Usage of Event-driven Programming

There are environmental uses of event driven programs for non-graphical applications. One example would be air conditioning systems. These are suitable for event driven programs because you would want to turn the air conditioning on if it’s too hot or turn it off when it is too cold. When you press the button, it will trigger a heater which is on the inside and it will go off when it gets to the temperature that is shown on the dial. This is event driven because when you select the temperature on the dial and press the button, it will allow the air to flow through.

Most computers use event driven programs for non-graphical applications. A good example would be when you turn the power on. You don't even have to have the monitor turned on to have events occurring. When you press the button, there will be either one or two lights come on. The reason it does this is the fact that it shows the user that power is getting through the power supply unit and getting to the rest of the components in the computer. Also during this step you will be able to hear that power is getting through because you should be able to hear the fan start spinning.

Another good example of this would be opening the CD or DVD drive. This is a non-graphical application because you don't actually see anything happening on the screen. There are actually many events which occur whilst opening the disk drive. The first one is when you press the button, if there is a disk holder in the drive which is holding a disk, it will slow the disk down to probably about 25% of the speed. The reason it does this is because it will be spinning at an incredible rate because the laser needs to read it and if you try touching it at the speed it is spinning at, you will most likely cut your hand. The next event in this process is the light which appears either just at the side of the disk drive or just below it. You will notice that the light will star flashing when you press the button. This happens when you open the disk drive because it will alert you to whether the disk drive is opening. You can then put your disk in and close the tray again.

The next event that occurs is the fact that the fan inside the computer will start spinning at an even faster speed. You don’t necessarily see this but you will hear it. The reason this happens is because the laser which is used to read the disk will get very hot and the fan was only keeping everything else cool so it will have to go even faster if the laser is in use as well.

Another example could be in the MS DOS operating systems. It doesn’t make use of wimp when it’s interacting with the user. The user uses/enters computer commands into the computer to give instructions such as saving files, opening new documents other than using a mouse to do this action. A keyboard is used to enter this command and “keydown” events occur when this happens.

There is a large number of mobile devices which can range from mobile phones to tablets to laptops. Mobile phones use non graphical applications. Most phones now are touch screen and there tends to be widgets on the main screen to get to things, so I am going to have to talk about older phones. When you are navigating through the menus on an old Nokia you have to press the main button on the keypad which will bring you to the menu. You will then have to press the keypad in the particular directions to get to the icon and then press the menu button again to get onto the separate menus. You then have to type your text and select the contact you want to send it to. You then click send and it will go to the other phone. All of the steps in this are event driven and are all click events. They are suitable because there wouldn't be any other ways of doing it.