Computer Science A Level Manual Input devices

Computer Science A Level Manual Input devices

1. Keyboards

   • Standard Keyboards
     • Most computers have QWERTY keyboards. These can be used to enter in data manually. A lot of work has been done to ensure that keyboards are designed ergonomically. There is a health and safety problem known as Repetitive Strain Injury (RSI) for people who use keyboards all the time.
   • Touch Sensitive Keyboards
     • They have 'keys' which are made up of touch-sensitive areas on a plastic cover. A user presses on the touch-sensitive area to input data into the computer. They can be used in fast food restaurants. Operators simply press on pictures on the keyboard. This speeds up data input and means that training needs are minimal. Dirt can get into normal QWERTY keyboards and cause them to malfunction but the protective plastic cover on touch-sensitive keyboards stops this happening.

2. Screens

   • Touch Screens
     • A user makes a selection by touching the screen with their finger. Touch screens allow very fast selections from choices. They could be used in places where people need to find out information but may have zero computer skills, for example, an information system in a library or a museum. They would be of limited use if you had to type in a letter, for example.
   • Graphic Tablets
     • These are touch-sensitive pads that allow you to 'draw' on them with a stylus. The pressure from the stylus on the pad is sent to the computer, which reproduces what was done on the pad in a drawing program or Computer Aided Design (CAD) program. These types of data input devices are far more natural for designers to use than trying to use a keyboard and mouse to draw with.
   • Visual Display Units
     • Monitors are ideal for displaying data and information to users. They come in a range of sizes. Larger ones such as 21-inch screens, for example, would be ideal for engineers using Computer Aided Design software applications. 15-inch screens are perfectly acceptable for users using a range of generic applications. Old CRT (Cathode Ray Tube) monitors take up a lot of space on a desk. Flat panel liquid crystal display screens, often referred to as TFT screens, save a lot of space by comparison. They are not quite as sharp as CRT screens, however, and are more expensive. TFT screens produce less radiation than CRT monitors. Excessive exposure to radiation is seen as a potential risk to computer users. TFT screens use about half the power a CRT screen uses.
   • LCD (Liquid Crystal Display) Monitors
     • These contain groups of red, green and blue diodes to form each pixel. The screen is typically back-lit using LEDs (Light Emitting Diodes). The advantages of LCDs: They reach max brightness almost immediately. Sharper image with realistic and vivid colours. Brighter light Thinner in construction. Last a long time meaning they are reliable. Consume very little power
   • Organic LED (OLED) screens
     • These are thinner, brighter and lighter than LCD or LED screens. The screen is plastic rather than glass and is flexible. In the future these may be used for pages in electronic books or magazines, paintings on walls or even in clothes. The advantages of Organic LED (OLED) screens:
       • The advantages of Organic LED (OLED) screens:
         • Made of plastic rather than glass so flexible Thinner than LCD/LED Bright without the need for backlighting Consume less power which is good for portable devices (eg smartphones) Fast refresh rate (good for video games) Greater depth of colours Better viewing angles

3. Cameras and Camcorders

   • Digital Cameras
     • Images are stored digitally. The images are then transferred to a computer. The amount of memory is a very important consideration with these cameras, as is the ability to add memory using a memory card. This is because storing images is storage intensive. Cameras often allow the user to select between high resolution and low resolution modes. If you use a high resolution mode, you will be able to take fewer pictures than low resolution mode. You can immediately view photos and re-take or overwrite them if they are not what you want.
   • Camcorders
     • Video camera recorders, or camcorders, are cameras that store moving images. Some camcorders store the moving images as analogue signals. Analogue camcorder films lack really mint quality and lose quality if they are copied. Films made using digital camcorders, have much better quality and don't lose any quality if they are reproduced. This is because the films are stored digitally. Digital Video (DV) is a common digital format.