It looks like an modern version of Linux running with Xorg. We can see that the GNU flavor of "top" is running (shows the running process, memory utilisation, etc. In the image, the system is reporting an uptime of 8 days) as is the Linux version of "iostat" (Input/Output Statistics). There is also both an on-screen keyboard and orange power controls in the lower right corner, just like those built into Dillinger's Desk.
In contrast to a standard Linux system, the shell appears to be configured to not display the PS1 variable, and logging in as root displays a warning about no home directory being set (this is uncommon on a linux system, but is often seen on systems like SunOS/Solaris).
- It is a direct reference to the Sun OS or Sun Solaris OS, that is Unix based. Probably due to copyright issues the real name wasn't used.
- After Sam determines the active username and operating system (with the 'whoami' and 'uname' functions), he uses the 'history' command to reveal the last commands executed (twenty years earlier).
- The directory /opt/LLL/controller likely refers to the location of shooting in the original TRON movie. The laser bay shots (and several others) were all filmed at Lawrence Livermore National Lab (LLL).