R3K SGI Indigo & installing IRIX 5.3

Blah! OK, the Indigo doesn't like my old Apple SCSI CDROM drive, even though the Indy and my Sun Ultra 1 do... luckily I had a spare quad-speed drive which has a sector-size jumper on the back. (So it wasn't a bad SCSI cable or a problem with the Indigo's external SCSI connector as it turns out) Anyway, I'm just trying to get IRIX 5.3 from CD onto a disk in the Indigo (one which currently has a mangled copy of 5.3 on it). I've used the same CD to install 5.3 on the Indy previously - just not tried it with the Indigo... If I go view the PROM monitor and select "Install System Software", then use the CDROM as the source device, it copies the installation program to disk, says complete, but then dies with: "Unable to load dksc(0,1,1)unix.IP12: file not found" I seem to recall the Indy doing the same thing, which I think was a disk partition problem (as in that case I was installing onto a drive that had previously been in a PC) So, I restarted at this time went into the PROM monitor's command monitor and did: "boot -f dksc(0,6,8)sashARCS dksc(0,6,7)stand/fx.ARCS" ... which was what I used for the Indy to partition the drive. On the Indigo it just blows up with: 72912 NESTED EXCEPTION at pc: bfc11d90, first exception at bfc11d90 Any ideas what I'm doing wrong? Given that the Indigo's an R3K and the Indy is an R4K, do I need a different boot command to load the relevant R3K software? I know this Indigo works - but the release of 5.3 is a copied version that came with the Indy... maybe it's missing something I need, or maybe SGI did different 5.3 releases for R3K and R4K machines? cheers Jules