COMPUTER HARDWARE AND SOFTWARE

• Software


  Programs that tell the hardware of a computer what to do
• Categories of software


  • System software
  • Application software
• System software


  • Programs that control the operations of the computer and its devices
  • Serves as the interface between the user, the application software and the computer's hardware
• Types of system software


  • Operating system
  • Utility programs
• Operating system


  Set of programs that coordinate all the activities among computer hardware devices
• Utility programs


  Allows a user to perform maintenance-type tasks, usually related to managing a computer, its devices, or its programs
• Functions of operating systems


  • Starting the computer (booting)
  • Managing programs
  • Managing memory
  • Utility services
  • Monitoring performance
  • Controlling a network
  • Administering security
  • Allowing user interaction
• Application software


  Programs that are designed for the end user
• Software package


  A program or a set of programs together with a full set of documentation/manual
• Uses of application software


  • Word processing
  • Spreadsheet
  • Database
  • Presentation graphics
  • Accounting
  • Desktop publishing
  • Computer aided design
  • Video and audio editing
  • Multimedia authoring
• Categories of software packages


  • Integrated software
  • General purpose software
  • Custom written (tailor made) software
• Integrated software


  Required features of a single application may not all be included
• General purpose software


  Commands are common throughout so it is easier to get used to, moving data from one program to another is easier, cheaper to purchase, take up less memory than separate applications
• Custom written (tailor made) software


  Software meets the need of the user specifically, can grow with a company, an experienced software team is needed, training is ongoing if people who were trained initially may resign
• Types of user interfaces


  • Menu driven
  • Graphical user interface
  • Command driven interface
• Menu driven


  Provides a list of commands to choose from
• Graphical user interface


  You interact with the software using visual images by selecting commands with the use of the mouse
• Command driven interface


  Interaction with software is made by typing commands at the prompt
• Hardware


  Computer components that we can see and touch
• Hardware components


  • Input devices
  • Processing unit
  • Output devices
  • Storage devices
• Control unit


  Monitors the operations of the computer system
• Arithmetic and logic unit

  Performs calculations, comparison and Boolean operations
• Immediate access store


  Holds all the programs and data during processing
• Input devices


  • Keyboard
  • Mouse
  • Microphone
  • Touch screen
  • Scanner
  • Graphics Tablets
  • Wheel
  • Joysticks
  • Light gun
  • Game pad
  • Optical Mark Reader (OMR)
  • Magnetic Ink Character Recognition (MICR)
  • Magnetic Stripe Reader
  • Optical Character Recognition (OCR)
  • Biometric Devices
  • Sensors
• Specialised input devices


  • Braille keyboard
  • Large key colour coded keyboard
• Output devices


  • Hard copy
  • Soft copy
• Hard copy output devices


  • Impact printers
  • Non-impact printers
• Impact printers


  Printer that works by banging a head or needle against an ink ribbon to make a mark on the paper, can be used on harsh conditions
• Non-impact printers


  Do not operate by striking a head against a ribbon, some spray ink while others use heat and pressure, produce output in a short period of time, used to print graphics and a wide variety of font
• Soft copy output devices


  • Monitors
  • Data projector
  • Speakers
  • Headsets
• Bit (Binary digit)


  Logical 0 or 1 representing a passive or an active state of a component in an electric circuit
• Nibble


  A group of 4 bits
• Byte


  A group of 8 bits, the smallest unit which can represent a data item or a character
• Word


  A group of fixed number of bits processed as a unit which varies from computer to computer but is fixed for each computer
• Types of memory


  • Primary storage
  • Secondary storage
• Primary storage


  Also known as main memory, faster than secondary memories, a computer cannot run without it, has limited capacity
• Subcategories of primary storage


  • RAM
  • ROM
• RAM


  Random Access Memory, working memory of the computer, usually volatile memory
• ROM


  Read Only Memory, non-volatile memory, stores permanent data and instructions
• Virtual memory


  Logical memory created from hard disk space by the operating system, provides lower speed data access