COMPUTER INTERFACES

The term interface means the link between the computer and the user; it refers to the means by which the user interacts with the machine. 2 2

What we see when we look at the computer is a part of the interface What we use to give commands to the computer is also a part of the interface 3 3

This means therefore that the interface is both hardware and software. 4 4

HARDWARE Hardware comprises all the parts of a computer system you can see and touch but not every item of hardware is a part of the interface. All input and output devices form part of the interface as they are the means by which the user gives and gets information to and from the computer. 5

In addition to the run of the mill input and output devices, the following are of special note : Touch screens Sensors Braille Keyboard Non visual interfaces

TOUCH SCREEN What is A Touch Screen? A screen which acts as both an input and output device by allowing the user to interact with the computer by using his/her finger or a stylus to give commands or make selections by touching the screen. Example of A Touch Screen

SENSORS What is a Sensor? A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. Many computerised industrial systems use sensors to pick up input data which is then transmitted to the main computer system for processing.

Sensors can detect changes in pressure, temperature, speed, etc The use of sensors means that no human input or interference is required 9

What is A Braille Keyboard? Keyboard marked with raised dots for the visually impaired. BRAILLE KEYBOARDS Example of A Braille Keyboard

NON VISUAL INTERFACES A Non Visual Interface is a type of interface that allows the user to interact with the computer without seeing it Two important non visual interfaces are audio input to a microphone and output from a speaker,

SOFTWARE INTERFACES 12 12

SOFTWARES Software is the name for all the programs that computers use to perform different tasks. How the software looks and how one interacts with it, is the software interface

There are three major types of software interfaces : Command driven interfaces Menu driven interfaces Graphical user interfaces 14

COMMAND DRIVEN INTERFACES

COMMAND DRIVEN INTERFACES A Command Line or command driven interface presents the user with a prompt on a blank screen and requires the user to interact with the computer system by typing in commands. Any command which is entered must be typed in the correct syntax to in order to perform the required operation. 16

COMMAND DRIVEN INTERFACES 17

COMMAND DRIVEN INTERFACES Examples of programs which use a Command Driven Interface are: Dos, Linux and Unix. (Note that these are all operating systems) 18

This is an example of a DOS window This is an example of a DOS window. The screen simply waits for the user to type a command. 19

COMMAND DRIVEN INTERFACES To interact with a a command driven interface the most important piece of hardware we require is a keyboard. We also tend to need the monitor for output. 20

ADVANTAGES of COMMAND DRIVEN INTERFACES Faster than using other interfaces Uses less memory because there are no graphics Works on computers with limited hardware and software resources Experienced users can use this system faster than others. Complex commands can be entered to customise the system for a particular user.

DISADVANTAGES of COMMAND DRIVEN INTERFACES People with limited knowledge of the commands find the interface confusing and hard to use. Errors in commands can cause the operation to fail and can be very time consuming. Any errors in typing will require the user to re-type the command. This is time consuming and frustrating. Commands have to be learnt and this is difficult especially when there are hundreds of them The interface is not attractive compared to a GUI interface.

MENU DRIVEN INTERFACES 23

MENU DRIVEN INTERFACES A Menu-Driven program is one that presents users with a list of choices and available options. Menu–Driven programs are usually considered ‘friendlier’ and easier to learn than programs with a command–line interface.

MENU DRIVE Menu -Driven is a program that uses menus to present choices of command and available options. Menu –Driven programs are usually considered ‘friendlier’ and easier to learn than programs with command –line interface. 25

Example of Menu- driven interface 26

ADVANTAGES Free from typing errors, because user does not have to type commands. Easier to learn than a command driven interface

DISADVANTAGES Several steps required to issue a command. Once user has learned the menu system it is bothersome to have to wait on the package to present the questions before command can be entered. Limited use of colours

GRAPHICAL USER INTERFACES 29

GRAPHICAL USER INTERFACES A graphical user interface is a type of user interface which allows people to interact with electronic devices such as computers, hand-held devices, gaming devices, household appliances and office equipment with images rather than text commands. The main interfacing device for a GUI is the mouse.

GRAPHICAL USER INTERFACES A graphical user interface is sometimes regarded as a WIMP interface. It has Windows Icons Mouse usage and uses a Pointer 31

Advantages of GUI Easier to learn and use; user friendliness Icons/symbols are easier to recognize and provide the user with a context Fewer command error Reduce typing

Disadvantages of GUI May consume more screen space For programmers the design of Graphical User Interface is more complex Increased use of computer memory can lead to slower processing Takes up more disk space. Takes up more memory

SOFTWARES The GUI is more appropriate for children and also for inexperienced computer users. Programmers and other highly technical professionals prefer the command driven interface 34

Miscellaneous In addition to knowing the interfaces there are some other terms we should know. 35

ICON A computer icon is a graphical symbol that represents a property, function, or entity. In computer applications, icons are used to quickly execute commands or open programs and documents. You access the functionality behind an icon by clicking or double-clicking it. Examples of Icons

PULL DOWN MENUS Also called a drop down menu A menu of commands or options that appears when you select an item with a mouse The item you select is generally at the top of the display screen and the menu appears just below it as if you had pulled it down Example of Pull-Down Menu

POP -UP MENUS What is A Pop –Up Menu? A menu that is not visible until accessed. When accessed, this menu will open a new window and commonly be above all other screens on the display. Often used in dialog boxes to provide a list of mutually exclusive choices; a more compact choice than listing the items as radio buttons. Examples of Pop –Up Menus

An interface has both hardware and software elements Types of software interfaces include the Command Driven interface, the Graphical User Interface and the Menu Driven interface Specialised hardware interfaces consist of Touch Screens, Sensors, Non-Visual Interfaces and Braille Keyboards.

THE END Done By: (Group 3) Shaneka Earl Edwina Henry Daneile Matheson Brittany Clarke