This is the SYSRESTORE.zip files for performing a "default SteamOS beta installation" see store.steampowered.com/steamos/buildyourown
With SteamOS, “openness” means that the hardware industry can iterate in the living room at a much faster pace than they’ve been able to. Content creators can connect directly to their customers. Users can alter or replace any part of the software or hardware they want. Gamers are empowered to join in the creation of the games they love. SteamOS will continue to evolve, but will remain an environment designed to foster these kinds of innovation.