[robespierre]

I don't think that writing a full functional specification (which is a necessary step in clean room engineering) for a Unix kernel is even practical for the amount of money described. It is much less than companies spent to reverse-engineer the IBM PC BIOS, for example, yet the system is several orders of magnitude more complex.

Just about everything anyone does with IRIX these days is a copyright violation. From websites that host documentation or man pages, to hobbyists burning copies of media to install on their SGIs, the whole ecosystem is unlicensed. If the shrinkwrap license posted above is legally enforceable, then there is no "right to use" simply because you own hardware. The license is nontransferable unless you signed a contract with the original purchaser to assume all of the responsibilities of the license (I don't think anyone ever did that). Note however that 1998 is the date of IRIX 6.5 and the license for 5.3 was almost certainly much different (jurisprudence around shrinkwrap licenses was highly uncertain through at least 1996).