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Micro ATX 486 - what's the degree of interest?

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Reply 80 of 116, by matze79

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Tiido wrote on 2020-03-05, 19:32:

FPGA based motherboards are in my todo list, hard part is the BIOS that I have actually slowly began working on.

Just use SeaBIOS or other OpenSource Variant ?

AO486 made a lot of progress:
https://github.com/MiSTer-devel/ao486_MiSTer

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https://www.retroianer.de - under constructing since ever

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Reply 81 of 116, by Nitroraptor53

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It's a long shot, but I'm gonna try to win the lottery, all goes well we'll be getting an MATX 486 soon.
Edit: also my 100th post!

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Reply 82 of 116, by Cyberdyne

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Better just make some mATX or ITX motherboard with a x86 SsystemOnChip and some ISA and PCI slots. Thats abot it, why that 486 craze.

I am aroused about any X86 motherboard that has full functional ISA slot. I think i have problem. Not really into that original (Turbo) XT,286,386 and CGA/EGA stuff. So just a DOS nut.

Reply 83 of 116, by computerguy08

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It's an interesting topic you developed here, so I'll give my own thoughts on it.

Usually, I don't like spending very much on a motherboard, therefore I'm always trying to find the best bang of the buck.
Paying over $200 on a new 486 board is not in my books and if I were you, I would make the following changes:

  • still microATX, but only PCI and ISA slots (EISA is really unnecessary and expensive to implement IMHO, might as well go for a real 486 or Pentium board at that point)
  • onboard network card instead of onboard VGA (I think the RTL8139 is very compatible and readily available)
  • use as many off-the-shelf parts as possible to keep FPGA costs down (but keep FPGA chipset)
  • keep the physical Socket 3

This should still give you an unique and brand new 486 microATX board to combat the ever increasing scarcity of old 486 boards.

If any of these issues has been addressed before, I'm sorry for repeating them here.

Looking for a motherboard? You can find it in Ultimate Hardware 2019: http://www.win3x.org/uh19/motherboard/search
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Reply 84 of 116, by The Serpent Rider

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Best option, from my point of view, would be 3 PCI slots + 2 ISA slots. I also think that onboard VGA isn't best option.

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Reply 85 of 116, by LightStruk

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Nitroraptor53, the goal is to use new parts, right?

Similar to what dionb pointed out back in March, there are two separate lots of new Elan SC520 CPUs right now on eBay - one of 100 pcs for $1000 ($10/cpu), and another 67 pcs for $599 ($8.94/cpu). In my experience, eBay sellers of new-old stock like this will frequently let you haggle the price down. As for finding the cash to buy in bulk, if you make a proof-of-concept board, getting the funds to buy these lots (or others like them) from Kickstarter would be trivial.

Benefits of the SC520:

  • It's an AMD 5x86 at 133 MHz. Best of the 486 era outside of nearly impossible to find high-clock IBM or Cyrix parts.
  • There's no need for any FPGA!
  • You wouldn't need to find a supply of Socket 3s.
  • Supports up to 256 MB of standard 66 MHz SDRAM. Having such high-speed RAM reduces the impact of not having any L2 cache by default.
  • You don't need to integrate any other major components on the board if you want to keep the price down. If MicroATX is the goal, put SDRAM sockets, three PCI slots, and an ISA slot on the board, and let the user supply their own SDRAM, PCI video, PCI ethernet, and ISA sound cards, all of which are plentiful. If you want to include Ethernet on-board, then PCI ethernet controllers are the easiest chips to find of those three.
  • The SC520 also has two COM ports integrated.
  • Core 2.5V, logic 3.3V, and 5V tolerant!

Downsides:

  • Super I/O is not built-in, so no integrated floppy, LPT, or PS/2 ports. Not sure which Super I/O chip the NuXT uses, but it solved this problem and that's a much less integrated starting point. Although a parallel port is pretty pointless nowadays, it's hard to imagine a 486-era computer without a floppy drive, and there's no getting around the need for some kind of keyboard controller.
  • Similarly, the IDE controller is not built-in. Also solved by the NuXT, but you don't really need to solve this problem if you don't want to. PCI SATA and PCI IDE cards are less than $10 new.

Reply 87 of 116, by wiretap

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For general core design, here is a decent starting point for integrating use of an original processor with I/O: https://www.retrobrewcomputers.org/doku.php?i … linux-sbc:start

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Reply 88 of 116, by johnnycontrario

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Here's my opinion, for what it's worth.

