Unified Operating System
The unified operating system (UOS) is an operating system developed by RobCo Industries which manages the hardware of a computer and acts as a software environment in which computer programs can be run efficiently. It runs on a computer mainframe.
An operating system is essentially a software medium between the user and the computer hardware itself. The basic components of an operating system include the kernel, which controls the very basic processes like memory management, the execution of programs and drivers which handle networking with computer terminals and the sending and receiving of data to and from the keyboards, mice, monitors etc. which are connected to them. The operating system is also responsible for the user interface, i.e. what the terminal user sees on the screen. In the UOS's case, this is a command line interface. The UOS was published and copyrighted by RobCo Industries in 2075 with an expiration date in 2077.
- Before the unified operating system starts, a firmware BIOS called RobCo Termlink is run when a terminal is started which connects to the mainframe and initializes the operating system.
- According to this BIOS, the boot agent was copyrighted by RobCo Ind. in 2201 and expired in 2203. This is improbable, due to the fact that RobCo Industries or any sort of legal system necessary to patent something did not exist 124 years after the Great War. It's possible, though unlikely, that RobCo founder Robert House, still alive through stasis, had something to do with this.
- There are actually two operating systems shown in Fallout 3, one that has a green text interface with the patent expiring in 2077, the other with white text, with the patent expiring in the 2180s.
 Behind the scenes
The UOS bears a more than passing resemblance to the real world OpenVMS system, especially the terminals and terminal commands the Lone Wanderer can be seen typing in to hack into systems. The SET FILE/PROT= command is a valid VMS command, as well as the SET TERM/INQ command. The terminals themselves are labeled RT-V300 in the game, which probably means Remote (or RobCo) Terminal Video 300. The corresponding DEC (now HP) terminal would be a VT-300 terminal: Video Terminal-300. The RT-V300 terminals have the same "look and feel" (font, green screen, etc.) as the DEC VT terminals and look very similar to a DEC VT-100 terminal.