Re: A brief comparison of 386 FPUs

Posted on 2022-06-02, 03:38

by

by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

On the 4x4 instruction.. you load the 4x4 transformation matrix into alternate register sets, then leave them resident while you load the fairly small 4x1 vector. Typically the transformation matrix is reused many times, so this saves a huge amount of communication overhead. For the time, a very big …

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Re: Help identify 386 motherboard

Posted on 2015-07-08, 02:15

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Good find in that PDF. So, its an ECS. If you are lucky it will boot without any cache. Its amazing how many boards that were made 25 or 30 years ago when the market was much smaller.

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Re: Help identify 386 motherboard

Posted on 2015-07-05, 21:44

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What is printed on the BIOS chips (the two left of the SIMMS, one with a sticker on it with some writing)? I see an oscillator at the bottom-left of the board - the shiny tin can. What number is printed on that? There's a good chance that it is twice the CPU's speed (ie if it says 66 mhz, then it …

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Re: Weitek 4167 - Software?

Posted on 2015-07-05, 21:35

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

To try to answer the original question - more info on compiler support, from the 1988 3167 datasheet. The WTL 3167 coprocessor is supported by the UNIX operating system (System V release 3.0). Operating system support includes coprocessor addressing, pres-ence detection at power-up, context-switch …

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386 Turbo Utility

Posted on 2015-07-04, 21:45

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have a 386 Baby Screamer Series 42 motherboard that seems to have the turbo stuck off. The usual keyboard controls (Control alt +/-, etc), the turbo jumper, and the BIOS options don't do anything to change it. Short story, I was wondering if anybody has a software utility to set the turbo state on …

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Re: Weitek 4167 - Software?

Posted on 2015-07-04, 03:28

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

My late-era (~1992) 386 has a 121 pin "EMC" (extended math coprocessor) socket. You can put a 3167 or 387 in, but not both. By that time I'm not sure who was buying a lower-end 386 and sticking a very expensive weitek in it.. but you could if you wanted to. I've read that some motherboards had both …

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Re: Weitek 4167 - Software?

Posted on 2015-07-04, 01:40

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by Ailicec

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think Watcom C does, or did support the Weitek. I wish GCC supported it so I could recompile some projects, but I can't find that it ever did. In the 386 days, the Weitek should have blown away any 387. The interface overhead made any 387 operation at least 20 clocks, where weitek may have been as …

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Re: 386 / 387 Concurrency

Posted on 2014-08-19, 09:35

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by Ailicec

in PC Emulation

in PC Emulation

The Pentium is much better documented on the overlap, latency and throughput. The FXCH trick is basically that you can start an op like FMUL, swap it out of the way using FXCH during the same cycle, and start a new FMUL the next cycle. It gets around the x87's need to use the top of the stack, which …

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Re: 386 / 387 Concurrency

Posted on 2014-08-17, 02:18

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by Ailicec

in PC Emulation

in PC Emulation

The coordination is automatic (unlike the 8087, which needed those FWAITs or bad things would happen). But its up to the programmer to not give two float ops in a row. I reran my tests from last year. CPU is an AMD-40 (running at 33 mhz). These tests look like this (forgive my rather poor assembly …

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Re: 386 / 387 Concurrency

Posted on 2014-08-15, 08:04

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by Ailicec

in PC Emulation

in PC Emulation

The asynchronous terminology usually refers to the fact that the Intel 387s could be run at a different speed than the 386. They can run within 10/16 to 16/10 the 386 clock speed. This feature was hardly used at all. The clones probably simplified their design a lot by skipping it. I've seen similar …

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386 / 387 Concurrency

Posted on 2014-08-15, 04:13

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by Ailicec

in PC Emulation

in PC Emulation

I'm interested in this from an optimization point of view, but thought the emulation crowd would also find it useful for cycle accurate emulation, and might know about it already. It may also apply to some extent to the 286 and 486. When the 386 encounters a coprocessor instruction, it hands it to …

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Re: Post your 386 Speedsys results here

Posted on 2013-01-20, 05:26

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

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 …

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Re: Post your 386 Speedsys results here

Posted on 2012-11-25, 20:25

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

Yes, I've never got any of the keyboard controls to work. There's supposed to be ones to control turbo, cache, and get in the BIOS, none of them work. Maybe because I had to replace the keyboard BIOS chip? Sad if that killed my performance.. I do have an EEPROM burner, if I ever got the data I could …

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Re: Post your 386 Speedsys results here

Posted on 2012-11-25, 07:00

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

For fun, I'm posting this from the 386, painful as it may be. No more luck, I tried different combos of SIMMs and some jumpers, but could only make it slower. Checked the BS16 pin to make sure it was running as 32 bit, and it was.

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Re: Post your 386 Speedsys results here

Posted on 2012-11-15, 09:21

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

The other benchmarks all indicated 33 MHz. The motherboard manual says non-turbo is 8 MHz. The odd turbo light behavior still bugs me, though. Seems like the cache implementation is crummy or not working right.. it seems to be 33 MHz, but with very little memory bandwidth.

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Re: Post your 386 Speedsys results here

Posted on 2012-11-10, 05:14

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

You may be right. The machine starts with the turbo light on, but never boots; after a reset, the light goes off and it boots. Maybe it can't run stably at full speed. However all the CPU speed programs say its running at 33 MHz, so I'm not sure thats it. I may have to get an O-scope one of these …

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Re: Post your 386 Speedsys results here

Posted on 2012-11-10, 01:14

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by Ailicec

in Marvin \ System Specs

in Marvin \ System Specs

Sorry I'm a bit late to this party.. This is a 386 Baby Screamer Series 42 motherboard and 386DX/33. 32 megs of of 70ns 40 meg SIMMs. Its running off a compact flash card, leading to odd hard drive numbers. The memory bandwidth, esp cached, and CPU numbers seem really low, and I'm not sure why. I …

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Re: ATI 3D Rage Pro wrapper?

Posted on 2012-07-29, 02:21

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by Ailicec

in PC Emulation

in PC Emulation

I took a look at the links.. unfortunately, this chipset seems to be at the dawn of the era where the makers got very stingy with releasing information, and I don't see the actual SDK floating around, even though it is referenced. I think you'd need to find that to get anywhere. You can always try …

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Re: Seeking Space Orb 360 drivers/software

Posted on 2012-03-15, 05:09

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by Ailicec

in PC Emulation

in PC Emulation

I'd avoid the driver detectives like the plague. If they do nothing, you'd be lucky; more likely they malware. At best, they've just scraped up most of the same drivers you can find yourself. Same with BIOS update services. Nobody is developing 3rd party BIOSes and very very few are doing third …

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Re: Options for 3rd party boards, expansion cards for XT/AT class systems

Posted on 2012-02-05, 02:50

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by Ailicec

in PC Emulation

in PC Emulation

Along these lines, does anybody know how the BIOS discovers the RAM on an expansion board? I've looked all over and not found much. Its almost like people aren't building ISA memory cards anymore! My guesses are: 1) An option ROM is picked up by the BIOS (the BIOS scans for these) and the ROM …

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