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Operating Systems Software Icons key: For more detailed instructions, see the Getting Started presentation Flash activity. These activities are not editable. Teacher’s notes included in the Notes Page Web addresses 1 of 18 © Boardworks Ltd 2007 Learning objectives Understand what an operating system is and its main functions. Know the main operating systems used today. Learn what an interface is and about the widely used types of interface. 2 of 18 © Boardworks Ltd 2007 Operating system What is an operating system? An operating system (or OS) is a computer program which controls everything the computer does. New computers usually come with one installed. You cannot use any other program (software) without an operating system. 3 of 18 © Boardworks Ltd 2007 Yes, but what does it do? You probably don’t think about it, but while you’re doing the interesting stuff, your operating system is: handling communications between software and hardware allocating computer memory and managing CPU time organizing how data is stored on backing storage. 4 of 18 © Boardworks Ltd 2007 Communicating At any one time, your computer might be: loading and saving data and programs communicating with peripherals such as a mouse or a printer displaying information on the monitor. The operating system has to communicate with the hardware and software and manage the tasks. This prevents the system from trying to do things like read from and write to a USB memory stick at the same time. Because the operating system manages what the software does, most pieces of software need a particular operating system to be able to function. 5 of 18 © Boardworks Ltd 2007 Managing computer memory Even though you think you are only doing one thing on your computer, like working with a spreadsheet, computer memory must be allocated to each task the computer is doing. Computer memory is used to: store the spreadsheet program store your spreadsheet file store a copy of the image that is being displayed on the monitor run the operating system. 6 of 18 © Boardworks Ltd 2007 Allocating CPU time If you were printing the first page of your spreadsheet while working on the second one, the CPU’s time would need to be divided up between: letting you enter more data on the keyboard printing sheet one displaying what is going on via your monitor. The operating system helps to manage which tasks take priority. 7 of 18 © Boardworks Ltd 2007 Two processors are better than one The operating system splits CPU time into tiny slices and allocates each task some time, so it appears as if the computer is doing many things at once – multi-tasking. Older computers only have one microprocessor in their CPU, so can only do one thing at a time. Newer computers have dual core processors, with two cores on the same chip, each processor having its own cache. This is like having two CPUs instead of one, so the system works much faster. 8 of 18 © Boardworks Ltd 2007 Types of operating systems 9 of 18 © Boardworks Ltd 2007 Interfaces An interface is the means by which a user can interact and exchange information with the computer. There are four main types of interface: command line interfaces (CLI) menu-based interfaces graphical user interfaces (GUI) 10 of 18 © Boardworks Ltd 2007 Command line interface Older operating systems such as MS-DOS are often called command line interfaces, or CLIs. They are text based, and the user has to type in what they want to do using commands the computer will understand. They work very quickly, and don’t use up many system resources such as memory or hard disk space, but they are difficult to use unless you know the commands really well. 11 of 18 © Boardworks Ltd 2007 Menu-based interface 12 of 18 © Boardworks Ltd 2007 Graphical user interface GUIs, or graphical user interfaces, are also easy to use. They use pictures called icons to represent files or buttons, and the user clicks on the button with a pointer moved by a mouse. Windows XP, OS/X and Linux are all GUIs. Many touch-Screen information panels also use GUIs. 13 of 18 © Boardworks Ltd 2007 Graphical user interface This isn’t a real calculator, it’s a GUI that represents one. Press the buttons below and see what happens. The interface converts the clicks into a code for us. Clicking on icons with a mouse or pointer is much easier than having to type in the numbers for the calculation in a format the computer will understand, as would happen in a CLI. 14 of 18 © Boardworks Ltd 2007 Mobile phone interfaces Mobile phones can have menu-based interfaces or GUIs: This mobile phone is menu driven. Applications are selected using the phone’s keypad. 15 of 18 This phone has a GUI. It has icons to represent applications, which can be selected. © Boardworks Ltd 2007 WIMP In computing WIMP stands for: Windows, Icons, Menus, Pointer. Most WIMP interfaces are also GUIs, but the use of windows and menus make them stand apart from more basic forms of GUI. Most modern operating systems use the WIMP interface. 16 of 18 © Boardworks Ltd 2007 WIMP environments 17 of 18 © Boardworks Ltd 2007 Summary An operating system (or OS) is a computer program which controls everything the computer does. The operating system handles communication between software and hardware, allocates computer memory and CPU time, and organizes how data is stored on backing storage. The operating system helps to manage which operation gets priority when multi-tasking. There are three types of interfaces: command line interfaces (CLI), menu-based interfaces, graphical user interfaces (GUI). WIMP (Windows, Icons, Menus, Pointer) interfaces are a type of GUI. 18 of 18 © Boardworks Ltd 2007