AS - Input Devices

AS - Input Devices

1. Examples

   • Scanners
     • Input an image into a computer. Images are stored as a JPEG file or BMP. The accuracy of the output produced by the software is dependent on the image qualityof the original image.
   • Digital Cameras
     • Can connect to a computer via a USB port or memory card being inserted into a card reader and then inputted into a computer. Images can be downloaded and stored. Some digital cameras can capture moving images and sounds. These can be stored in a format suitable to be loaded onto a PC.
   • Touchpads
     • Touch sensitive and allows the user to move the cursor with their finger around the pad. Not as easy to use as a standard mouse.
   • Graphics Tablets
     • Bespoke hardware used to input drawings made using a stylus and moving on the pad. The drawings are automatically uploaded to the computer. Very accurate images can be produced and are ideal for graphics designers, artists and technical illustrators.
   • Keyboard
     • Ergonomic keyboards are available and are designed to reduce the risk of repetitive strain injuries (RSI). Concept keyboards are designed for a specific purpose. E.g. food businesses use these with a grid of images which can be selected to represent a menu item.
   • Touch Screens
     • Make selections by touching the screen. Both input and output device. When an icon is selected, it is opened and reveals more information which is then displayed. A touch screen can provide a robust device that is very simple to use.
   • Optical Character Recognition (OCR)
     • Method of data capture where the device recognises characters by light-sensing methods. Characters entered are usually typed or computer printed, even hand written. Used to input large volumes of data. OCR is common using a flatbed scanner connected to a computer. Uses a two step process; 1. A page of text is scanned and the data is encoded as a graphical image. 2. The OCR software scans the image using pattern-recognition software where dots are matched against stored templates.
   • Optical Mark Recognition (OMR)
     • A form of mark sensing where pre-printed documents are used. These contain boxes where marks can be made to indicate choice. The device detects the written marks on the documents by shining a light and recording the amount of light detected.
   • Magnetic Ink Character Recognition (MICR)
     • Fast a reliable method of entering data. Documents are pre-printed with character data in special ink that can be magnetised. The shape of the characters is recognised by detecting the magnetisation of the ink. Used to read cheques. Used in situations when security is important.
   • Barcode Readers
     • Used for the identification of items where items have their own unique code. Used in a supermarket and their products. The codes are read from the stripes by detecting patterns of reflecting light and encoded into computer readable form using a form of scanner. Barcode readers can be hand held, either moved over the barcode or fixed where the item is moved over the reader.
   • Magnetic Strips
     • A strip of magnetic material in which encoded information stored can be automatically read into a computer as it is read by a reader. The pattern of magnetisation is detected and converted into binary code.
   • Radio Frequency Identification (RFID)
     • Tags that emit radio signals. Different tags emit different signals. Fast method of identification.
   • Speech Recognition
     • Reliable speech recognition is cheaper. Used in mobile phones as users can speak using this to perform an action. Enables large quantities of text data to be inputted as words into the computer. Can be used to input simple control instructions to manipulate data or control software. Allows users who have limited ability to type, due to RSI or disability to interact with the computer system.
     • Advantages/Disadvantages
       • Advantages= Can achieve faster data entry than typing, the user's hands are free for other purposes, allows people with disabilities to interact with the system, useful if the keyboard is impractical
       • Disadvantages = Must speak each word with clear gaps in between. Does not understand natural speech, needs to be trained to recognise a voice, excessive background noise can interfere with the interaction, may only be able to recognise a small number of words.

2. Influential Factors

   • Volume of Data
     • If the volume of data is large, the automatic equipment is appropriate. Manual data entry such as a keyboard would not be able to cope with the reasonable time.
   • Speed
     • Important for data entry. Automated data entry methods, such as OCR and OMR, can produce very fast data entry.
   • Nature of System
     • A particular system may have a specialised input method associated with it. Determined by the environment that the device is used in.
   • Ease of Use
     • The conditions under which data is to be entered, together with the range of skills of the users, may influence the choice of data capture method.
   • Technological Development
     • The choice of data entry method for a particular system may have been different years ago and may be different again in years to come. New methods are being developed all the time. It is important that methods are reliable and have confide3nce of the users.
   • Cost
     • The cost of installing a particular input method is a major factor. Cost could relate to staffing or hardware, as well as changing from system to new. The greater volume of data will be likely to cost more.