Functions+of+an+OS


 * Input and Output Control**
 * OS controls the transfer of data within the computer or between other linked devices. It makes sure the application software functions run smoothly.


 * Error Handling**
 * The OS receives signals of errors, interprets it and displays a message on the screen that informs the user about it.
 * Errors the arise when a program is running are called **run time errors**.


 * Resource Allocation**
 * Controls the running and scheduling of **processes** that need different types of resources in order to run. Ensures that all of the resources needed to run a software successfully are ready to use.
 * Parallel processing means two or more processes running at a time. (Multitasking)


 * Commands and User Interfaces**
 * **Command Line User Interfaces**
 * Users type in the exact command on a command line.
 * Command line is very straightforward and quick to use if you know all of the commands well.
 * Instructions are available but time-consuming to read.
 * **Menu-Driven User Interfaces**
 * A drop-down menu which displays options a user can choose and select by pressing enter.
 * Easy because you don’t have to remember commands.
 * Irritating to move through a whole **hierarchical** menu.
 * **Graphical User Interfaces**
 * The user chooses an icon or menu option that represents a program with a pointing device such as a mouse.
 * GUIs are very user-friendly, easy to operate and understand.
 * Menu bar
 * Drop Down Menus
 * Sub menus
 * Toolbars
 * Scroll Bar
 * Dialog Box


 * File Handling**
 * Allows users to name, save, delete, copy, paste, move, format files or disks.
 * Extensions identifies the type of document it is.
 * Root / Directories / Sub Folder
 * Properties shows if the file is read only, hidden etc.
 * Formatting sets up the tracks on a hard disk and divides them into sectors.


 * Utilities**
 * Utility programs help to maintain the computer and it’s applications to more smoothly.
 * Disk Defragmenter will reassemble all the different parts of all the files.


 * Help Documentation**
 * A printed manual, online help, telephone help line.
 * How to use the software, hardware requirements, how to get more information and further help if you need it, how the software is structured.