386 Buildlog

Discussion in 'Retro & Arcade' started by Phido, Nov 22, 2017.

  1. OP
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    Phido

    Phido Member

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    I have two 486sxl40's which are the same as the 486sxl-2-50 just rated for a lower speed. However I am confident they will work at 50 or 55Mhz bus and they don't have to be clocked doubled. Hopefully I can do that on regular air cooling. Hopefully that can be my daily driver speed. I'm not expecting a huge lift, but they say the 8kb verse the 1kb cache is worth ~7% in doom. If I can do it on air with cache enabled I will be pretty happy.

    Yep, clock doubling just isn't effective on the 386 bus. It is still interesting to look at. I want to put together a complete set of benchmarks for the CPU's and FPU's I have at a range of clocks and isa speeds.

    However, I have to say, 50Mhz is mind blowing, the machine is really quite snappy. Going back to 40mhz or 33mhz is dramatic in its slowness. At 50Mhz it starts to feel like a 486 something. I also want to do a bench at 63Mhz with the petlier. Just to see. Apparently no one has been there at that speed.

    I don't find the isa bus to be a huge limitation, oc your bus, oc your card. The 386 does struggle to feed it anyway. VL bus was always a pain in the arse to get good. Then your limited on most boards to 25-33mhz clocks, and even then, there are issues.

    At the end of it I just want a pretty snappy 386ish machine to explore the quirks of the platform. The idea was never to build the fastest. It will be happy in DOS and some win95 duties and sits in a modern case with modern peripherals.
     
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  2. OP
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    Phido

    Phido Member

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    Today, no new packages.
    :(

    I am waiting on:
    • More ram (32Mb BABY!)
    • 486sxl (giveme 8kb cache)
    • Faster 12ns cache
    • More powerful pelter
    • more eeproms
    • 110mhz crystal
    • 125mhz crystal
    I tried to flash a bios, didn't work. Only had 256kb chip, maybe wants 512kb?

    I also jammed my finger into a spinning fan, not enjoying that. Lots of blood.
     
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  3. OP
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    Phido

    Phido Member

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    As this build process is winding up.. The benchmarks will cap it off and it will be done, Thinking about the future.

    I really enjoyed building this. I think I want to do it again.

    Will post survey.
     
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  4. Kafoopsy

    Kafoopsy Member

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    Thanks for the blog. it has been very interesting. Specially that parts with the oddball 386 cpus. I have some of those but have never tested them.
     
  5. OP
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    Phido

    Phido Member

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    Thanks for the feed back guys. I do appreciate the likes and the comments.

    Some arrivals from mouser
    12ns cache for high speed bus experiments.
    4)mhz and 50mhz big crystals for slow bus speeds.
    some 512kb eeprom chips for bios flashing..
     
  6. BuuBox

    BuuBox Member

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    Very interesting thread - your next project should be to do similar things to a 486.
     
  7. OP
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    Phido

    Phido Member

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    87.5Mhz crystal has arrived.
    I believe my 486sxl's CPU has arrived but is at the post office.
    I have more ram on the way, I really want to know about 32mb ram.
    I am still missing my 125Mhz crystal. Not particlarly worried about that one as they are quite common in dip 14.

    In the end I will run the benchmarks at:
    20Mhz
    25Mhz
    33Mhz
    40Mhz
    44Mhz
    50Mhz
    55Mhz
    63Mhz

    Provided the CPU can run at that speed (and with the petlier I think most of them will run at least non clock doubled)

    CPU's:
    AMD 386DX (exact same as intel CPU)
    Ti 486DLC (L1 on and off)
    Cx486DRx2 (l1 on and off)
    486SXL (L1 on and off) (clock doubled on and off).

    FPU:
    Cyrix FasMath
    ITT 487
    Intel 387

    Benchmarks:
    Doom
    Wintune 97
    NSSI
    Speedsys
    qaplus
    landmark
    3DSMax 1.1
    Photoshop 3.0.5
    FPU Bench (my bench)
    PMips

    Any requests?
     
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  8. dirkmirk

    dirkmirk Member

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    Pcpbench is a good one to test at 320x200 and 640x480
     
  9. OP
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    Phido

    Phido Member

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    I'll run Pcpbench at both.

    It has arrived. I now have two 486sxl-40's. These are exactly the same as the 486sxl2-50's just rated for a lower clock. However, the one I put in does 50Mhz on air cooling with cache enabled. So very happy about that.
    I can also experiment with clock doubled 25 and 33mhz bus speeds as well (which I assume will be much slower, even with the 8kb of cache).

    I hope to run 50 or 55Mhz as an everyday speed, so really happy with 50Mhz out of the box. I think 60+mhz might be a bit tricky at air cooling, but 55mhz will be plenty fast. For a 386.
     
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  10. OP
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    Phido

    Phido Member

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    More ram arrived...

    32MB *WORKS* despite all the ney sayers. It wasn't easy, but it now all works fine. Photoshop and 3DSMax flies on this.. 386 system...

    125mhz crystals arrived.

    Now it's time to go into the dangerzone.. I think I will need a bigger petlier.. 63Mhz here we come!
     
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  11. OP
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    Phido

    Phido Member

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    110 Mhz crystal has arrived.

    In my memory I have 2x70ns memory, and it isn't happy at 50mhz..

    another 16mb of 60ns fpm parity 9 chip 30 pin memory order from the US. I want that 32mb to work at 55mhz+ dam it!
     
