This is perhaps a bit off-topic for the port-i386 mailing list, but I
think it's still relevant to be worth posting here.  I'm currently
running NetBSD/i386 on a 486DX2/66 ISA/VLB motherboard.  My video card
is a fairly old ISA ET4000-based card, and with the impending release
of XFree86 3.1.2 (which will support the new #9 and Diamond cards), I
was hoping to upgrade to a faster card.

I've noticed, though, that VLB appears to be on its way out and PCI is
the way to go.  Since I have a VLB motherboard, I was thinking that I
should upgrade to PCI and get a PCI video card, rather than buying a
VLB card that I would probably have to replace if I upgrade to a
Pentium later on.  However, I don't want to upgrade to a Pentium yet;
the 486DX2/66 is still plenty fast for me most of the time, and I
don't really have the cash to buy a Pentium CPU on top of all the
other upgrades.

So, my thought was that I could buy an ISA/PCI motherboard without a
CPU and transplant my 486DX2/66 CPU into it.  (My current motherboard
has a ZIF socket, so that shouldn't be too hard.)  It would be nice if
whatever motherboard I got could also take a Pentium at some point, so
I don't have to change motherboards yet again if I want to upgrade my
CPU.  But I know next to nothing about the internals of Pentium
and PCI motherboard architecture, so I'd like some advice about this.
Specifically:

* Does this plan sound reasonable?  Are Pentiums so cheap that it
might be better to get a Pentium motherboard and sell the 486DX2/66
CPU with the motherboard, rather than steal the CPU and end up with a
practically unsellable motherboard without CPU?  (A quick glance
through Computer Shopper makes me not think so, but I might have
missed something.)

* Will I take a performance hit by getting a motherboard that supports
both a 486DX and a Pentium?  Do such motherboards even exist?

* Will such a motherboard be able to run NetBSD without any problems?
(Random system crashes, data corruption, kernel panics, etc. all
qualify as "problems".  I am running 1.0A, though, so if there were
problems which have since been fixed in -current that's okay.)

* Are there any general features I should look for when motherboard
shopping?  i.e., chipsets to look for or stay away from, BIOS revision
gotchas, etc.

* Does anybody have information on specific motherboard brands or
vendors?  Both positive recommendations and "stay away from XXX"
warnings are appreciated.

Ideally I would like a motherboard with two built-in 16550 serial
ports, a built-in parallel port, and a built-in NCR SCSI host adapter.
(I've gathered that the NCR SCSI chip is the one to use with PCI, but
if that's not the case then replace "NCR SCSI" with "any other PCI
SCSI that works well with NetBSD.")  I have no desire for built-in
VGA.  All but the SCSI chip seem to be pretty standard, but most of
the motherboards I see advertised have EIDE built in rather than SCSI.
Does anybody sell a 486/Pentium PCI motherboard with built-in SCSI
that works under NetBSD?

The other point I've thought of is RAM...Currently I have 20MB of
30-pin SIMMS (only 16MB in the machine, though, since I'm using an ISA
Adaptec SCSI adapter).  A lot of the newer motherboards seem to be
using 72-pin SIMMs, and some of them use "weird" (EDO, etc.) RAM.  Is
trying to get a PCI motherboard where I can continue to use my 30-pin
SIMMs possible, or should I resign myself to replacing my memory?

Thanks for your advice...

-Marc