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Reply 60 of 325, by elianda

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Well probably a tiny bit, but far from playable. There is some info on the performance difference when upgrading to a matched pair of Cyrix DLC (CPU+FPU) in the cyrix guide.
I have a copy here on my ftp: ftp://78.46.141.148/docs/cyrix/cyrix.txt
I ran the Quake also with an ULSI FPU which should be one of the fastest standard 387 FPUs and it increased the fps score by 0.1.

From own experience using Cyrix DLCs reduces the compatibility, there will be issues.

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Reply 61 of 325, by Anonymous Coward

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EISA didn't really have a good selection of graphics adapters. Most of them were ET4000AX or S3 928. EISA 386 systems are rare. Even rarer than VLB 386 systems. I have only ever owned a single 386 with VLB slots, and the VLB performance was quite gimped.

I don't know of any substantial difference between older Fasmath FPUs and 487DLC other than rebranding and a few compatibility updates. Supposedly the later releases are actually *slower* than the earlier ones.

"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 62 of 325, by elianda

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Anonymous Coward wrote:

I don't know of any substantial difference between older Fasmath FPUs and 487DLC other than rebranding and a few compatibility updates. Supposedly the later releases are actually *slower* than the earlier ones.

Well, the Cyrix guide says different, but if someone has such a system running he may deliver some bench results?

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Reply 63 of 325, by Ailicec

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I've also run Quake on a 386/387.. Fun experiment, I got about 1 FPS on the gimped motherboard I was talking about above. I remember playing games back then that ran as slow or worse, with MUCH less sophisticated graphics (Moraff's World, for example). A different style of game could have been very successful with that level of performance.

Also, I got windows 95 installed with the openGL screensavers. with math coprocessor, they ran at a frame or two. Without the copro, I don't think they ever managed to finish a frame, or if they did it was painful beyond belief. Actually, its pretty cool you can run software openGL on a 386 and get much of anything to happen.

One of the 387 clones, IIT I believe, included a special instruction for matrix multiplies, which is essential for 3D. Supposedly it reaches a 486 like level of performance. Speculating on my part, this is because after you load it up with the matrix, it can do a lot of operations w/o communicating with the CPU. The 386-387 communication overhead is pretty awful, taking as much time to transfer operands as it takes to do some of the simpler operations.

Anyway, special extra credit to anybody who can rig up an IIT optimized Quake and report how it runs 😀 It should certainly help the transforms, not sure if it would speed up the whole game that much. An academic exercise but a fun one!

Reply 64 of 325, by feipoa

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Mithloraite wrote:

That is a very interesting website you found. The following is quoted from that website, which I was not previously aware of:

Aparently there is a known problem whereby an early Cx486DLC's will crash a system with the one of the Cyrix FasMath Cx387+, Cx83D87, or EMC87 math coprocessors. This is tied to sychronization problems with FSAVE & FSTOR instructions. Later DLC's that have this problem fixed will have the letters AB printed in the lower right hand corner.

Plan your life wisely, you'll be dead before you know it.

Reply 65 of 325, by Anonymous Coward

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I believe this is the website where I originally found the DRx utility.

"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 66 of 325, by elianda

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Ailicec wrote:

One of the 387 clones, IIT I believe, included a special instruction for matrix multiplies, which is essential for 3D. Supposedly it reaches a 486 like level of performance. Speculating on my part, this is because after you load it up with the matrix, it can do a lot of operations w/o communicating with the CPU. The 386-387 communication overhead is pretty awful, taking as much time to transfer operands as it takes to do some of the simpler operations.

Anyway, special extra credit to anybody who can rig up an IIT optimized Quake and report how it runs 😀 It should certainly help the transforms, not sure if it would speed up the whole game that much. An academic exercise but a fun one!

Yes the FPU demodisk that came with the IIT 3C87 advertises the 4x4 matrix operation as the IIT FPU killer feature. I haven't found software that uses it though...
I doubt there is already an IIT optimized Quake out there and even while the source is available the effort would be tremendeous to review and patch all the FPU code just for IIT. Still it wouldn't reach playable framerates afterwards.

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Reply 67 of 325, by huubwen

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Motherboard: PC Chips M-321 rev 2.6
Chipset: PC Chips
Cache: 128k 20ns
Memory: 32M Parity
CPU: AM386DX/DXL-40
FPU: Cyris FasMath CX-83D87-40-GP

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Reply 68 of 325, by feipoa

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huubwen, can you let me know what chipset that PCChips board uses? You'll probably need to use some software utility to find out as PC Chips re-branded the chipset with its own markings.

Also, is your memory speed set to the fastest speed? Your memory throughput seems really slow.

