IRIX was the operating system developed by Silicon Graphics, Inc. (SGI) to run natively on their MIPS workstations and servers. It is based on UNIX System V with BSD extensions. IRIX was the first operating system to include the XFS file system.The last major version of IRIX was IRIX 6.5 which was released in May 1998. New minor versions of IRIX 6.5 were released every quarter until 2005; since then there have been four further minor releases.