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wanted: 80486 motherboard or laptop/notebook schematics

Well keep us in mind if after a few months we're done with Phase 1 Linux-SBC it would be a good starting point to finish & integrate your design into the board for Phase 2.

Yes, 4GB for a 486 is a lot but I think 1 GB to run a semi-modern Linux is within the realm of possible.

The Linux-SBC Phase 2 goal is to integrate 1GB of SDRAM into the design and your solution sounds like it would accomplish just that.

Assuming we get that far, of course. We have to get the Phase 1 board working first. The 82C465MVB supports up to 64MB DRAM (CPU address lines CA0-CA25 only) which is enough to run some barebones Linux distributions like DSL, Puppy Linux, etc.

Thanks, Andrew Lynch
 
zombienerd said:
You can thank the Romanians. One of their college laboratories had the schematics archived with the original Intel file name. Combination of combing intel's website on the wayback machine, and some index of searches finally hit that paydirt.
Click to expand...

Well, I'll thank you for finding it. I swear I searched high and low and found almost nothing until you turned this up. I can't wait to review it tonight! THANKS! Andrew Lynch
 
zombienerd said:
I distilled the Postscripts into PDF, 11x17 size, very readable. I don't have Orcad 3.22 either, so I can't open the originals to see if there's anything that wasn't in the PS files, but it's a start.

https://www.dropbox.com/s/1zeonwed749kl6c/intel 486sx devboard PDFs.rar?dl=0

You can thank the Romanians. One of their college laboratories had the schematics archived with the original Intel file name. Combination of combing intel's website on the wayback machine, and some index of searches finally hit that paydirt.
Click to expand...

The postscript schematics in the package were.. eh.. bleh. I converted and scaled them to a single PDF here. Might save some others from doing the same work.

https://www.retrotronics.org/vcf/ULP486sx.pdf
 
eeguru said:
The postscript schematics in the package were.. eh.. bleh. I converted and scaled them to a single PDF here. Might save some others from doing the same work.

https://www.retrotronics.org/vcf/ULP486sx.pdf
Click to expand...

Nice. Yeah, much better than my quick "Throw them through distiller" Thanks! :) I did some quick googling, and it seems those chipset IC's are still out there in large quantities, as well.
 
I've looked over the recent find of 486 motherboard schematics and am very impressed. The low power Intel 486SX approach is now the backup plan in case using the 82C465MVB chipset fails for whatever reason. It is a nice clean simple design that can be scaled. Perfect for what I'd like to do! Thanks Zombienerd!
 
Wow, I've been reading the ULP486SX design and it is fascinating. Great schematic too. What a great board. I wish I'd known about this before designing the current Linux-SBC board as it would have made it much easier. Still it is a great comparison. Both designs being AT ISA, 486, DRAM with an integrated chipset there are a lot of similarities. However, Intel is still in business (OPTi RIP) and the parts are apparently still plentiful.

It reminds me of co-evolution. I started with the 82C465MVB datasheet with no reference schematic and ended up designing an AT ISA board which is *very* similar to the ULP486SX. They are scary similar like brothers but I did not know about the ULP486SX until afterward after the Linux-SBC design was complete. Trim away the extraneous ULP486SX peripherals and you have a Linux-SBC. Weird...
 
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I have pentium 1 laptop schematics for the Alphatop Green 755 (plus Green 753 and Green 753+) which all used some Opti chips, I believe. Plus a bunch of motherboards for the same if there's any useful chips that's common with your needs. Also, Chicony P1 and P2 laptop mobo's that also might have Opti chips.
 
Thanks Al! That's great. I've already ordered the Derpy Linux-SBC prototype boards so they should be here in a week or so. Our options at this point for a 486 home brew computer are to 1. make Derpy work (OPTi 82C65MV), 2. redesign based on Intel pico power ULP486sx design, or 3. redesign based on the SIS 85C460. It certainly is nice to have some options! Even if the OPTi 82C465MV is able to function it may or may not prove to be suitable for whatever reason so it is good to have a fall back plan.

Your help is greatly appreciated! Thanks, Andrew Lynch
 
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