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Cyrix appreciation thread

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Reply 280 of 298, by shamino

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harddrivespin wrote:
skitters wrote:

Some 486 motherboards had fake cache http://redhill.net.au/b/b-bad.html

Wouldn't that be technically illegal due to misinforming customers (At least in the US)?

I had one of those boards here in the US. It didn't come from a well known retailer though, it came from a small computer shop, which I guess was typical for home building PCs in the mid 90s. I also bought an IDE controller card there once. After those two experiences (neither device was branded, and neither really worked properly), I decided not to shop there anymore. Not sure where they were getting their parts from, but that place was cheap for a reason, apparently.
That article was a revelation for me when I first saw it. I had not known how infamous that board was, but I always hated how unstable it was.
The key differences with my board are that the BIOS was socketed and the chipset's sticky label said "PC Chips" on it - not a forged logo from another manufacturer. Underneath it was still the "8DY" chipset though. To this day I don't know if the cache was fake - I still have the chips but nothing to test them in.

The aforementioned motherboard is the reason I became a Cyrix 6x86 fan and user. In 1996 I saw the Cyrix as an affordable way to upgrade to a faster and much more stable system. It delivered on both counts. 3D wasn't really a thing yet, at least for me. I wasn't aware the Cyrix would be weak in those type of games, and it didn't become an issue until later.

Reply 281 of 298, by swaaye

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How about an ancient Performance Analysis of the 6x86 from some place called MDR Labs?
https://web.archive.org/web/19970607201650/ht … bsr_6x86_3.html

I have been going through some vintage bookmark backups. 😀

Reply 282 of 298, by root42

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Back in the day I upgraded my 486SX 25 (or was it 33?) to a new motherboard. I could not afford a whole new system, but I ripped out the mainboard, VGA and Multi I/O and got a brand new ASUS P55T2P4 with 8 MiB RAM, and a Cyrix 6x86 P166 and an S3 Trio64V+. That was one awesome upgrade! Later, I sold the P166 and replaced it with an IBM MII 233. That was as far as the board would go. Loved that thing... The Cyrix had the nice gold top and the IBM hat the sleek black ceramics on top.

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Reply 283 of 298, by feipoa

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the disk was defragmented between benchmark runs.

Wow, they really took this seriously. This is also quite evident from their sentence structure in general. I'm gonna read this on my iPAD in bed. Makes for some nice get-to-sleep material.

Very interesting how they took results normalised to a Pentium of choice, like how I ran my 486/686 benchmarks.

For the most part, the Cyrix 6x86 beat its "P-rating" score by a few percent.

the 6x86-150 MHz delivered a Winstone 96 score approximately 3% higher than the 200-MHz Pentium and increased its advantage to 5% on Winstone 32.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 284 of 298, by Nemo1985

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kool kitty89 wrote:
I'm not sure about 2.9 vs 2.2v cores in general, but I Cyrix did make modest modifications/tweaks that slightly improved perform […]
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I'm not sure about 2.9 vs 2.2v cores in general, but I Cyrix did make modest modifications/tweaks that slightly improved performance for later revision parts: there's a bit on that mentioned here:
http://www.sysopt.com/forum/showthread.php?t=44340

Not all MII are created equal - rev. 08h is faster than older ones at the same clock speed, rev. 14h is faster again, and even newer ones might be further optimized. The ratings table got changed several times to take this into account.

Also note that the MII was made in both 250 nm and 180 nm as 2.2V parts (and fewer rated at 2.0v -possibly 2.1 as well), though apparently most/all of the PR400 (and 433) chips are 180 nm.

feipoa wrote:
I just noticed something odd regarding the difference between the 2.9 V MII and the die shrunk 2.2 V MII; per-clock, the 2.9 V M […]
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I just noticed something odd regarding the difference between the 2.9 V MII and the die shrunk 2.2 V MII; per-clock, the 2.9 V MII seems to perform 2 - 6% better in benchmarks compared to the 2.2 V version. These results come from Winbench99 CPUmark, Sandra99, and MDK Performance (Software). I didn't bother checking more.

