

[Mixeur]

Anyway, not much answers here. And the more I dig on the web, the more I get new questions...

Especially about Ezra-T. My first thought was that it was not possible to distinguish them from Ezra : physically same, same code with 50, same voltage.
But then, I've seen that some Ezra-T has the 60 code, like Nehemiah : https://www.cpu-world.com/forum/viewtopic.php?p=226870#226870
Also there are AG60xxx C3s with different capacitors layout from Nehemiahs (http://www.x86-guide.net/Xhoba/en/collection/Via-C3-1.0A-(Ezra-T-FSB100)-cpu-no13287.html or http://www.x86-guide.net/Xhoba/fr/collection/Via-C3-1.0A-(Ezra-T-FSB133)-cpu-no11585.html).
So now, I'm in the doubt. Are they really same ? => could the above cpus be Ezra-T ?

Lots of things has been written on the web or in this forum, but most of time without the associated photos so it is quite hard to follow...

[debs3759]

If it helps, according to my data, Ezra and Ezra-T can be detected by CPUID.

Ezra 0678-067F
Ezra-T 0680-0687

I don't know about markings though

[Mixeur]

Yes, already found that : C5C : 0678+, C5M : 0680->0687 & C5N (which is also Ezra-T) : 0688+.
But thanks, I'm feeling less alone.

[Mixeur]

The VIA Cyrix III/C3 article is online :

http://www.x86-guide.net/en/cpu/VIA-C3.html

Let me know if you see errors or missing information.

I did it with what I was able to dig on the net during the past 2 weeks, but still doesn't really know if there is a special package (with 12/12 caps) for those Ezra-Ts...

[Neon]

Thank you for your article - it has lots of good information.

On the second page (Models), under heading 'The Cyrix III', third paragraph, you wrote:
"Models with a 100MHz bus were also released, to be compatible with motherboards that did not have a 100MHz bus..."
This does not make sense to me. I think you meant to write either:
"Models with a 100MHz bus were also released, to be compatible with motherboards that have only a 100MHz bus...", or else,
"Models with a 100MHz bus were also released, to be compatible with motherboards that did not have a 133MHz bus...".

I failed to mention to you that I had another Cyrix C3 ES. It seems to be Ezra C5C 750 (7.5x 100 MHz), however it was easy to run it at 1000 (7.5x 133MHz). CPUID 678 1.35V back cover marked A350EJ0 Pictures are here:
http://cdn.cpu-world.com/Images/uploaded/0000/95/L_00009592.jpg
http://cdn.cpu-world.com/Images/uploaded/0000/95/L_00009593.jpg

[Mixeur]

Yes I meant "Models with a 100MHz bus were also released, to be compatible with motherboards that did not have a 133MHz bus...". Corrected. Thank you very much !

I added the C5C 750 in the database. Very very rare !