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Chapter 2 Hardware. Parts of computer. Types of computer. (Micro-computer). Hardware . Input Devices Manual and Automatic. Manual . Keyboard Used to input data into the computer Advantage They are very common; all computers have one and they are easy to use. Disadvantage
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Keyboard • Used to input data into the computer • Advantage • They are very common; all computers have one and they are easy to use. • Disadvantage • Easy to make mistakes if you can’t type quickly. • Concept Keyboard • A pictorial keyboard which you can press. • Advantage • Easy to use and waterproof • Disadvantage • The screen can get dirty. • Might need to change the pictures if your stock changes
Mouse Enables you to control the movement of the on screen curser by moving it around a surface • Advantage • Easy to learn to use • Accurate for selecting things • Disadvantage • Need a flat space next to the computer. • Tracker Ball • Like an upside down mouse, you turn it with your hand to move the pointer on the screen • Advantage • Ideal for using when flat space next to computer is limited • Disadvantage • Not supplied as standard.
Joystick • Similar to a tracker ball in operation except you have a stick which is moved rather than a rolling ball. • Advantage • Immediate feel of direction. • Disadvantage • Some people find them more difficult to use than mice. • Microphone • Used to input sound • Advantages • Some systems can understand most peoples voices with voice recognition software • Disadvantages • Some systems need to be trained to understand each different voice.
Digital Camera • Looks very similar to a traditional camera. However, unlike photographic cameras, digital cameras do not use film • Advantage • No film needed. • Images can be digitally manipulated • Disadvantage • Need to print out photographs • Scanner • Another way in which we can capture still images or text to be stored and used on a computer. • Advantage • Can input things from paper documents • With OCR software, text can be scanned in • Disadvantage • Images can take up a lot of memory space.
Graphics tablet • Produces much more accurate drawings on the screen than a mouse or a pointing device could. • Advantage • Effective method of creating or changing diagrams and images. • Disadvantage • Only useful for inputting data about diagrams. • Can be very sensitive to movement and difficult to get used to using
MICR • Stands for Magnetic Ink Character Recognition. Banks use them; the reader reads the numbers on a cheque. • Advantage • Read at 100% accuracy.. • Disadvantage • The reader and ink is expensive • OMR Stands for Optical Mark Reader. Reads pencil marks on a specially designed form or document, e.g. on a lottery ticket. • Advantage • Fast and accurate way of inputting information. • Disadvantage • Only works if the marks have been made accurately and clearly.
OCR Stands for Optical Character Recognition. It enables the computer to identify written or printed characters which have been scanned in. • Advantage • 95% accurate • Disadvantage • Needs careful checking as letters can be misread. • Barcode Reader • A bar code reader uses a visible red light to scan and read the barcode. The reflected light is translated into digital data that is interpreted by the computer and the correct price and product information is displayed. • Advantage • Any price change only needs to be changed on the computer system, not on each item.
Magnetic Stripe Build into back of plastic cards, e.g. identity cards or credit cards. Holds information about the card owner. • Advantage • Simple to use and cheap to produce. • Disadvantage • Limited storage capacity – only 60 characters. Sensors Sensors are used to detect physical quantities outside a computer such as temperature, pressure and light. To be able to process input from sensors a device called an analogue to digital converter must be connected between the computer and the sensors. This device converts signals from sensors into digital data that the computer can process
Output • Once the computer has processed all the information from the inputs then it must display or output the information in some way. • This is when we use Output devices that enable us to see or hear the information stored in the computer.
Output Devices There are many different Output devices but the most commonly used are: • Monitors • Printers • Speakers / Headphones • Lights • Plotters
Monitors • Monitors display the information on a screen. • You can get 2 main types of monitors: CRT’s: Cathode Ray Tube monitors are fairly large and they are not as common as LCD’s nowadays. CRT’s work by using an electron gun situated at the end of the tube. LCD’s: Liquid Crystal Display monitors are thin and are more commonly used. They work by using electronically charged crystals.
Printers • There are 3 types of Printers: Dot Matrix : This printer is the oldest of the three and is not used much now because it doesn’t give as good results as the other two. It uses Carbon ribbon and pins. Ink Jets : This printer has become cheaper and is commonly used at home as they are perfect for small quantities of work. The ink jets use ink cartridges that are heated up and droplets are then dropped on to the paper forming a small part of the overall image. Laser : This printer is more expensive that the others however it is excellent for use in work as it is quiet, quick, can be stocked with a lot of paper and produces high-quality work.
Plotters • These devices produce high quality lines diagrams on paper. Architects, Engineers and Scientist often use plotters. • The plotter uses a pen that can be lifted on and off the paper which is how this dev
Speakers / Headphones • There is usually a small speaker within the computer however to increase the volume and quality of the sound we plug in external speakers which allow us to hear the music better. • Headphones can be plugged into almost all computers and they enable you to listen to your music without disturbing others.
Lights • These are known as LED’s (light emitting diodes) and they are useful in presentations and also for situations like when a computer is controlling traffic lights. • LED’s last approx. 100,000 hours and they can either be dim or very bright.
