Nice beast, a bit slow but decent, especially with the Super Turbo
option.
In talks with other hobbyists (and experience with my 4D/25 Super
Turbo), it seems like the Turbo option is a bit delicate, so you might
need to remove the turbo card and plug the RE1/RE2 into the slot (if it
is a 1988 model, then Turbo wasn't offered and won't be an issue). The
symptoms are graphics lockups. I haven't had time to look at my card
and se what's up.
It will run "IRIX" 4D1-3.2 through IRIX 5.3 just fine, note that to
install from a CD-ROM you need to have a SGI-firmware CD-ROM (there is
a hack in the firmware that has the drive identify itself to the SGI
PROM as a fixed SCSI disk long enough to trick the PROM into booting
from it), and you'll need to ignore the
"install system software" menu
option and instead go into the PROM
monitor, run "boot -f
dksc(0,<CD-ROM device ID>, 8)sash.IP6" and then at the sash prompt type
"install". IRIX 4.0 and above deal with CD-ROMs just fine, can't
remember about 4D1-3.x. For 5.3 you will want 32MB or more, look on the
old "SGI FAQ" for information on the endearing features of the PI 4D/2x
memory controller.