I have received a 386 mainboard with OPTI chipset. Possibly an early model, since it does not support cache.

The chipset is labeled "82C381P" and "Chipset2".

OPTi 386 Mainboard

  • 5
    She's a beauty. Looks Taiwanese to me. Take her measurements and find her a nice tower to live in. – Brian H Jun 18 '18 at 15:16
  • Are there any other markings on the board itself? That may be a clue to helping figure out the manufacturer/model. – Rocket Hazmat Jun 18 '18 at 17:12
  • Also, what speed is the board? I'm guessing 25Mhz or 33Mhz? – Geo... Jun 18 '18 at 17:38
  • I can't find any markings on the board. On the back is a four digit number, but that looks pretty generic. The CPU is 33 MHz. – Arne Jun 18 '18 at 19:17

This is my best guess, but it looks really close. Could it be a Gigabyte GA-386PS?

This block diagram looks very similar:

enter image description here

I couldn't find the actual manual, but there are some jumper setting and connector details here

  • This looks really close! – Arne Jun 18 '18 at 19:17
  • I wonder what S1 is. It is supposedly a memory card slot... a quick search turned up nothing. – Arne Jun 18 '18 at 19:29
  • @Arne It seems to be a slot for external cache (Gigabyte-specific). Odd that it's so far from the CPU though. – Alex Hajnal Jun 18 '18 at 20:18
  • I think it would be remiss not to start from the observation that S1 has the exact same pin count and layout as the 16-bit ISA slots. That could just be because they were ordering those connectors anyway, of course. – Tommy Jun 18 '18 at 20:27
  • @Tommy A few things make me think it's for cache. 1) The 386 could use external cache modules 2) The modules weren't standardized 3) Gigabyte (still) offers a cache configuration utility for download (this implies that cache is supported but not included on the board) 4) There don't appear to be any cache memory chips on the board 5) The slot is right by the DRAMs 6) The linked document claims this is a 32-bit slot which seems sensible for cache of that era – Alex Hajnal Jun 18 '18 at 20:34

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