The human-computer interface

The human-computer interface

1. Interfaces

   • The human-computer interface is a boundary where the user and computer meet.
   • Its normally referred to as user interface and it determines the way that the user with the computer also gives instructions about what is wanted.
   • A users design interface for a piece of software takes into account that only expected ICT skills of users. companies design interfaces to make the programme easier to workers.

2. On-screen help

   • Many interfaces provide assistance in the form of on-screen help.
   • Most software has ways that help can be asked for. Sometimes this is generalised help or sometimes it is known as context-related help as it gives you help about the part of the software you are using at the moment.
   • 0lder versions of Microsoft office, there was an Office Assistant which came up to give context-sensitive help. After a bit this could become annoying and it was normally turned off.

3. Command-line interface

   • The prompt character is the users type in a command. This system then executes the command, therefore telling a computer what to do which was used in early days of computing.
   • some commands might have switches which will give options for the command you have chose. E.g. in Microsoft operating systems, one is the command for listing the files in a folder called 'DOCS' on the drive C is DIR C;/DOCS.
   • A switch \W means that the filenames are to be printed across the screen instead of down and the instruction that needs to be entered at the command prompt is called DIR C:\DOCS /W
   • Many instructions have a number of switch's and that means the command can become very complex
   • Advantages
     • Instructions execute quickly. Instructions are versatile - meaning the user can select a large number of options for each instruction. The operating system s smaller when loaded into memory.
     • Disadvantages
       • You need to learn the special instructions used. If you mistype an instruction or spell it wrong, then it cannot be executed. Some commands and their options can be very complex, so high-level ICT skills are needed.

4. Graphical user interface

   • Modern computer operating systems use a graphical user interface (GUI). Which is small meaningful pictures also known as icons represent instructions that are available to the user, and each one is selected by using a mouse pointer.
   • Modern operating systems use WIMP environments; Window, Icon, Menu, Pointer
   • Most GUIs provide help if users have difficulty. The purpose of a command button is often displayed if the mouse pointer hovers over it and a help menu provided a searchable database that explains how to perform various tasks. Sometimes the help provided is a link to a website.
   • Most GUIs provide help if users have difficulty. The meaning of a command button is often shown if the mouse pointer hovers over it and a help menu provided a searchable database that explains how to perform various tasks. Sometimes the help provided is a link to a website.
   • Advantages
     • Only a low level of ICT skills is needed for the easy-to-use, intuitive interface.
     • There is no need to learn any instructions.
     • Pictures are more meaningful than words, so small children or people with reading problems can use this sort of interface.
     • You can alter the way in which a GUI displays data to suit your own circumstances.
   • Disadvantages
     • It is large and complex. It can take up a lot of a computer’s resources and may run slowly.

5. Menu driven interface

   • A list of options allowed to the user is showed and the user then can selects one of them, usually by clicking the mouse button with a mouse pointer on the option you need or by pressing a key on the keyboard.
   • Lots of menus can be available to the user and they are usually organised into groups of other options. Selecting one option may open another menu item.
   • Some sub-menus can then also have further sub-menus too.
   • Advantages
     • Navigation to find the option required is simple. You do not need to learn what instructions are available as they are displayed in the menu. User input is validated as only the options shown can be used
   • Disadvantages
     • Navigation to find the option required is simple. You do not need to learn what instructions are available as they are displayed in the menu. User input is validated as only the options shown can be used

6. Main types of user interfaces

   • Command-line interface- users type instructions using special set of words and symbols, this was usually early days of computing
   • Menu-driven interface - a menu of options is displayed and the user select one of them. Which Is more user friendly then the command line.
   • Graphical user interface (GUI)- Small pictures are used to represent options that the user can select.
   • Voice interface- A microphone is used which the user speaks to command (operate) the computer (sophisticated software).
   • Special devices- for example braille keyboards 'concept keyboards' which has overlay places on the keyboards. It has touch-sensitive screens , puff-suck switch's allow input for people with no arm movement.

7. Touch-sensitive interface

   • Some devices work by a user touching them. Touch screens are often used in places where devices such as a mouse or keyboard may get stolen or damaged. E.g. Ipad
   • Touch screens are often situated in places where members of the public can use them e.g. doctors’ surgeries, banks etc.
   • Advantages
     • Only a low level of ICT skills is needed to use it.
     • There is little possibility of damage or theft.
     • They can be used in environments where gloves are necessary and so a keyboard cannot easily be used.
   • Disagvantages
     • The disadvantages of a touch screen is that it may become dirty or scratched and difficult to read.

8. Point-of-sale interface

   • In supermarket of other large store are usually linked to a computer that monitors the sale of items.
   • The data uses input using a barcode reader or a keyboard. Items and prices are shown on a small monitor and a receipt is printed.

9. Biometric systems

   • Biometric systems use physical characteristics such as fingerprints, voice, facial features and eye scans to identify people.