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The Cyrix Instead box of happiness

Discussion in 'Retro & Arcade Worklogs' started by badmofo, Sep 5, 2021.

  1. OP
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    badmofo

    badmofo Member

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    Merry Christmas friends - work is finally done for the year so I have a moment to do something fun.

    I've been simultaneously thinking that I'd like to do another hardware project, but also that I don't need any more computers because this Cyrix is the bees knees. The obvious solution of course was to build an exact copy of this machine as a backup :)

    I've been snagging replacement components over the last couple of years as I spot them so I have most of the bits, and to make the whole thing a bit more meaningful I decided it was a good opportunity to improve / learn a couple of skills I think I'll need going forward - replacing capacitors and burning my own EPROMs.

    The overall goal is to replicate the original (Mk1) machine to the point that I can copy its DOS 7 / Windows 98 install to the Mk2 machine, and everything will work and perform exactly the same. No messing around with config files or troubleshooting compatibility issues, etc.

    First step - motherboard. I'm using a Gigabyte GA-586T2, which is nothing special but can handle a Cyrix MII, SDRAM, and has a PS/2 header. The Mk1's motherboard has given me zero issues to date but I assume the weakest link will be the crappy Choyo caps it's sporting, so Mk2 is getting nice new Rubycons.

    I've done a fair bit of recapping in the past with desoldering wick and do not enjoy the process at all, so I decided it was finally time to get a dedicated desolder gun. I looked at a few but cheaped out a bit with a DOSS ZD917 - I liked the idea of having solder / desolder options all in one unit and the reviews weren't too bad. There was some complaints about the gun clogging up after lots of use but I'm really not going to use it much.

    Initial impressions weren't good at all - motherboards of this era were starting to get pretty dang compact so the gun nozzel was generally touching an adjacent trace, which means you can't just jam it on there waiting for stubborn solder to melt. And the solder on this board was shithouse - low lead maybe? Dunno but for several caps I resorted to loosening the legs with the iron until the cap came out, then using the gun to clear the hole. Some holes required the iron on one side and the gun on the other - I tried adding new solder, flux, etc. Anyway I got there - it was easier than using wick and I didn't do any visible damage. In the DOSS' defense I've since tried it on a soundcard and it worked like a charm - 95% of the holes it cleaned right up first try, so it does work well in the right situation.

    IMG_6823.jpg

    Cyrix MII 300 in:

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    Cooler and RAM:

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    New Rubycons:

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    Smoke test and updating the BIOS to the latest version so that the MII is identified correctly:

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    The POST cheekily claims the CPU clock is 300:

    IMG_6980.JPG

    But speedsys isn't fooled, it's 233MHZ:

    IMG_6981.JPG
     
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    badmofo

    badmofo Member

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    My next challenge for Mk2 was finding an equivalent VGA card. Try as I might I haven't come across another ARK2000MT based 'Legend 64' unfortunately so I've tried a few other cards using that chipset instead. Firstly a 'Quadro64' which was a later card with an integrated DAC, and secondly a very handsome looking Hercules Stingray. Both were great - fast and beautiful image quality - but neither could handle the high refresh rates I need for SMS emulation on this machine. I'm putting that down to the DAC - neither card used the Legend's 'GENDAC'.

    But then I came across the ARK based Diamond Stealth 64, which is nearly identical to the Legend 64 both in layout and components. It uses different types of capacitors and a slightly older revision of the ARK2000 chipset, but it uses the same DAC so I grabbed one and tried it out. The image quality is just as nice but it's not quite as bright, and it was a few points slower in benchmarks. There's nothing I can do about the darker image except adjust the monitor, which isn't a big deal. I did find however that swapping in the Legend's BIOS brought the performance into line so that was a win.

    That gave me the excuse I've been looking for to buy an EPROM programmer so I did some reading and went with a 'MiniPro TL866II Plus'. It couldn't have been easier to use really - plugged the Legend's BIOS chip into the programmer's zif socket, copy it to file, pop in a blank chip, select the correct chip type from the list, and write it in. Worked first time much to my delight.

    I'll still be keeping my eyes peeled for another Legend 64 but the Stealth is close enough for now.

    minipro.jpg

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  3. OP
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    badmofo

    badmofo Member

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    Getting the sound card sorted for Mk2 wasn't a big deal because YMF719s cards are still easy to find on the bays; they're getting quite expensive though relatively speaking. I also learnt from a dude over at Vogons - who makes his own YMF719 based sound card - that this chipset uses two clocks at different frequencies, so cards with 2 separate oscillators are best. Not all clones are made equal as we know; some cards only have 1 oscillator, some have none. Those cards will use the possibly inaccurate clock from the ISA BUS so I decided to stick with the Labway version of the card - these have 2 oscillators and seem to be better made in general, with a nice thick PCB.

    I managed to lift a pad while doing the filter mod but otherwise the recapping and modding went fine - the desoldering station I mentioned previously worked like a charm so getting the old caps out took seconds. You can see the filter mod in the pic - SMD caps C11 and C19 have been replaced. Not the neatest job but that's about my best effort :)

    IMG_6993.JPG

    And I finally got my hands on a decent example of the case I wanted for this build. It didn't look great on arrival but I've retrobrited the plastic and cleaned up the metalwork, and it'll come up nicely I think. I'm using a new Startech AT power supply as usual - this one was made ~2016.