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  12. OP
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    Phido

    Phido Member

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    Stayed up last night learning how to program the C&T PEAK chipset and the Cyrix/TI micoprocessors.
     
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  13. OP
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    Phido

    Phido Member

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    Okay I can turn the motherboard cache off and set the registers for 256kb.. I just need to perfect turning it on.. Trying to convert binary, to hex to decimal at 2 in the morning on a thursday resulted in me nuking my cmos settings.. No biggy, but was a clear sign I should pack it in for the night. So close.. 256kb is the golden grail, because it seems no one has been able to get it to work on this chipset.

    I will change the cache over to 12ns chips now I am pretty confident of getting 256kb working. Hopefully it is stable.. Should push the benchies up just a smidgen. at 50 or 55mhz the motherboard cache is operating pretty quick with low latency, and the main memory is pretty quick as well. So it just really becomes the ISA bus holding things up.

    I've also worked out how to get 486dlc/drx2/sxl's working with speedsys (flush on hold mother f's! but turn your flush pin off)..

    I also need to adapt my 110 and 125mhz crystals to dip-14 from dip-4.. Maybe this weekend.

    I really want to see if 55mhz is stable as a every day setting, I don't think 62mhz will be because clocked doubled 33 isn't even with sub zero cooling.

    The end of the day it will look like this:
    Ti 486sxl, 8kb cache L1, running at @ 55Mhz
    Cyrix Fasmath387 coprocessor (@55Mhz, also with the bus at 55mhz latency is less of a problem)
    32Mb, parity, 60ns ram at 55Mhz. Interleaved. (this is fast, will beat most 486 motherboards, ~45mb second)
    256Kb, 12ns L2 cache at 55Mhz (again, faster than most 486 cache)
    32Gb SD card, SD2IDE converter Fat32 partition. (very fast)
    11Mhz ISA bus with zero waits (pretty fast, hopefully everything can work at 11 otherwise its 8mhz at)
    2Mb Cirrus Logic 5429 SVGA card, clocked at 80Mhz ram (up from 50). This is quite fast, probably equal fastest ISA card. It clocks higher than the 5434.
    1:1 DMA mode (@ 55mhz!)
    3Com Network 10mbps (isa)
    AWE32 (decent)
    48x cd drive (fine for a 386/486)
    5.25 1.2mb drive
    3.5 1.44 drive
    gotek emulator

    Basically with everything flat out I am hoping for it to be as fast as a 486DX33/486DX40 with an average VL bus card. While that seems silly, it has been fun making a red hot 386. It is also over twice as fast (in clock) as the 386 back in the day, and if I disable the l1 and l2 cache (mine never had any mobo cache) and flick in a 50mhz crystal, I can experience exactly what it was like with my original 386Dx/25.

    Chocka block slow.

    But flick them on and you have a mid range 486 setup which is quite usable in early win95 and most DOS stuff (pre 1996 (when Pentiums reign)). Windows is snappy, Photoshop and other programs a very usable. It's great for coding DOS stuff because you have a real (extra featured) dos environment, early win95 enviroment. Slow enough it doesn't feel like overkill when your using it, it feels authentic. But fast enough that it feels snappy.
     
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  14. OP
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    Phido

    Phido Member

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    Ok, having problems with my 55mhz crystals. They aren't vibing with me and I may have inadvertently destroyed them.
    While annoying, I don't seem to have done any other damage. Also I think I will order some 115mhz crystals. A little faster and more conventional (I don't have to build an adapter for them).

    62.5Mhz does work. But it is very patchy. I can make light benchmarks work with L1 disabled. But doom crashes. With l1 enabled, it's very flakey, most things won't start, even with the cpu near zero degrees.

    So i have 50Mhz, and 63mhz.. Just need something between them. 57Mhz doesn't look like a bad place to aim. And they come in DIP-14 cans..

    Hopefully I can get airstable.
     
  15. OP
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    Phido

    Phido Member

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    115mhz crystals ordered.

    If this doesn't work I will stop at 50Mhz..
     
  16. dacow

    dacow Member

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    Holy bejeezus! You sir are a man no a mission :D :D
     
  17. OP
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    Phido

    Phido Member

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    The 386 has a special place in my personal history. The details of which are actually inconsequential. It isn't a vanity project. Which is why when I went on vogons I deliberately came across as an newbie pumpkin.

    If I wanted the fasted I would have just paid someone a silly amount of money for a blue lightening 100mhz 386sx. Journey over. Or if I just wanted a level of performance a 486DX266 would be faster and much cheaper and easier. The build would have finished on page 1.

    I wanted a 386 journey to be difficult and with many turns. Fitting an AT mobo in a matx case that doesn't fit it. Choosing a chip-set that had potential, but no one had been able to get working properly (cache and memory). Choosing the unloved over the most desirable. Choosing the road less travelled with more pitfalls and tribulations.

    But if you looking for something that conveys meaning and emotion of this project for me.. and why I can't stop.



    This project is winding down, but it isn't stopping. I will probably always update this thread with my attempts to get the 256kb cache working. Mobo l1 cache modifications. There will always be something to continue and improve.
     
    Last edited: Aug 6, 2018
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  18. OP
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    Phido

    Phido Member

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    Another 16mb of brand new 30 pin 60ns 9 chip parity ram..

    And I now have 32mb at 50Mhz..
     
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