Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Discussion about old PC hardware.

Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby adalbert » 2018-1-03 @ 21:21

Well, I guess that it would be only possible (without extremely high costs) to make such a simple board, like this 386SX:

https://www.recycledgoods.com/forcom-te ... therboard/
https://www.philscomputerlab.com/forcom-m396f.html
Image

It's just a 2-sided board (you can see that it's transparent inside, no internal traces, blurred traces from the other side are visible), only 6 chips (2 SMD, 4 THT, no BGA) and less than 100 discrete components, all of them are THT type, so they could be even soldered by hand. PCB probably would be easy to manufacture, but someone would have to re-design it. Or remove all components from a single board, remake it and steal the design... :P
That chipset was available on AliExpress https://aliexpress.com/item/SARC-QFP208 ... 99996.html for 12USD, but it's out of stock now. Components would be probably hard to get. But it should be possible to make, it looks even less complicated than a PC-XT clone (Sergey's XT). But difficulty level would rise exponentially while increasing PCB complexity.

But that's just a 386SX without cache, it sucks :P

//update: here you can buy that chipset for 13.54USD
https://www.utsource.net/itm/p/1725835.html
keyboard controller: 1.28 USD
https://www.ebay.com/i/222106201158?rt=nc
RTC: should be easy to get, 3-10USD
https://www.ebay.com/itm/M5818-AI-9315- ... SwPhdU9YlB
TK9207 ~2USD/piece
https://aliexpress.com/store/product/TK ... 69163.html https://www.utsource.net/itm/p/1384137.html
BIOS? well, the EPROM should be pretty cheap, but the software should be licensed...
Brand new 386SX CPU? that's hard to obtain, more expensive than used ones, around 50USD
http://www.ebay.co.uk/itm/AM386SX-SXL25 ... SwsWpZ4gOZ

Well, other componens could be easily sourced from local electronic stores, someone could try to copy that design, but honestly I don't want to try doing that :P
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby Deksor » 2018-1-03 @ 23:46

I'm pretty sure you could source 386SX CPUS from dead mobos that sufferred battery leakage. Actually, I'm kicking myself to upgrade my 386SX25 to 386SX33 since I've got a dead mobo with that CPU mounted and that the other mobo works and can support 33MHz CPUs (although I'm pretty sure the CPU would support the OC, so that should be less risky ^^)
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby mdfverona » 2018-1-07 @ 23:30

So the vortex86DX 800Mhz at min clock is WAYYYY to fast for stuff like wing commander 2, I tried moslo and a slew of other utils and they made it playable but all jerky to control, I guess based on the RTC being like 18 cycles/s. So looked at the vortex86 dev guide, and since its an industrial part it has some neat features in the SoC including two watch dog times with 30.5us max count resolution. One of the timers is known by the BIOS and one is not, so NO GAME WOULD EVER KNOW TO USE IT.

I did a crash course in DOS interrupts and TSRs and now have the 2nd timer triggering an interrupt every 210us and my TSR doing some stupid character array compares to delay a bit, and WC2's cutscenes now line up with the speech, and the mouse and action does not lag at all. Its far from a complete project, but is working great now. Needs more tuning and my TSR is kind of a mess in Borland C instead of ASM, but for me at least it validates that the Vortex86DX parts that are commonly available now are workable for legacy gaming thanks to the extra features in the SoC.

Attaching the source and exe, for now just doing "wdcslow /i" on a Vortex86DX 800Mhz set to the lowest bios allowed clockspeed makes WC2 awesome. Its a total work in progress and my first DOS interrupt/TSR project, thankfully a lot of the port stuff was available in the Vortex guide to get me started. I was rushing to see if it could work better than the existing utils so I do some really dumb stuff to take up process time during the interrupt and I think I left it hard coded to IRQ 15. I noticed a speech dropout here and there, so think first change before doing some more play testing is to pick a lower priority IRQ than the sound card. Compiles in Borland C++.
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WDCSLOW.EXE
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby amadeus777999 » 2018-1-08 @ 17:05

mdfverona wrote:So the vortex86DX 800Mhz at min clock is WAYYYY to fast for stuff like wing commander 2, I tried moslo and a slew of other utils and they made it playable but all jerky to control, I guess based on the RTC being like 18 cycles/s. So looked at the vortex86 dev guide, and since its an industrial part it has some neat features in the SoC including two watch dog times with 30.5us max count resolution. One of the timers is known by the BIOS and one is not, so NO GAME WOULD EVER KNOW TO USE IT.

I did a crash course in DOS interrupts and TSRs and now have the 2nd timer triggering an interrupt every 210us and my TSR doing some stupid character array compares to delay a bit, and WC2's cutscenes now line up with the speech, and the mouse and action does not lag at all. Its far from a complete project, but is working great now. Needs more tuning and my TSR is kind of a mess in Borland C instead of ASM, but for me at least it validates that the Vortex86DX parts that are commonly available now are workable for legacy gaming thanks to the extra features in the SoC.

Attaching the source and exe, for now just doing "wdcslow /i" on a Vortex86DX 800Mhz set to the lowest bios allowed clockspeed makes WC2 awesome. Its a total work in progress and my first DOS interrupt/TSR project, thankfully a lot of the port stuff was available in the Vortex guide to get me started. I was rushing to see if it could work better than the existing utils so I do some really dumb stuff to take up process time during the interrupt and I think I left it hard coded to IRQ 15. I noticed a speech dropout here and there, so think first change before doing some more play testing is to pick a lower priority IRQ than the sound card. Compiles in Borland C++.


Very nice!
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby Kubik » 2018-1-10 @ 13:16

Anyway, back to the topic - what about this? http://www.nvidia.com/page/uli_m6117c.html
It's 386SX with chipset in one package, so it should be fairly simple to design a CPU board around it (perhaps even two layers only), and use some sort of passive backplane. That would keep the board price low, and I am sure that there are passive backplanes around already that could be just reused.
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby Cyberdyne » 2018-1-14 @ 08:13

I have a small 4 slot isa backplane and i am just looking for a good small isa sbc for my future projects.
I am aroused about any X86 stuff that has full functional ISA stuff. I think i have problem.
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Re: Dudes it is time to make a MOTHERBOARD, i know it wil cost dearly, but i will buy it!

Postby Auzner » 2018-1-14 @ 08:52

https://blog.lse.epita.fr//articles/77-lsepc-intro.html
I like where this is going. Just have a 386SX-20 paired with an FPGA. Customize the chipset and IO.

https://www.digikey.com/products/en/int ... V=ffe002b6
https://www.digikey.com/products/en/int ... eyword=486

A "186" built in an FPGA! https://www.jamieiles.com/80186/ Gives a lot of flexibility for what you could add on.
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