Thinking that I must have changed hardware or some other settings, I re-ran the 2.2 V benchmarks, but they were still 2 - 6% lower than the 2.9 V Cyrix MII. The only MII 2.9 V CPU I have that would run reliably at 3.5 x 75 (262 MHz) was an IBM 6x86MX-333PR, which was the last IBM MII. I am not sure if IBM made any secret mods to their last MII or if Cyrix's die shrunk 2.2 V version had any features removed for the purpose of increasing yields at higher frequencies.

Another idea is that IBM simply changed some of their default register settings for slightly improved performance. I probably should have checked for that before putting the machine away...

The performance also increased in Speedsys, 1% for L1, 13% for L2, and 5% for the RAM. Memory bandwidth is listed as 225 MB/s for both CPUs. I used 3.5 x 75 = 262 MHz for these tests.

Speedsys
Cyrix MII 2.2v ---> IBM MII 2.9v

Score: 187.13 ---> 188.24 (This is probably where the 1% for L1 comes in)
L1: 877.76 ---> 887.48
L2: 196.35 ---> 222.29
RAM: 98.45 ---> 103.11

Puzzling. Does anyone know with any certainty if Cyrix made any technological changes to the 2.2 V die shrunk MII?

I'm testing a Cyrix MII 333GP V2.2 and a Cyrix 6x86MX PR266 V2.7 both at 250 mhz.
I can confirm that the second is faster at the same frequency. Not much difference 45,9 vs 48,1 in quake 320.

6x86:

 CPU Identification utility v1.25                 (c) 1997-2016 Jan Steunebrink
------------------------------------------------------------------------------
CPU Vendor and Model: Cyrix/IBM 6x86MX PR166-266 or Cyrix MII PR300-433
Internal CPU speed : 250.5 MHz (using internal Time Stamp Counter)
Clock Multiplier : 2.5
Bus clock speed : 100.2 MHz
CPU-ID Vendor string: CyrixInstead
CPU-ID Signature : 000600
Cyrix Device Id Regs:
DIR0: 52h -> CPU Model
DIR1: 07h -> CPU Step and Revision
Current CPU mode : Real
Internal (L1) cache : Enabled in Write-Back mode

M2:

CPU Vendor and Model: Cyrix/IBM 6x86MX PR166-266 or Cyrix MII PR300-433
Internal CPU speed : 250.5 MHz (using internal Time Stamp Counter)
Clock Multiplier : 2.5
Bus clock speed : 100.2 MHz
CPU-ID Vendor string: CyrixInstead
CPU-ID Signature : 000601
Cyrix Device Id Regs:
DIR0: 52h -> CPU Model
DIR1: 34h -> CPU Step and Revision
Current CPU mode : Real
Internal (L1) cache : Enabled in Write-Back mode

Reply 285 of 298, by feipoa

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It's consistent then! More benefit to run at lower voltage though.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 287 of 298, by kool kitty89

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I'm not sure it got mentioned yet, but there's been an upload of Winstone 95 since the 686 benchmark results were run (an ISO of it was posted in the Vogons Archive as of 2016) and the Ziff Davis Winbench 95 software package was posted on PCCorner in the last few years, too.

And given those are the tests that predominantly championed Cyrix 6x86 performance, it's interesting to look back at those. I've only run tests with my Asus P5A-B so far (which isn't the fastest for 6x86s/MIIs) but it does seem to back up the relative performance. And I also started doing comparisons with P54 and P55 CPUs at equal clock and bus speeds for more 1:1 comparison (overclocked bus Pentiums is something Redhill didn't touch on). The bit I run, including 2x75 for the 6x86 and P54 still left the 6x86 well ahead, though.