Making new 486 motherboards is a really cool idea, but there is little practical or economical reason to do so. Maybe someday when working original 486 boards are rare and very expensive. That said, I love the idea, and I would definitely enjoy building one as a kit.

I believe that video performance will be a major sticking point for most people. Implementing the VLB or PCI bus does not seem trivial compared to slapping everything onto an ISA bus. If you provide no VLB or PCI slots, then your video FPGA reproductions would have to be either perfect or have the ability to flash bug fixes.

I think modernizing I/O is actually a tricky subject. What should the shelf life be on one of these motherboards? Compact Flash is a good illustration. CF cards are basically obsolete these days and will eventually go away completely. A motherboard modernized with an obsolete CF slot is pretty ironic, and will be pretty annoying when CF cards become impractical. You could opt for SD cards instead, but you'll eventually run into the same problem. In my opinion, the best way to keep an old motherboard from becoming obsolete, is to make sure it has period correct I/O and put all the modern connections on the adapters.
This gives me an idea: rather than embedding non-486 era I/O onto the motherboard, create an EISA or PCI super I/O card with contemporary connections (USB KB & Mouse, USB/SATA/SD to IDE, etc.). This I/O card could be replaced with a newer one if the interfaces become obsolete.

You may want to research industrial computers. The 486 platform is very common in older industrial applications, and because those machines have service lives in the decades, newer 486 chipsets and boards are actually fairly common. I think the major problem with many of these newer 486 implementations is form factor. Many don't fit in a standard case or they have a PC104 header instead of ISA slots, etc. Others have some compromises in the integrated graphics or chipsets making them unwieldy for playing games, and some of them don't implement DMA on the ISA bus... My point is that the technology is there, it's just being made for industrial applications rather than for PC gaming. You may not need to mess with FPGAs: many of the chips that went into these industrial computers are recently-obsolete rather than obsolete-since-the-90's. For example, you could get a supply of the ZFx86 chips that Jakethompson mentioned,and build a modern form factor motherboard with a PCI slot and a couple ISA slots. This strays from the original idea of using existing discrete CPUs, but something like the ZFx86 chip (System-on-a-Chip) would eliminate the need to design your own chipset from scratch.

Coincidentally, I found this product (probably unobtanium), that's almost exactly what I just described: https://www.esapcsolutions.com/product/esa-in … hared-pci-slot/

Reply 89 of 116, by LightStruk

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ZFx86 is a dead end. The CEO of ZF Micro announced the end back in 2012 after legal troubles.

I recommended the AMD Elan SC520 because historically it's a widely used SoC and there are still "new" (unused) chips available. With its PCI and ISA busses, any PCI or ISA video or sound card would be supportable.

As far as I can tell, the only CPU supplier still making new retro x86 CPUs worth considering is Vortex86. These derive from the Rise mP6 lineage. There are several variants of the chip, stretching from low 486 to high Pentium 2 level of performance (but no i686 insturctions), with a variety of different busses and integrated components included. I have a computer with one of those inside (specifically, an EBOX-3350MX "VESA PC" with a 933 MHz Vortex86 MX) and the DOS gaming performance was seriously underwhelming. It could easily have been the embedded video was not optimized for classic VGA modes, who knows. The only way to know for sure would be to get one without integrated video and pair it with a known good high-quality PCI video card.

I suspect it's still possible, although challenging, to source new-old-stock AMD Geode LX chips. These derive from the Cyrix 6x86 and Cyrix Media GX lineage. They are decent performers (I have a 500 MHz model myself) and are pretty nice for Windows 98 SE 2D gaming (using WDM Windows XP drivers), but don't have SoundBlaster compatible sound. That could be added via an LPC bus to ISA bus adapter. The result would be a late Pentium MMX or early Pentium 2 equivalent computer, not a 486.

Last edited by LightStruk on 2020-08-30, 01:49. Edited 3 times in total.

Reply 90 of 116, by johnnycontrario

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I didn't know about ZFx86 chips being a dead end. For some reason I thought they were the same thing as the Vortex86 chips. Oops.

That EBOX is an interesting machine. Every time I look at a machine like this, I always wish it had an ISA slot for a sound card.

