INFO 2 CH15 - People and ICT Systems User Interfaces

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What is an Interface?

What is an Interface?

An interface means a connection between two things. In this case these are connections, or means of communicating between a user and an ICT system.

What is an Operating System? 

An operating system is a very complex program which controls the hardware within the computer and allows communications between pieces of hardware and between hardware and users. The interface is the mechanism by which the user controls the operating system.

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What types of Interfaces are there?

There are 7 different types of interfaces:

  • Command-Line Interface
  • Menu-Driven Interface
  • Graphical User Interface
  • Form Driven Interface
  • Dialogue Interface 
  • Natural-Language Interface 
  • Touch Sensitive Interface 
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Command-Line Interface

Is an interface where the user types in commands for the computer to interpret and carry out. As a command is typed in, it appears on the screen. The user has to know the commands and there are no clues to help guess them.

The MS-DOS operating system uses a command line interface. The screen is usually blank and C:> (called the C prompt) appears on the left of the screen. This means that the computer is looking at drive C, the internal hard drive. Any file references typed in refer to that drive.

Many commands are complex. There may be additional parameters, usually extra letters at the end of the command that modify its meaning. 

Little computer memory is required for a command-line interface. Precise sequences of instructions can be entered allowing complex tasks to be performed. The user has to learn all these commands. As a result command-line interfaces are normally only used by experienced and expert users. 

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Command-Line Interface 2


  • If the user knows the correct commands then this type of interface can be much faster than any other type of interface
  • This type of interface needs much less memory (RAM) in order to use compared to other types of user interfaces
  • This type of interface does not use as much CPU processing time as others
  • A low resolution, cheaper monitor can be used with this type of interface
  • A CLI does not require Windows to run


  • For someone who has never used a CLI, it can be very confusing
  • Commands have to be typed precisely. If there is a spelling error the command will fail
  • If you mis-type an instruction, it is often necessary to start from scratch again
  • There are a large number of commands which need to be learned - in the case of Unix it can be hundreds
  • You can't just guess what the instruction might be and you can't just 'have a go'.
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Menu-Driven Interface

A Meun Driven interface has elements of a GUI and a CLI. You get a selection of options to choose from in a menu. Each option is a command but you don’t need to learn them because you can click on one that you want. 

A Menu-Driven user interface displays a set a choices on the screen so that the user can make a selection from the range of choices offered. They can operate in a number of ways:

  • The selections may be numbered and the option selected by pressing a number key
  • The user may scroll through the selections using the cursor keys or a mouse until the required option is highlighted and then press enter
  • If a touch screen is used, the user touches the screen at the place where the chosen option appears.

Choosing an option may lead to a sub-menu being displayed. A balance needs to be made between the number of options on a screen at one time and the number of levels of sub-menu required. Sub-menu options need to be logically link together.

A Menu-Driven interface can only deal with situations where the user’s requirements are known in advance as the user is limited to the predetermined choices that are built into the menus. A Menu-Driven interface is easy to use

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Menu-Driven Interface Advantages


  • Extremely easy to use. Someone who has never seen the interface before can work it out
  • There are no commands to learn or remember
  • Step-by-step options are given so that the user doesn't have to remember anything
  • Even if you don't know what to do, you can usually guess your way around the options
  • Menu interfaces don't have to be visual, they can be spoken - good for telephones or for visually impaired people
  • They don't need huge amounts of processing power or memory
  • It is fairly easy for the software programmer to create the same menus in different languages
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Menu-Driven Interfaces Disadvantages


  • A poorly designed menu interface may be slow to use
  • It can be irritating if there are too many menu screens to work through - users get annoyed or bored if it takes too long
  • You often can't go to the exact place you want right at the start. You have to work your way through the menu screens even if you know where you want to get to.
  • The menu can take up a large part of the screen so you have to keep flicking back and forwards between applications
  • If the menu is poorly designed it might be hard to read e.g. writing is too small for people with poor sight, colours might clash and be difficult to read, font style might be hard to read.
  • Too many sub menus will make it complicated for the user.
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Graphical User Interface

A graphical user interface (GUI) uses high-resolution graphics, icons and pointers to make the operation of the computer as user-friendly as possible. The aim of the interface is to make its use intuitive for a user. The use of sound and video are also made use of in many GUIs. Options can be chosen easily with a pointing device-usually a mouse. A GUI is sometimes called a WIMP environment as it uses:

  • Windows
  • Icons
  • Menus
  • Pointers

GUIs tend to need a lot more memory and disk space and take time to load because of the large number of graphical images used. The main operating systems used nowadays offer the users a graphical user interface. 

Many programs that run in Windows are known as WYSIWYG - this stands for What You See Is What You Get. In the early days of word-processors, you typed your essay or letter on the screen, but it could look completely different on the printer.

