GLOSSARY

Indicates that data does not have to be viewed “in order”. Any piece of data can be accessed without having to seek through earlier data first. An example of this is a DVD or Blu-Ray. If you are watching a movie on DVD, you can select a scene from the menu and go directly to that scene.

Indicates that data cannot be accessed without having to look through all earlier data first, in order. This term is best illustrated by example. A video tape and a cassette tape are sequential access devices. If you want to access a part in the middle of the video tape, you need to fast forward through everything up until that point. You cannot go directly to the middle of the tape. If you want to start at the beginning of the tape, you need to rewind.

A device such as a printer, keyboard or an expansion card that connects to a computer. Peripherals add extra functionality, separate from the main functions of a computer.

A circuit board that can be connected to a computer motherboard in order to add functionality to a computer.

Stands for Human Machine Interface. It is another word for Panel PC. It is a term commonly used in factories because the Panel PC lets the user (human) interact with the machinery they are operating. Hence the term human machine interface.

A computer and a display built together in one unit. A Panel PC is made to stay in one place, whether it is built into a wall, a piece of machinery or a car. This is in contrast with a smartphone or a tablet computer which are made to be moved around.

OLED stands for Organic Light Emitting Diode. A diode is an electric conductor in which electricity can only flow in one direction. A light emitting diode is a diode that lights up when electricity is passed through it. OLED displays are made of millions of little LEDs. Each LED has one of 3 colours: red, green, or blue. An OLED display will apply electricity to the different LEDs to produce many different colors. By doing this with all of the millions of pixels, the display can produce pictures. OLED displays have a few advantages over LCD displays. Because OLED displays don’t require a backlight, they can be made much thinner. OLED displays also require less power and the pixels in an OLED can react quicker than those in an LCD. “Organic” in this term comes from chemistry and means that the LED is made of carbon-based materials.

Stands for Liquid Crystal Display. Liquid crystal is a type of liquid that has an arrangement of its molecules, similar to crystals. Because of this, it can refract (change the direction of) light in many different ways, similar to a crystal. Another interesting property, is that liquid crystal can change shape when electricity is applied to it.

The way that an LCD works, is that there is a backlight at the back of the display. In front of the backlight is the liquid crystal. In front of the liquid crystal are millions of tiny pixels (dots). Each pixel is composed of 3 parts, red, green and blue. These parts are called sub pixels. Under normal circumstances, the backlight shines through the liquid crystal and the liquid crystal sends light through all 3 colors at once, with equal intensity, and creates white light. But when electricity is applied to the Liquid Crystal, it changes shape and blocks part or all of the light that goes through to each of the sub pixels. If the liquid crystal blocks all of the light, the color is displayed as black. If the liquid crystal blocks only part of the light, different colours will be displayed, depending on how much light is blocked to each sub-pixel. By applying electricity differently to the liquid crystal behind all of the millions of pixels, the display is able to create pictures with a very wide range of colors.

LCD Video:

https://www.youtube.com/watch?v=0B79dGR19Tg

A device with a screen which receives data from a computer or other source and puts that data up on its screen in a graphical representation. It is used to show text, images, videos, etc.

A computer case.