I think just about everyone will have differing expectations on performance and even skewed expectations of what each x86 platform should be capable of. Just about the only way to avoid disappointing everyone would be to create a universal socket-3 motherboard with no integrated devices and plenty of slots. I'm probably repeating myself here: creating a chipset from scratch to add PCI and/or VESA and to handle the wide variety of 486 chip configurations is *ambitious*. Maybe there are new or new-old-stock chipsets still available. This could make the project more realistic. The FPGA development could then be put towards creating I/O cards to connect to modern peripherals. Being able to eliminate the dongles and adapters I'm using for retro computing would be a welcome innovation.

Reply 91 of 116, by keenmaster486

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In my professional Guy On The Internet opinion, here is what is needed:

  • Single board computer a la Raspberry Pi
  • x86, with enough oomph to run a lot of different things but not so much it gets too expensive. Ideally late Pentium III / Pentium M type of speed.
  • Real ISA bus
  • SB16-compatible sound
  • Some wavetable MIDI device
  • Very compatible VESA/VGA 2D video and Voodoo-compatible 3D accelerator, but unlocked. No need to restrict speed on this right?
  • Some very compatible ISA Ethernet adapter
  • (would require much new work) ISA WiFi that presents itself as an Ethernet card and is configurable by telnet or HTTP
  • IDE controller
  • Breakout board with extra ISA and PCI slots
  • USB ports
  • Serial, parallel, VGA, joystick ports

Then this board could be used by itself, placed in a case, OR, in my very important corollary to this, used in an open source laptop project that would put the whole thing in a relatively compact package with floppy/CD, CF/SD to IDE, a great keyboard, TFT LCD, and a huge battery.

I flermmed the plootash just like you asked.

Reply 92 of 116, by Socket3

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Nitroraptor53 wrote on 2020-03-05, 13:55:
jheronimus wrote on 2020-03-05, 11:03:

Honestly, simply a 486 motherboard with ATX connector and support for all CPUs would be awesome. I think a whole new VGA chipset with Glide compatibility would be an overkill. IMHO, people put Voodoos in 486 systems mostly for shits and giggles — there is no need for such a combination.

Agreed, though I've never seen a POD with Voodoo.

I have and it runs great. The 3dfx versions of Quake, Descent, Tomb Raider and Carmageddon run considerably better then their software render counterparts (although Carmageddon is still not really playable). I agree sticking a voodoo in a 486 is a bit eccentric, but it does make a sizable difference in performance: So... I picked up a simple unassuming beige AT computer and it turned out to be this....

You don't really need a POD83 either. A 133MHz 586 also benefits greatly from a voodoo2 card in supported games.

ON TOPIC:

For me to be interested, the board would need to have:

- A CPU socket. I'm not interested in modern implementations of the 486 core, I want to be able to use my 486 CPUs in it. I wouldn't mind an on board CPU, but only if it can be disabled so I can use one of my 486 chips in it, and if said on board cpu does not raise the price of the motherboard significantly.
- on board L2 cache or at least L2 cache sockets.
- 2 PCI slots
- ISA slots
- 3.3V CPU support.
- ATX or AT form factor (with ATX power connector like AT super socket 7 boards). mATX form factor only has 4 expansion slots, with is too few for a 486
- cost under 200$
- 1 VLB slot would also be appreciated.

Don't much care for USB (PCI USB cards are cheap and easy to find), on board video with glide support, EISA and other nonsense.

As for modern convenience, EDO simm or SDRAM support would go a long way, since FPM simms are rather rare in some parts of the world. The ability to use EDO would be a great help. If someone could make a board like this, I'd be interested.

Last edited by Socket3 on 2020-08-29, 21:49. Edited 1 time in total.

Reply 93 of 116, by LightStruk

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There's no way a new motherboard could have any 3dfx parts on it, or an FPGA recreation for that matter. There are obviously no new-old-stock chips, and used cards are as expensive as this motherboard should be. Reimplementing a Voodoo Graphics or Voodoo 2 on an FPGA is orders of magnitude more complicated than implementing an SVGA chip or northbridge or even a CPU. Reimplementing it correctly is even harder - it would be more accurate to use a Glide wrapper with another 3d chipset.

Look, I get it. I had a Voodoo 2 8 MB back then, with my Pentium 200 MMX. It was awesome. But nostalgia for that card does not make it reasonable or possible to include 3dfx support on a new 486-class motherboard. It's also not reasonable to pair a 3dfx card with a Pentium 3 or later - Nvidia and ATI parts were better by then, and there were no Glide-only titles by that point. It's a narrow window in PC gaming history that benefits from a true 3dfx card.

