lo1-what is the purpose and functionality of system software? 

There are two main type of software that are used on computer system;

these are system software and application software.  System software controls the operations of hardware in a computer system. 

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Systems software also provides a platform to run applications software. 

Applications software is the everyday programs we use to create document and carry out communication with each other using technology. Some examples of applications software include Internet Explorer, Paint and Microsoft Word. 

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There are a number of type of system software, such as device drives, Utility software and the operating system. 

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Operating system  

An operating system ( or 'OS') is a collection of software designed to act as an interface between the user and the computer and manages the overall operating of the computer. It links together the hardware , the applications and other software-  so called Virtual machine.  

On some computers it is possible to run a choice of operating systems. Games consoles have their own unique operating systems. There are a few common operating systems available:

• Mac OS X

• Linux

• Windows

• Android (based on Linux)

• iOS

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The operating system looks and oversees such thing as:  

• managing the computer hardware and peripherals and controls print queues.

• managing programs installed and being run i.e. the start up configuration of your computer, including what icons to put on your desktop and what backdrop to use. 

• recognises when you have presses a mouse button and then decided what, if any, action to take.

• managing data transfer between memory location, the CPU and secondary storage  sends signals to the hard disk controller, telling it what program to transfer to memory

• decide which sections of memory to allocate you are intending to use and manages memory to ensure all the program you want to run are allocated the space they need 

• attempts to cope with errors as and when they occur, for example, if a printer send an 'out of paper error' or you fail to save a file correctly, it is the operating system that displays the appropriate message

• managing security and organising data so that it is not overwritten for example, it maintains the lists of usernames and password and controls which files and resources users have access to. 

• make sure that your computer shuts down properly when you have finished

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User interface 

A user interface is the method by which the user and the computer exchange information and instructions. There are three main types: command-line, menu driven and graphical user interface (GUI).

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A Graphic user interface (GUI)

Is the most common type if interface we use to interact with computers. it has a lot of icons, menus and windows for the user  to click and open.  This type of operating system is used for many devices like personal computers, smartphones and tables. 

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Use 4 basic features (WIMP)

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◦Windows

◦Icons

◦Menus

◦Pointers

Often called a WIMP environment

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Command-line interface (CLI) 

An OS also provides a method of interaction that is non-graphical, called the command line interface (CLI). This is a text-only service with feedback from the OS appearing in text. Using a CLI requires knowledge of the commands available on a particular machine.

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The features of Command- line interface:

• Commands must be typed correctly and in the right order or the command will not work.

• Experienced users who know the commands can work very quickly without having to find their way around menus.

• An advantage of command driven programs is that they do not need the memory and processing power of the latest computer and will often run on lower spec machines.

• Command driven programs do not need to run in Windows.

• A command-line interface can run many programs, for example a batch file could launch half a dozen programs to do its task.

• An inexperienced user can sometimes find a command driven program difficult to use because of the number of commands that have to be learnt.

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Natural- language interface (NLI) or Voice input

A user controls a natural- language interface through the use of linguistic commands  that are often spoken. The user can use of everyday words and phrases to interact with the computer and perform tasks. People make use of NLIs as they can potentially be a very quick and easy way of giving commands to a computer system. However, in practice, the ability of a NLI to  understand most commands can often ambiguous and can frustrate the user. A common example of a NLI is Apple's Siri. This NLI makes use of the natural- language processing to answer questions, perform tasks and make recommendations. 

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Craig Mundie is Microsoft's big thinker "the computer is more like us - it sees, it listens, it speaks, it understands, it even seeks to do things on our behalf."

http://www.bbc.co.uk/news/business-12570045

27th Feb 2011

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Menu driven interface

Useful in situations where the user needs to be restricted to a limited choice

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To consider

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• Balance between options on a screen at one time and number of levels of sub-menus required.

• Should have a consistent layout.

• Should use the same prompt for the same operation (e.g. back button).

• Prompt should be in the same position on the screen

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