Using the 1x multiplier setting also gets some interesting results that favor some of the Ziff Davis tests and points to some interesting in-era possibilities for early adopters with the 80 or 100 MHz rated parts. (dropping down to 1x 66, 68, or 75 MHz getting a performance boost for a good number of things ... 83 MHz moreso if you had a board capable of it back then, or maybe upgraded to a new board+RAM with an old CPU in 1997)
They don't seem to like 1x100 MHz, though. (the one 80 MHz, PR90 CPU I have still seems to do 1x 83 MHz fine in Win98SE)

I also have an FIC VA-502 now, so I can test Red Hill's claims of unusually good performance with 6x86MX (and presumably MII) chips, particularly their PR200 (166 MHz) configuration, which was supposed to be the fastest general-purpose build they could make at the time.

The only other area that's not been fully explored in retrospect (I think) is the relative gaming performance of Cyrix builds for things other than Quake and most API-driven 3D engines, but ones that were still pretty CPU demanding at the time, even ones a few years old (like 1993-1995 era 3D games with 640x480 SVGA rendering support).

Phill's standard Socket 7 benchmark comparison videos seem to include Wind Commander III's hanger launch sequence for minimum framerates, and is one interesting area to start. He also seems to have found out that faster clocked MX/MII CPUs run too fast for Wing Commander 1 even with all cache disabled, so you need to drop the multiplier or bus speeds down for that (I believe it's too fast by the PR300 range, so 233 MHz).

OTOH, with an earlier S7 board capable of 50 MHz FSB, 1x50 MHz with a 6x86 might work for Wing Commander II without disabling the L1 cache.

There's also the odd case of Tomb Raider, at least for its software renderer, that seems to be fairly heavy on the ALU side and doesn't use a Quake-like FPU-driven pixel pipeline, but does still require an FPU. It might be optimized for 486 DX4s and x5s or something like that, and seems like it's well balanced for the beefy (for 486) FPUs in Cyrix 486s and 5x86s as well as AMD's overclockable 5x86. (I think the AM5x86 also might have a slower ALU than the Cyrix or Intel DX4, or enough that offloading mul/div heavy math to the FPU might even be faster ... though that may be true of most/all 486s if you need 32-bit precision or better: 16-bit integer math has more speed advantages on the 486)

That sort of balance might also carry over well to the Cyrix 6x86 and K5 with their balance of ALU and FPU performance.

Other than Tomb Raider, I'd think most other relevant mid-90s games that might be faster (at least per-clock, if not by PR-number) would be ones released prior to 1996, or at least using engines designed well prior to that. (like late generation Doom or Build engine games, or Rise of the Triad's 32-bit extended Wolf3D engine)

And I'm not positive, but the DOS, CD-ROM version of Tie Fighter might be the most taxing 16-bit real mode game that could be tested, with its 640x480 SVGA mode. (I haven't confirmed that's a real-mode game, but given the engine it's built on and the fact it still requires conventional + EMS memory exclusively, seems to imply that pretty heavily) It's on my list of things to get running on a 286. (I would have already done it if I hadn't been dragging me feet with setting up a CD-ROM driver)

I'm not sure what it takes to max out Tie Fighter (especially in more populated/active scenes) but it might still be relevant for even a Pentium 100-166 class system. And the 6x86 is known for being very fast at 16-bit real-mode operations (and presumably in its Virtual 8086 implementation) so would be a good contender there. Also potentially one of the few areas outside of 3DBench that the 6x86 would vastly outperform the Pentium Pro, or somewhat outperform it at the same PR number.

OTOH, the X-Wing and Tie Fighter games are somewhat well known for their EMS-handler related errors (EMM386/XMS errors), and the original Floppy Disk version of X-Wing is particularly crash prone and speed-sensitive (or video card sensitive) in my experience on a SS7 system (the Tie Fighter and related BWing/XwingCD engines are more stable, but still EMS driver sensitive). So they'd be good tests for stability and, unlike Wing Commander 1 and 2, they're properly frame limited (using some sort of timer interrupt or polling routine) and not CPU-clock dependent, so can be maxed out on fast systems and kept playable.