    How it arrived:

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    On it's way back to glory:

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  4. atmo

    atmo Member

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  5. OP
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    badmofo

    badmofo Member

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    thanks and yes I did try one of those - it seemed like a nice little card, great image quality and fast. But the integrated DAC couldn’t handle high refresh rates like the 130hz I use on those machine. Generally speaking though a nice option for that era it seems.
     
  6. OP
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    badmofo

    badmofo Member

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    I finally put together the 'Mk2' machine after some motivation issues and real-life interruptions. This project was leaning more towards labour than love there towards the end with dodgy RAM / insufferable pedantry / etc to contend with but I'm happy with the end result at least.

    I tried something different when mounting the cool little 16GB SATA HDD + IDE to SATA converter this time - that's a 5.25 to 3.5 drive bay converter chopped in half, with the disk screwed + double-sided taped on to it. It worked out fine but there must be an easier way :lol:

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    When I grow up I'm going to investigate networking this machine but in the mean time I use one of these NEC based USB 2.0 cards to allow easy transfer of files. Works great in Windows 98 and is super fast.

    P1060866.JPG

    The case went back together fine and looks great I think. Like so many of these generic cases they appeared all over the world so I'm guessing the design was either for sale or - perhaps more likely given it was the wild west - companies just cloned them. Their quality varies from 'OK' to absolute trash but this one falls somewhere in the middle - decent plastic and reasonably sturdy metalwork once it's all screwed together.

    I'd written detailed instructions for setting up the OS, etc on my Mk1 machine so that was all super easy, and as I'd hoped everything runs exactly as it does on the original machine - as it should given the hardware is almost 1:1 but you just never know with these damn old rigs. My only complaints are that the fan on the CPU cooler is a little bit loud so I need to replace that, and I'm not 100% happy with the VGA card so I'll be keeping an eye out for another 'Legend' branded ARK2000MT cards - if anyone has one they want to sell or trade then let me know and we'll work something out :thumbup:

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  7. Vanne

    Vanne Member

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    beaut lil case and internals mate. A few sacrifices to the eternal pc parts hunting grounds should sufice a clear and happy run.

    [​IMG]
     
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  8. Grant

    Grant Member

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    At least grab a couple of NICs and a crossover cable for some IPX multiplayer with its sibling! I don't think they're hard to find but I have a few in my spares pile that I'd dig up for a good cause.
     
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    badmofo

    badmofo Member

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    Lolz good thinking! I do have a NIC in the pile but I just freaking hate networking and always have - even with modern machines I cock it up somehow. Black magic.
     
  10. OP
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    badmofo

    badmofo Member

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    Mixed emotions here at Cyrix Central because the ARK VGA card that's been at the heart of this machine since day one, and which has seen off several attempts to beat it, has finally met it's match - an Nvidia Riva 128.

    I'd seen this card mentioned on VOGONS over the years as being a great DOS option - very compatible and fast - but the few I've seen for sale were always relatively expensive; I finally bit the bullet and am glad I did.

    The ARK can actually provide the same epic SVGA performance as the Riva with a linear frame buffer enabled, but the ARK needs Univbe to enable the LFB and the Riva doesn't. Some games don't like Univbe, including one of my faves, so dropping that from the equation is welcome. Same goes for VESA 3.0 support which is required to increase refresh rates in DOS - the ARK can only do V2 by default so needs Univbe, where the Riva has V3 built in. And the Riva can handle the 130Hz I need for MEKA no problem, same as the ARK.

    The Riva does get hot-ish so I'll be grabbing a heatsink before I try out its 3D functionality - another advantage over the ARK. People don't rave about that side of things but all I'd ask it to do would be Quake, or maybe even Quake II era stuff. This PC isn't about 3D.

    The image quality is great and the geometry / image position is consistent between resolutions which isn't always the case - pretty awesome all told. So I'm sorry ARK old buddy but you're sidelined for now.

    IMG_7171.jpg IMG_7170.jpg
     
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  11. hutts24

    hutts24 Member

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    Are you sure? Now this is from my very foggy memory from back in the 90s at a time when I was in love with my PSX, had forgotten about PC gaming, and a friend gave me a magazine to read (I think it was APC) that had a roundup of the 'graphics accelerators' at the time. I think they were using Quake II for one of the tests and it was up against the voodoo 1 and something permedia and .... well I didn't know what the hell was going on!:lol:

    Anyway, the one quote I remember from that article is "Nothing beats a Riva 128". If I recall correctly it was still superior to all its other newer competitors in the roundup.
     
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    badmofo

    badmofo Member

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    The comments I read were on VOGONS and I suspect that they weren't comparing the Riva to the cards of it's specific era, but rather cards like the Voodoo3 which came out a couple of years later. So yeah the Riva might have rocked on release but the Voodoo2 came out shortly after and was faster and better supported from what I understand - I totally missed all of that stuff at the time too though, I was busy investing all my money in cheap scotch and my car.
     
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