Reply 95 of 116, by canthearu

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Yeah, damn dopey idea to put a 3dfx on a 486. The 486 isn't fast enough to run the sort of games that want a 3dfx card, so you would be basically doing it for the lulz.

Fine, I get it, you want to play around with a 486 with a Voodoo card in it .... well then fine. Get yourself a voodoo 1 or 2, a 486 PCI computer, and put the voodoo card into the 486. Then run 1 or 2 of the games that might work in such a strange configuration, play around with it a bit, then realize that you have nothing else do with with such a configuration, and get it out of your head. Baking a 3dfx chipset onto a 486 motherboard permanently is a waste of everyone's time.

Just because you CAN do it, doesn't mean it is a good idea.

If you are baking video in, then a 486 needs video capabilities of:
a) Fast 2D acceleration, with a decent selection of BitBLT ops, colour expansion and maybe 2d polygon draw/fill, that fits well with Windows 3.1 and 95 GDI acceleration.
b) Good 32bit high speed connection between the CPU and video memory, and high register manipulation speed for bitblasting games into video memory.
c) High memory size to let you use higher video modes if Windows.
d) A good, stable RAMDAC that can co-exist well with LCD monitors, without vertical bars and such. A DVI output would be even better, as well as VGA.

Reply 96 of 116, by LightStruk

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canthearu wrote on 2020-08-30, 03:46:
If you are baking video in, then a 486 needs video capabilities of: a) Fast 2D acceleration, with a decent selection of BitBLT o […]
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If you are baking video in, then a 486 needs video capabilities of:
a) Fast 2D acceleration, with a decent selection of BitBLT ops, colour expansion and maybe 2d polygon draw/fill, that fits well with Windows 3.1 and 95 GDI acceleration.
b) Good 32bit high speed connection between the CPU and video memory, and high register manipulation speed for bitblasting games into video memory.
c) High memory size to let you use higher video modes if Windows.
d) A good, stable RAMDAC that can co-exist well with LCD monitors, without vertical bars and such. A DVI output would be even better, as well as VGA.

If we're still talking about integrating the video onto the board, instead of requiring users to supply their own PCI or ISA video card, then sure, it would be terrific to find a video chip that does all of those things. I would argue that the video chip's VGA / VESA performance in DOS is way more important than its 2D/GDI acceleration - few people would want to run vintage AutoCAD or QuarkXpress on this thing.
As for DVI / HDMI, the DVI spec was only finalized in 1999, so that's the earliest you will find any chip with support for it.
I wonder if anyone could get their hands on a supply of STPC Atlas SoCs. Those had integrated video, a 5x86 class processor, PCI, ISA, USB, and support for CRTs and TFTs - which would probably not have been too difficult to wire up to a DVI or HDMI transmitter.

Reply 97 of 116, by Warlord

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I don't think it should have onboard graphics. RIVA TNT would be a good choice though. As it has all of those features.

Anyways I wouldn't do a MARX 486. A PCISA 4 slot backplane that would mount on in a MATX with a SBC might be easyer.

Reply 98 of 116, by canthearu

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LightStruk wrote on 2020-08-31, 01:38:

If we're still talking about integrating the video onto the board, instead of requiring users to supply their own PCI or ISA video card, then sure, it would be terrific to find a video chip that does all of those things. I would argue that the video chip's VGA / VESA performance in DOS is way more important than its 2D/GDI acceleration - few people would want to run vintage AutoCAD or QuarkXpress on this thing.
As for DVI / HDMI, the DVI spec was only finalized in 1999, so that's the earliest you will find any chip with support for it.
I wonder if anyone could get their hands on a supply of STPC Atlas SoCs. Those had integrated video, a 5x86 class processor, PCI, ISA, USB, and support for CRTs and TFTs - which would probably not have been too difficult to wire up to a DVI or HDMI transmitter.

I was outlining the goals of a the graphics acceleration if they were going to create something from scratch. Basically it was a wishlist of what a 486 graphics chip would be good to include when looking at it from a modern perspective.

If you want something off the shelf, Cirrus logic GD5429 or something similar is probably the easiest reasonable performance option.

Reply 99 of 116, by jakethompson1

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johnnycontrario wrote on 2020-08-29, 06:17:

Coincidentally, I found this product (probably unobtanium), that's almost exactly what I just described: https://www.esapcsolutions.com/product/esa-in … hared-pci-slot/

I have one, if there is anything you'd like to know about it.