Reply 288 of 298, by appiah4

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It's weird and sad to re-stumble onto this topic on the day I brought home an MMX-200 to replace my 6x86MX-PR233 because its Quake 1/2 performance was so lacklustre.. Now I feel dirty and I'll probably not do the swap..

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Reply 289 of 298, by mwdmeyer

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Yes I always wondered if the Cyrix would be better than a Pentium for things like Starcraft and other RTS games. I'd need to do some testing at some stage.

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Reply 290 of 298, by appiah4

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mwdmeyer wrote on 2020-04-21, 10:56:

Yes I always wondered if the Cyrix would be better than a Pentium for things like Starcraft and other RTS games. I'd need to do some testing at some stage.

The problem is that while it may be better, Pentium is good enough for those, while Cyrix is not even mediocre at FPU stuff..

Retronautics: A digital gallery of my retro computers, hardware and projects.

Reply 291 of 298, by kool kitty89

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OK, the 1995 Tie Fighter Collector's CD-ROM for DOS uses a 386 Protected Mode engine, so not the same as the 1994 Tie Fighter (floppy) and X-Wing CD engine, though might still be 16-bit instruction heavy. Looking at the system requirements again (8 MB and 486DX2) that change is a little more obvious, where the 1994 releases still say 386DX).

So those 1994 releases would be more relevant, but also less CPU taxing.

... and now I've got to add the floppy disk version of Tie Fighter to my list of games to test.

Reply 292 of 298, by Nemo1985

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Hello people, last time I played with Cyrix SS7 cpus I had an utility that was able to identify the stepping of the cpu and it was saying if it was good, bad or mediocre, now i'm unable to find it again, if I remember right it was a specific dos utility for cyrix, I tried several programs but noone of them did that.

Any help?

Thanks

Reply 293 of 298, by Paralel

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I've run into a interesting Cyrix conundrum recently, but with regards to coprocessors.

Cyrix created a coprocessor that was intended to be used with their 486SLC CPU's, the SLC87. It was offered in a PLCC-68 package just like their Intel 387SX and 387SL counterparts, and numerous other 387 plug-in coprocessors.

However, I came across two oddballs in a batch of SLC87 coprocessors that I haven't been able to find out anything about. They are labeled 87SLC, and have a correct matching part identification, Cx87SLC-25-JP, (the SLC87's are CxSLC87-25-JP) and all the other markings match those found on the SLC87 parts (such as on the back, the copyright markings, and the two digit number in the upper right circle, and the word KOREA in the lower right circle). The only difference between the two oddballs and the typical SLC87 parts is when they were made. All the SLC87 parts were made between the 6th week of 1992 and the 17th week of 1992, but the two oddballs were made in the 28nd week of 1992.

Interestingly Cyrix made an 87SLC QFP-80 part to be used as half of a pair with their 486SLC cpu that were intended to only be used by various manufacturers as plug-in upgrades for 286 and 386 motherboards, so I would think that the two oddballs were just mis-stamped, but the part identification for the 87SLC QFP-80 was Cx87SLC-25QP, which is quite a bit different from the PLCC-68 parts.

The only thing I can come up with is that the name of the part was changed between the 17th week of 1992 and the 28th week of 1992.

Unfortunately, there is absolutely no information out there about them out on the internet (the 1992-1993 time period seems to be mostly offline, since it was typically paper, and the web hadn't reached the masses yet).

I contacted VIA recently to see if they could tell me anything, but I'm doubtful I'll ever hear anything back from them.

