1. E.g.: MS-DOS interface. DIR C: /W /A:D will list all the directories in the root directory of drive C in wide list format. Disadvantage is that commands need to be known, typed and spelled correctly. Advantages - versatile as a number of different 'switches' can be used to moderate the command. There are many different ways in which humans communicate with computers: Text based (command line) With this type of interface, the user types in commands: Human - Computer Interface

2. Advantages  The user does not have to learn commands.  Easy-to-use method  Avoids ambiguous or invalid data being entered - most drop-down boxes only allow the options listed to be selected. Free format dialogue Text can be entered in a special form. This is used by some 'Help' programs and some search engines on the Internet. Example : How do I ………… Dialogue boxes (Forms) An on-screen form is displayed and the user has to enter data and select options using text boxes, radio buttons, drop-down boxes etc..

3. GUI (Graphical User Interface) Uses windows, icons and menus representing options which can be selected using a (mouse) pointer. Advantages  Intuitive  user-friendly'.  Suitable for users with lower IT skills.  A number of different applications will use the same icons and methods - so each one 'feels' the same.  Run many programs in different windows  Copy and paste easy  Consistent across world Problems Can take large amounts of processing power – though less of a problem these days. Slow to load and run Can take many clicks (menus) to get to a simple instruction Dedicated keys Some keys or combinations of keys may perform pre-defined tasks  E.g. and may save a piece of work.  and may re-boot a computer.

4. Soft keys It may be possible to program keys to perform tasks when pressed.. Some keyboards may have programmable 'function' keys. Pointing devices Manipulating a device which moves a pointer on the screen. Examples :  Mouse  Tracker ball  Joystick  Graphics Pad Light Pen/Puck

5. Speech recognition Microphone used to receive speech input. Speakers used for speech output. Advantages Hands are free to do other tasks Disabled people can interact with the computer Speed of data entry Problems: Users may speak different languages; Local accents may not be recognised; Some words sound the same - two, to, too Time to train to your own voice Handwriting Some hand-held computers allow users to 'write' on the screen. Advantages No need to re enter data that is written No need to learn to type Flexible – no need to carry laptop Can make notes – whiteboard. This is useful in teaching Problems: Complex software needed to recognise different people's handwriting. Many different ways to form letters Need to train A sense check would help

6. Design Validation After a new computer system has been designed, a check has to be made to ensure the new design is compatible with the original specifications of the system. A review of the design is undertaken to make sure that... the design corresponds with the specifications, and that the objectives of the new system are satisfied. the most appropriate techniques have been used, the user interface is appropriate. Failure to check at the design could mean  Errors made in the design stage will carry through to all further development of the new system. If there were mistakes made at the design stage, a lot of work would be done in implementing a system which, at worst, did not work, or at best, did not do the job well.

7. Evaluating a Design How would you decide whether a system design is a good one? Some criteria.... does the design achieve the objectives? is it possible to implement the design with the manpower and expertise available? is it technically feasible? Does all the hardware exist? is the design as simple as possible so people can easily understand how it works? Complex designs are harder to get working and harder to solve problems which arise. is it possible to implement it within the time-scale proposed? is it possible to implement the design within the budget available?