The Human-Computer Interface

The Human-Computer Interface

1. GUI (WIMP)

   • Advantages
     • 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
   • Disadvantages
     • 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
   • Command Line Interface
     • Advantages
       • 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
     • 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
       • You can't just guess what the instruction might be and you can't just 'have a go'.

2. Menu 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 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
   • 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.
   • Speech & 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
       • Not widely available

3. Touch Sensitive

   • Advantages
     • Instinctive
     • You can see all of the options available
     • Do not need good ICT stkills 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 where other interfaces may be inappropriate e.g. cashpoint machine, shop, ticket sales office, garage
   • Disadvantages
     • Need to understand language and what symbols mean
     • 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

4. Biometrics

   • Fingerprints
   • Voice recognition
   • Retina scanner
   • Facial features
   • Palm pront