Plan your life wisely, you'll be dead before you know it.

Reply 70 of 325, by Mithloraite

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elianda wrote:

Well probably a tiny bit, but far from playable. There is some info on the performance difference when upgrading to a matched pair of Cyrix DLC (CPU+FPU) in the cyrix guide.
I have a copy here on my ftp: ftp://78.46.141.148/docs/cyrix/cyrix.txt
I ran the Quake also with an ULSI FPU which should be one of the fastest standard 387 FPUs and it increased the fps score by 0.1.

on a second thought, might a ~clock-doubled FPU~ improve Quake I wonder?

Wasn't it the killer feature of Quake, to kill non-Intel competition. Sure it's an academic interest but if that's the bottleneck, and we clock-double it...

There was a 25x2 50Mhz(?) FPU made by IIT.

Reply 71 of 325, by Anonymous Coward

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Probably not. Not only was there a 2x25MHz FPU from IIT, there was also a 2x33MHz FPU from ULSI. I own both of them. I haven't tested the IIT because the 25MHz bus pretty much kills the memory performance. But I have tested the ULSI. It's only a little 2x33 is only slightly better than running at 1x40. I think it clocked as equal to a 45MHz 387.

Oh, and forgot about overclocking to 80MHz. I only have one of these chips, and they are VERY rare. Infact, they were never for sale to the general public. I was lucky enough to get my hands on one that leaked out.

"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 72 of 325, by Mithloraite

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> haven't tested the IIT because the 25MHz bus pretty much kills the memory performance

Good point... Thanks! memory @25Mhz bus should be the performance death indeed.
I've located one SXL2 8KB cache cpu by TI and 2x25 IIT pair for some $70 and was contemplating... On the ~greatness~ of the results. Perhaps not in this case. 😀
ULSI 2x33 looks MUCH better. But it's true I've never seen it sold.

indeed I thought also about overclocking. Oscillators or jumpers can do the trick...
If at all possible, it would be great to see the Quake demo results with this ULSI, overclocked or not.

Perfection is the key. Fatality is the key. (c)

Reply 73 of 325, by Anonymous Coward

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Maybe the SXL2 and IIT X2 FPU wouldn't be speed demons, but it would certainly make for a very cool 386. How many people can boast about both clock doubled FPU AND CPU? Personally, I find $70 a little high, but that's the price you pay for not being patient.

"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 74 of 325, by feipoa

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Anonymous Coward wrote:

2x33 is only slightly better than running at 1x40. I think it clocked as equal to a 45MHz 387.

That would make for an awesome 386 setup, but only if it is run on a non-386/486 hybrid board. I always found the dual socket 386/486 board rather unexciting. Mine was awkward and I tossed it a long long time ago.

Anonymous Coward wrote:

Oh, and forgot about overclocking to 80MHz. I only have one of these chips, and they are VERY rare. Infact, they were never for sale to the general public.

I don't think 2x40 is so far fetched. Were the 33/66 chips spec'd to run without a heatsink? With a heatsink and fan, 80 MHz doesn't seem so far off.

Plan your life wisely, you'll be dead before you know it.

Reply 75 of 325, by Anonymous Coward

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You have to remember that none of these chips were made by intel, and were probably using outdated production facilities. If the 33/66 is anything like the Cyrix DRx2, there's no way it's going to get to 66MHz.
I can't recall if it requires a heatsink or not, but I will run it at stock speed for a while and see how hot it gets. If I can heatsink and fan it without using epoxy, I'd be willing to try running at 80. The question is how on earth I can anchor a heatsink without using glue.

"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 76 of 325, by feipoa

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Fab your own bracket which clamp to the bottom of the CPU, kinda like with those cheap 486 coolers, except use steel in your design.

Alternately, you can probably even use some scrap metal which is already in a mini c-clamp form. Drill a set screw through each c-clamp to tighten the clamp down onto the heatsink. The heatsink would need to have a little hole in to access the set screw. There are also two grooves cut into the heatsink to inset the c-clamp on two sides. The gap between the CPU and PGA is about 1 - 1.5 mm to allow the C-clamp to grab. This is difficult to decribe in words, but I'm sure you can come up with something similar. Better yet, hire a free co-op to whip up some SolidWorks drawing and send it for prototyping! Apparently, co-ops work for free these days.

Plan your life wisely, you'll be dead before you know it.

Reply 77 of 325, by carlostex

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Has anyone tried to replace a 80MHZ Oscillator for a 100MHZ one to overclock an AMD 386 DX 40 to 50 MHZ? Would this also be more suitable with a ceramic package CPU?