operating system, OS = system operacyjny

Although the new OS

Source: http://www.videogamesblogger.com/2009/03/20/iphone-os-3s-new-game-related-features.htm

system operacyjny

English sentence and Polish translation

You need to install an operating system before you can run any programs. = Musisz zainstalować system operacyjny, zanim będziesz mógł uruchomić jakikolwiek program.