The human-computer interface

The human-computer interface

1. GUI (WIMP)

   • WIMP stands for
     • Windows- A rectangular area on the screen where the commonly used applications run
     • Icons - a picture or symbol which is used to represent a software application or hardware device
     • Menus - a list of options from which the user can choose what they require
     • Pointers - a symbol such as an arrow which moves around the screen as you move your mouse. Helps you to select objects.
   • Advantages of GUI (WIMP)
     • 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 good help facilities provided with WIMP interfaces
     • You get the benefits of WYSIWYG
     • They let you exchange data between different software applications
   • Disadvantages of GUI (WIMP)
     • Can be much slower because 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 faster to use

2. Command-line interface

   • Disadvantages
     • 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
   • Advantages
     • If the user knows the correct commands then this type of interface can be much faster than other types of interface
     • This type of interface needs much less memory (RAM) in order to use it than other 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

3. menue driven interface

   • Advantages
     • Extremely easy to use. Someone who has never seen the interface before can work out what to do
     • 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 round 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
   • 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

4. speach and sound

   • Advantages
     • 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
   • Disadvantages
     • 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
     • A voice interface might need training in order to get the software to recognise what the user is saying

5. Touch sensitive interface

   • Advantages
     • Do not need good ICT skills such as typing to be able to use
     • Less chance of theft (because of the touch password)
     • 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
   • Disadvantages
     • Can get dirty and scratched easily
     • Only limited options can be offered
     • No so good in bright sunshine as the screen is hard to see