Chapter 2

Chapter 2

Differences in hardware and software
1. Hardware: things you can you touch
2. Software: programming code that makes the computer work
  1. System software: control the workings of the computer
  2. application software (word-processing programs, spreadsheets etc
Lack of Standardisation
1. Increased COST for parts and upgrades
2. Limited AVAILABILITY of hardware which will effect the cost
3. Limited and expensive TECHNICAL SUPPORT
4. Causes difficulties and expenses for TAKEOVERS
  1. incompatible computer systems
    1. having to purchase new equipment
    2. staff needing new training
    3. no communication between systems
Input, output and storage devices
1. Input devices
  1. Keyboard
    1. + good for inputting small quantities of data
    2. Concept keyboard: allows you to create you own keys
  2. Mouse
    1. Pointing device used to select items on a screen
    2. - needs some surface area to operate
  3. Scanner
    1. Translates information into a form the computer can use
    2. + lots of different types (bar code/OMR/magnetic card reader etc)
  4. Graphic tablet
    1. can manipulate images on screen/create free-hand drawings
  5. Digitiser
    1. converts analogue to digital data
2. Output devices
  1. Monitor
    1. takes signals on a computer and displays them on a screen
  2. Printer
    1. Produce a hard copy output
    2. + lots of different types (dot matrix/inkjet/laser)
  3. Plotter
    1. produces printouts using vector or coordinate graphics
    2. Flat-bed: stays still and pen moves
    3. Drum plotter
3. Storage devices
  1. Hard disks
    1. + portable hard disks allow large amounts of data to be transferred easily
  2. Optical disks
    1. CD-ROM
      1. available in fixed or forms which can be rewritten
      2. around 700mb
    2. DVD
      1. around 4.7gb
  3. tape drive
    1. large storage capacity
  4. Memory sticks
Specialist hardware devices
1. Visually impaired
  1. braille keyboard
  2. microphone
  3. loudspeaker
  4. braille printer
2. Motor imapired
  1. mouth-stick
    1. a stick to control input with the mouth
  2. puff-suck switch
    1. a tube placed in the mouth and blown/sucked through
  3. tongue-activated joystick
  4. eye-typer
    1. fits onto the muscles around the eye and when the eye is moved a pointer on the screen moves
  5. foot mouse
Specialist software
1. screen reader
  1. program that reads out a computer display
2. text-to-speech system
  1. takes written text and outputs is using a speech synthesiser
3. speech-to-text system
  1. takes spoken words and inputs them into the computer
4. Auditory feedback system
  1. plays sounds in response to user activity
5. screen magnifier
  1. zooms in on portions of the screen
6. predictive text
  1. suggests the required word
7. sticky keys
Different types of software
1. Operating system
  1. controls the allocation and use of hardware resources
2. User interface
  1. means by which the user can interact with an application
  2. menu: on-screen list of options
  3. form: on-screen form to enter data
  4. command line: space to type instructions
  5. natural language: a voice-based interface
3. Utility
  1. assists in monitoring and maintaining a computer system
  2. e.g. virus checkers/printer monitoring software
4. Application software
  1. allows the computer to be used to perform particular tasks for the end user
  2. e.g. word processors/spreadsheets
Characteristics of different user interfaces
1. Command-based
  1. user types instructions at a command prompt to control what the computer does
  2. - need good knowledge of the commands and the effects
2. Forms
  1. limited area on screen with boxes to fill in
3. Menus
  1. series of related items that can be selected
4. Natural Language
  1. allow the users to use their own language to communicate with the computer
  2. spoken interface: typified by voice recognition software

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