Reply 294 of 298, by kool kitty89

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Cyrix made both SLC and DLC type 387/487 co-pros in the QFP-80 package and they weren't just used on upgrade boards with CPU+FPU pairs, but also sometimes soldered directly to the motherboard or soldered to adapter PCBs for PGA-68 sockets (387 socket) or for passthrough riser adapters for PGA-168 486S or SXL CPUs. (maybe Cyrix 486SXs as well)

Some 486 boards might have allowed external 387 sockets to be used paired with Cyrix 487S or TI SXL etc PGA168 type CPUs, but I'm not sure. (and it was much more common to have the PGA168 socket share the 387 PGA-68 socket and usually make those mutually exclusive installations)

Cyrix's 487S series of FPUs seem to be exclusively QFP-80 packaged and mostly used for adapter sockets, but possibly used soldered to some motherboards. I'm not sure if Cx486S and similar Ti chips worked with the older Fasmath and 87DLC copros or specifically required the 487S.

I don't think AMD or Intel 486SX CPUs support external FPUs. (Intel's 487 upgrade chips aside, which don't really count anyway)

Interestingly, Cyrix also made FPUs compatible with the PGA-121 used for Weitek coprocessors.
The Fasmath EMC series: http://www.x86-guide.net/en/fpu/Cyrix-387.html

I'd guess those used a similar FPU core, but exploiting the memory-mapped Weitek interface rather than the x87 I/O port. Though if there was a similar performance advantage along with Cyrix's double or extended precision support, I'd think those would've caught on more, so maybe there's some other differences. (or the Weitek interface limits things to single-precision)

also, have a Cyrix + IBM timeline:

http://www.cpushack.com/cyrix-486-cpus/

It's not super detailed and there's some gaps in CPU models, but it's neat anyway. (also I don't see a distinction made between the pre-Cyrix IBM Blue Lightning of IBM386/486SLC and DLC lineage vs the all-cyrix designed DX2 that also circumvented IBM's Intel-bound license agreement for only supplying CPUs in complete system boards: ie IBM SLC/DLC chips are soldered to mainboards)

Reply 295 of 298, by kool kitty89

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Judging by some of the experiences recounted in this thread:
TI 486SXL and 486SXL2 PGA168 on socket 3 motherboards

It seems like it's only Cyrix-derived 486S or SXL type CPUs that are likely to work with the 487DLC external coprocessors on interposer boards, and normal 486SX type CPUs from Intel and AMD will not. I'm not sure about UMC's CPUs.

I'm also not sure, but if those 486S/SXL (and SXLC) processors use the same external FPU bus protocol as the 386DX and SX (and DLC/SLC) then I'd assume they'd also accept other 387-compatible FPUs, cyrix or otherwise.

Reply 296 of 298, by derSammler

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kool kitty89 wrote on 2020-06-07, 09:06:

It seems like it's only Cyrix-derived 486S or SXL type CPUs that are likely to work with the 487DLC external coprocessors on interposer boards, and normal 486SX type CPUs from Intel and AMD will not. I'm not sure about UMC's CPUs.

Why would one even think a 487DLC could work with a 486SX? These are incompatible by nature. The 487DLC is a 387DX and just named this way to go with the 486DLC, a drop-in upgrade for a 386DX.

Reply 297 of 298, by kool kitty89

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Not the 87DLC, sorry I'd meant the Cyrix 487S, which I've only seen in QFP-80 form and either mounted directly on a 486 motherboard next to or inside the PGA socket or on a PGA-168 interposer like this:

http://www.x86-guide.net/en/fpu/Cyrix-487S-40 … cpu-no3800.html

I'd thought they might work with other 486 CPUs, but apparently they were intended for Cyrix/TI Socket 1 486S and SXL type CPUs.

I think it's more common to find boards with unpopulated Cyrix 487 pads than actually mounted.

Reply 298 of 298, by Anonymous Coward

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I think the 487S can work with normal 386s. On CPU World I remember seeing one on a PGA68 adapter for use in normal 387 sockets.
Whether or not it has special tweaks for use with a 486S is anyone's guess. I'm inclined to believe that that Cyrix just painted a different logo onto a normal 87DLC just so that it would match with the 486S. Cyrix has a history of badge engineering.

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