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First post, by WJG6260

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Hello all,

I know this sounds like a foolish question, but I've been looking around here and there and have never seen a Cyrix DX-50 CPU. There's a few references out there to this particular CPU, namely on x86-guide here and on CPU-World here.

From what I understand--and from my personal experience--the Intel DX-50 is pretty fast, but the added wait states from the 50Mhz bus are somewhat disadvantageous when building such a system, especially if the motherboard is not up for the task of a 50Mhz bus. It seems like a well-tuned DX2-66 is just an all-around simpler, faster, and easier choice.

Cyrix 486s are another subset of oddities, in the sense that their off-cache accesses are quite fast, and their ALU performance is slightly less than that of their Intel/AMD counterparts. Their FPUs seem a little stronger though, at least from my rudimentary comparison of a 5V Cyrix DX2-80 to a 5v Am486DX2-80.

To that end, then, is it safe to presume that the Cyrix DX-50 is somewhere around an Intel DX-33 or AMD DX-40 in terms of sheer performance?

I feel like I've read something to the extent that the early Cyrix 486s post-Fascache models (Is it "M6," for the full 8k cache Cx486DXs?) had heat issues, and that's why the 4.0V and 3.6V models are more common, as they supplanted those earlier, hotter models. Is the Cyrix DX-50 then a pretty rare bird?

Thanks for the input, and I hope you all had a wonderful holiday and New Year!

-Live Long and Prosper-

Feel free to check out my YouTube and Twitter!

Reply 1 of 10, by debs3759

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Cyrix DX50 is pretty rare, yes. It definitely exists, or those two reputable collectors couldn't and wouldn't have posted separate photos of it. Never seen one for sale, and I've been watching sales on CPU-World for well over a decade. Can't comment on integer or FP performance yet though, as I've not done my own tests (hope to get round to testing a few 486 boards and a broad selection of CPUs this year).

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

Reply 2 of 10, by WJG6260

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I see, that definitely makes sense. I figured insofar as that those collectors' photos were evidence of its existence, but have been wondering why they're so elusive; it seems as if the Cyrix DX-50 is up there in rarity with some of the true oddities of the 486 world like the UMC U5SD or Cyrix 5x86-133.

I can't lie that it's elusiveness definitely contributed some to my skepticism there.

Do you think that a Cyrix DX-40 might be able to cope with such an overclock, just to see the performance delta between that and an Intel DX-50?

Thanks for your thoughts, I really appreciate them! 😀

-Live Long and Prosper-

Feel free to check out my YouTube and Twitter!

Reply 3 of 10, by debs3759

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As long as it has a heatsink, I see no harm in trying to boot it at 50MHz. I certainly will be trying all my 486 at higher clocks, just to see which can cope.

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

Reply 4 of 10, by Anonymous Coward

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I've definitely seen the Cyrix DX-50. I always found it amusing that Cyrix ever bothered with these. The Intel version was never that popular outside of engineering and academia, and seeing as how the market for the DX-50 was already basically dead in 1993 it didn't make any sense to clone it. I Could be mistaken, but didn't AMD also have a DX-50?

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 5 of 10, by WJG6260

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I won’t lie, the fact that Cyrix even considered a DX-50 intrigued me, and that’s really what prompted me to inquire. I feel as if the Intel DX-50 has a (somewhat deserved?) black sheep status amongst its peers and I figured a Cyrix equivalent would be even more interesting.

I can’t say I’ve seen an AMD DX-50, but that would be interesting! I wonder what stepping it’d have been, and on what process node it would have been fabbed? Perhaps it’d have shared a process with the early 5V DX2-80s and DX2-66s?

Out of curiosity, was there ever a Cyrix v50, as in a 3.3V DX-50? Now that would be an interesting CPU.

-Live Long and Prosper-

Feel free to check out my YouTube and Twitter!

Reply 6 of 10, by Anonymous Coward

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I just looked into it. AMD had the 40MHz DX, but sadly no 50.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 8 of 10, by debs3759

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Grzyb wrote on 2022-01-05, 09:13:

Any evidence of those Cyrix DX-50 chips actually being available on the market back in the era?
Or was it just prototypes?

The two links in the original post show production models. Very uncommon though, I'd not heard of them before.

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

Reply 9 of 10, by rmay635703

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debs3759 wrote on 2022-01-05, 09:33:
Grzyb wrote on 2022-01-05, 09:13:

Any evidence of those Cyrix DX-50 chips actually being available on the market back in the era?
Or was it just prototypes?

The two links in the original post show production models. Very uncommon though, I'd not heard of them before.

Occasionally would notice them in the “big lists” of prices in the Computer Shopper usually with an ISA motherboard.

They arrived comparatively late and never made much sense to me, my guess is most folks felt the same so sales were low

Reply 10 of 10, by WJG6260

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Anonymous Coward wrote on 2022-01-05, 07:58:

I just looked into it. AMD had the 40MHz DX, but sadly no 50.

I see. Interesting. That probably makes sense, as the AMD DX-40 was not exactly the most well-regarded chip, by all accounts I’ve read.

rmay635703 wrote on 2022-01-05, 15:12:
debs3759 wrote on 2022-01-05, 09:33:
Grzyb wrote on 2022-01-05, 09:13:

Any evidence of those Cyrix DX-50 chips actually being available on the market back in the era?
Or was it just prototypes?

The two links in the original post show production models. Very uncommon though, I'd not heard of them before.

Occasionally would notice them in the “big lists” of prices in the Computer Shopper usually with an ISA motherboard.

They arrived comparatively late and never made much sense to me, my guess is most folks felt the same so sales were low

This makes sense to me. I pretty much figured the same.

I wonder if any of the early, high-end EISA 486 boards supported this CPU properly. That would be a pretty neat combination, and at least the 50MHz bus wouldn’t be much trouble on an EISA board.

-Live Long and Prosper-

Feel free to check out my YouTube and Twitter!