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 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.