Hi ctully1,
IRIX runs a daemon called mediad that among other things is
responsible for automatically mounting your CDROM drive when
you insert one in and automatically unmounting it when you
issue an eject command (or use one of the GUIs to eject the
CD). The output of your mount command confirms that the CDROM is being mounted. By the way, df -k is another way of
checking what is mounted, and it will tell you how much free
space you have on your filesystems as well.
About your quake zip file, you should copy (cp) it off the CDROM onto one of your filesystems first. This is because gunzip will attempt to modify the file itself when unzipping (which is not possible with a normal CD). Once you
have the quake2.tar.gz file on a filesystem, do the following:
gunzip quake2.tar.gz (or whatever the filename is), from the
directory to which you copied the file.
tar -xvf quake2.tar
This will untar (extract) all of the indiviual files in the
tar archive. You will either have a working copy of Quake2
at this point, or an inst image. inst is the SGI installer
that you use when installing products on an SGI system.
If you see files with .idb extensions, you probably have
an inst image. Just use inst to install.