sentence: the decreasing cost of display equipment and processors made it practical to provide graphical user interfaces for many operating systems , such as the generic x window system that is provided with many unix systems , or other graphical systems such as microsoft windows , the radioshack color computer 's os-9 level ii/multivue , commodore 's amigaos , atari tos , apple 's mac os , or even ibm 's os/2 .