In Unix-like operating systems, a device file system or special file system allows software to interact with a device driver using standard input/output system calls, which simplifies many tasks. It includes device files, device nodes, or device special files which are interfaces for a device driver that appears in a file system as if it were an ordinary file. There are also special device files on Microsoft operating systems, such as MS-DOS and Windows. Device files often provide simple interfaces to peripheral devices, such as printers. But they can also be used to access specific resources on those devices, such as disk partitions. Finally, device files are useful for accessing system resources that have no connection with any actual device such as data sinks and random number generators. MS-DOS borrowed the concept of special files from Unix, but renamed them device files. Because early versions of MS-DOS did not support a directory hierarchy, device files were distinguished from regular files by making their names reserved words.