386 w/UNIX jumper??

From: Doug Yowza <yowza_at_yowza.com>
Date: Mon Jun 29 17:53:54 1998

On Mon, 29 Jun 1998, Russ Blakeman wrote:

> As usual, no docs. This is not a problem as most is self explanatory.
> There is one jumper on the mainboard though that goes in either 1-2 or
> 2-3 that's marked "Unix", nothing else. Anyone have any idea what this
> would do? I've moved it but nothing,but I haven't loaded Unix on it
> either.

For years, while Microsoft sat on their real-mode butts, Unix was the only
thing that would take advantage of 32-bit protected mode on the 386. So,
most PC manufacturers didn't even bother to test their designs in a 32-bit
environment. When somebody tried to run a 32-bit Unix on these boxes,
there was a fair chance it didn't work (either due to a buggy rev of the
386, or to some braindead address masking done on the mobo). So, I
suspect that the jumper disables some 86/286-style address masking to
enable full 32-bitness (for which Unix was the only known user at the
time).

If I wasn't out of space, I'd want one of those boxes just for that
interesting anachronism.

-- Doug
Received on Mon Jun 29 1998 - 17:53:54 BST