Operating Systems

An operating system is a collection (or suite) of programs that manages and controls the computer. Operating systems have many functions:

controlling hardware components
providing a platform for software to run on
providing a user interface
multitasking facilities
managing the computer's memory
managing peripherals
managing files
managing users

Example operating systems include:

Microsoft Windows
Apple OS X
Linux
Android
IOS

User Interfaces

Graphical user interface (GUI)

A graphical user interface is familiar to most users of PCs and laptops. GUIs feature a desktop where everything is displayed. Applications run in Windows, and all objects (apps, hardware and files) are represented by icons. Application features are accessible through the use of menus. Users interact with the interface by using a mouse and on-screen pointer.

GUIs are powerful and easy to use, but require a lot of processing power.

Spiderman enjoying the menu-driven ipod

Menu-driven interface

A menu-driven interface is a type of graphical user interface (GUI) that allows users to interact with a computer program by selecting various options from a list of choices displayed on the screen. In a menu-driven interface, the user navigates through a series of menus, each containing a list of options to choose from, until they reach the desired function or task.

Spiderman utilising windows' WIMP interface

WIMP interfaces

User can click on icons using a pointer or cursor

Icons representing functions mean less need to type instructions – just click on an icon or menu item

Right-clicking brings up context-sensitive menus

Different shaped pointers have different uses

Command line interface

Command line interfaces are text-based. Users control the computer by typing in commands.

CLIs require little processing power and are extremely powerful, but are difficult to use. Originally most interfaces were CLIs, and they still exist within modern operating systems, for example the command prompt app in Windows, and Terminal in OS X.

Multitasking

Multitasking means being able to run more than one program at a time, for example streaming music while downloading a new game you got on steam that you'll only play once.

Multitasking is possible only if:

the operating system can support multitasking
the computer has enough memory to hold more than one program in primary memory at the same time

Memory Management

Computer memory must be managed to ensure that:

more than one program can run at the same time
more than one document can be opened at the same time

Peripherals and drivers

Peripherals are hardware devices connected to a computer, such as a monitor, printer, scanner or camera.

To operate a peripheral, the operating system uses a program called a device driver. Device drivers contain instructions on how to control a device. Each connected device has its own driver.

Using device drivers brings two advantages:

any device can be used with the operating system, as long as a driver is available for it
drivers can be updated, usually to give better performance or to remove a bug

Art style for this page - Graphic Novel art

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