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  • Windows  - A window is a rectangular division of the screen that holds the activity of a program. There can be several windows on the screen at one time. The user can switch between windows and change the size and shape of the windows. The active window appears on top of the other windows. A dialogue box is a window that appears on the screen when information is wanted from the user. 
  • Icons - An icon is a small picture on the screen. Clicking on the icon performs an action such as saving a file. The same action can be performed using the menu system but the icon is used as a shortcut. The action performed when you click on an icon should be easily recognized from the image.
  • Menus - A pull-down menu is a menu that expands downwards when selected with a mouse or other pointer, the user then scrolls through the options and clicks to make a selection. A pop-up menu expands upwards when clicked on with the pointing device. 
  • Pointers - A mouse is a very common pointing device. It can move a cursor around the screen to be used for selecting a choice from a menu or pointing at any place on the screen. A tracker ball may be used in a similar way, however there are other pointing devices associated with GUIs. A laptop computer usually has a built in touchpad; a PDA has a stylus. If a computer is to be used by members of the public, a mouse may not be robust enough. In this case a touch screen is often used. 
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Graphical User Interface 2


  • This type of user interface is easy to use, especially for a beginner
  • It is easy to explore and find your way around the system using a WIMP/ GUI interface
  • You do not have to learn complicated commands
  • There are usually a reasonable 'help' system included with WIMP interfaces
  • You get the benefits of WYSIWYG
  • They let you exchange data between different software applications


  • GUIs take up a much larger amount of hard disk space than other interfaces
  • They need significantly more memory (RAM) to run than other interface types
  • They use more processing power than other types of interface
  • They can be slow for experienced programmers to use. These people often find CLI interfaces much faster to use
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Form-Driven Interface

This is a method of enabling you to interact with an application.The form normally provides limited choices as to the use.Form-Driven Interfaces are widely used to enter data into a computer system. Forms are used to capture a standard set of data items. 

Form-Driven Interface reduce the chances of an error because the user is prompted to fill in each field in turn. Forms can be designed so that if an essential field has been left blank, the form is not accepted until this field has been filled in. 

It is a good idea for an Form-Driven Interface to mimic the style of a paper form, so that it is intuitive for an inexperienced user to fill in. Form-Driven Interface should also enable the user to go back to make changes. 

Form-Driven Interface can include check boxes for yes/no answers and can allow the user to choose from a menu or a list.  This has serval advantages; it restricts the user to allowable options, reduces the possibility of error and is usually faster. Choices can be made from a menu using a drop-down box or by using options buttons. 

Another way of speeding up data entry is to use default setting the most likely entry is provided and it can be accepted by pressing a key to move the cursor to the next field on the form. 

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Form-Driven Interface 2


  • Intuitive to use (user friendly)
  • Looks similar to a questionnaire form
  • Select things using buttons and drop downs for data entry
  • Easy to program
  • Data validation can be used on data entry forms
  • Fast to enter data or to make choices
  • Little or no training required
  • They don't need huge amounts of processing power or memory


  • Uses more memory and disc space then a menu and CLI but less then a GUI or a voice control system
  • Only limited options presented
  • Visually impaired people might have trouble seeing the text or options
  • Not good for highly complex applications
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Dialogue Interface

This is a way of interacting with your environment by means of the spoken word.

For example many modern cars have a dialogue interface to allow control of the radio and mobile phone whilst driving. The driver simply says a certain command word such as 'Radio 2' whilst the car is in 'listening mode'. The computer controlling the interface will make sense of the command and take action, switching the radio to radio 2.

In order for these interfaces to work effectively they need to be 'trained' with the user. This involves the user speaking the commands until the system accepts the command and reacts appropriately.

Once training is complete the system becomes quite reliable in understanding the user commands. However, noise in the background can be a problem and may interfere with the interface understanding the command.

Dialogue interfaces often have a limited vocabulary.

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Dialogue Interface 2


  • Allows hands free control - useful to ensure safety when driving for example.
  • Useful for physically disabled users


  • Only limited uses
  • Expensive to develop
  • Training session with user required
  • May not operate reliably if there is background noise or user has a cold.
  • Not suitable for safety critical commands such as 'stop'
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Natural Language Interface

This type of interface allows the user to speak or type in their normal everyday language in order to interact with the computer.

For example, some applications such as speech recognition software accepts the spoken words and converts them into text on the computer. These applications have a much wider vocabulary than the dialogue interface.

An example of a natural language interface which makes use of written text is a 'chat bot'. This software mimics a conversation - you ask it questions and it will come back with a suitable comment for you.

This is the most technically challenging form of interface for the designers as it has to cope with different accents, dialects, slang, homonyms etc.


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Natural Language Interface 2


  • The user does not need to be trained in how to use the interface
  • More flexibility than a dialogue interface
  • Suitable for physically handicapped people


  • Reliability remains an issue - the interface can only respond to commands that have been programmed
  • Highly complex to program and so only warrants this kind of interface where other types of interface are unsuitable
  • Not widely available as other forms of interface are often superior
  • A voice interface might need training in order to get the software to recognise what the user is saying
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Touch Sensitive Interface

Touch sensitive interfaces can be found on many mobile devices such as a smart phone or a tablet computer.

They work by your finger touching the screen. The touching is detected and translated by the device into instructions. As well as tapping, the screen can sense swiping and pinching actions.

Many ATMs have touch sensitive screens where you can use your finger to select a service such as withdrawing cash or seeing your balance.

Ticket ordering systems in train and bus stations also use touch sensitive interfaces. You select your journey from a menu of options, select the date and time and then indicate how you are going to pay for the ticket.

Museums and art galleries often have touch sensitive screens where you can find out more information about a particular display or piece of art by selecting a graphic icon.

Updated operating systems such as Windows 8 now have built-in touch capability.

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Touch Sensitive Interface 2


  • Intuitive to use
  • You can see all of the options available
  • Do not need good ICT skills such as typing to be able to use
  • Most touch screens are fixed to a larger device so there is less chance of them being removed, lost or stolen (unlike keyboards)
  • Can be adapted for many uses e.g. cashpoint machine, shop, ticket sales office, garage


  • Need to understand the language or the meaning of the icons
  • Only limited options can be offered
  • If the screen becomes damaged it might not pick up the touch command
  • The screen could become scratched or dirty so it is difficult to see the options available
  • No so good in bright sunshine as the screen is hard to see
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