I am currently reading From Nand to Tetris (aka The Elements of Computing Systems) - highly recommended. Anyway, in the last chapter (which deals with operating systems) it says:
Some functions are hardware supported (like addition) and are performed by the ALU, other functions are supplied with the programming language's libraries, and some are supplied by the operating system.
Which are the ones of the last type - operating system function? Can someone please give any example as to what functions modern OS supply?