Note that even if you do try to skip this step, you may still need to load
extra software to get enough of an environment to allow "after" to function
properly. In particular, for IRIX 6.3, you may need the ONC/NFS CDROM; I
installed everything on it.
The full install is optional, but... It's generally preferable to know
what's installed, instead of just taking whatever the vendor happened to
think was "good enough". A little extra trouble now, to install the OS from
scratch, can save us from some really dumb little problems in the future, due
to the lack of true commonality. Then again, in the case of SGI's, you
never know
when the vendor is going to preload something that you can't get from
one of our CDROM's, so either do a full backup before reinstalling from
scratch, or skip the step of loading the software from CDROM.