ile Management System Calls System calls related to the beam is indispensable. Like when we want to create or delete a file. Or when they want to open or close an existing file, reads the entire file, and write the file. System calls are also needed when we want to know the attributes of a file or when we also want to change these attributes. Which includes the file attributes file name, file type, and others. There are also system calls that provide another mechanism associated with the directory or file system as a whole. So not only deals with one specific file. For example create or delete a directory, and others. Device Management System Calls Running programs sometimes require additional resources. If many users are using the system, so if you need additional resources then it should ask for the device first. And after completion penggunakannnya be released again. When a device has been requested and allocated the device can be read, written, or repositioned. Maintenance Information System Calls Some system calls are provided to assist the exchange of information between the user and the operating system. An example system calls to request and set the time and date. Or request information about the system itself, such as the number of users, amount of memory and the disk can still be used, and others. There are also system calls to request information about the processes that are stored by the system and system calls to change (reset) the information. Communication System Calls Two models of communication: • Message-passing Exchange of information through inter-process communication facilities provided by the operating system. • Shared-memory The process of memory that can be used by different processes to exchange information to read and write data to memory. In message-passing, before the communication can be done must be built first a connection. This requires a system call in the connection settings, both in connecting the connection and the need to disconnect when the communication is completed. Also needed a system call to read and write messages (message) so that information exchange can be done.