I was poking around SGI's Techpubs site today, looking for an IRIX 5.3-era man page, and I noticed that versions of IRIX prior to IRIX 6.5 are no longer listed in the Techpubs navigation links. However, SGI still has the pre-6.5 documents available through Techpubs as "archive" material. For your convenience, here are the links to the version-specific sections of the Techpubs archives:
IRIX 5.3 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0530
IRIX 6.2 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0620
IRIX 6.3 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0630
IRIX 6.4 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0640
For those who might be interested in creating their own, personal archives, there was a fair amount of discussion on the subject in this thread from a couple of years ago - viewtopic.php?f=10&t=10071
IRIX 5.3 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0530
IRIX 6.2 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0620
IRIX 6.3 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0630
IRIX 6.4 - http://techpubs.sgi.com/library/tpl/cgi ... ?coll=0640
For those who might be interested in creating their own, personal archives, there was a fair amount of discussion on the subject in this thread from a couple of years ago - viewtopic.php?f=10&t=10071