> What I see are 3 chips:
> ALI M1451
> ALI M1449
> CMD PCI0640B
> 
> Maybe PCI Explorer is confusing Vendor ID 10B9 with "ACER" instead of "ALI"

Don't know.. What chipset is your mainboard supposed to have?  Like 'triton',
or 'SiS', or whatever?  As PCI Explorer is somewhat old, it probably doesn't
know about every new P5 chipset.

> If the Mach64 is not recognized as a PCI device, what is getting recognized as
> 
> 	pc0 at isa0 port 0x60-0x6f irq 1: color

A Mach64 (and just about any other PC video accelerator out there) has a
VGA card *and* a SVGA/accelerator aspect.  Basically it looks just like a
ISA VGA card to the PC.  Otherwise the PC BIOS would get confused as they
only understand about generic ISA video devices.  Pccons doesn't know about
PCI video either, as it talks to the ISA VGA emulation aspect of the card.
The early TIGA (Texas Instruments Graphics Architecture) boards exemplified
this behavior well.  The cheaper ones had to be plugged into the VGA feature
connector to allow 'VGA passthru', or you had to have 2 monitors.
(better TIGA cards had/have a VGA daughterboard)

> Will I be able to get XFree86 to run on the Mach64 if it's coming up as
> "not configured"?  I guess for some weird reason I would have expected to see
> something like
> 
> 	pc0 at pci0 bus 0 device 6: ATI Mach64, <...>: color

XFree86 will work fine.  Currently NetBSD itself doesn't care too much
about the accelerators as it doesn't use them.  If some kind of board
or machine independent framebuffer approach was used with X, then perhaps
you would need a Mach64 driver _in the kernel_.

> (As you can see, a SPARC person can generate a lot of PC questions  (-: ).

That's 'cuz the PC architecture was designed to run DOS.  Those of us
that want to run unix on it have to suffer. :)

-Andrew