ICT Unit 1

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  • Created by: Leila
  • Created on: 17-01-13 21:42
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  • ICT Unit 1
    • Hardware
      • Random Access Memory (RAM)
        • The computer's 'working memory'. Temporaily stores programs and data that are used at a given time. Contents can be changed and is lost when the computer is turned of. Known as 'volatile memory'
      • Read Only Memory (ROM)
        • Main use of ROM is to store the programme that runs when the computer is turned on which loads the operating system. Contents cannot be changed and isnt lost when computer is turned of. Known as 'non-volatile memory'
      • Bits and Bytes
        • Computers store and process data using binary numbers. A single unit in binary is called a bit which stands for binary digit. Computer memory is measured in bytes. One byte is made up of 8 bits.
        • The size of  a computer's memory is normally measured in killobytes (kB), megabytes (MB) and gigabytes (GB)
          • 1 kB = 1024 bytes
          • 1 MB = 1024 kB
          • 1 GB = 1024 MB
          • 1 TB (terabyte) = 1024GB
    • Main Components
      • Hardware= all the parts of the physical equipment which makes the computer.
      • Software= all the programs that allow the hardware to carry out the data processing
        • Two main types of computer software- system and application. Application is used in particular situations and can be general purpose ( same software used in different situations) or specialst (only be used in one situation)
          • Specialst software only performs one particular task. Examples include software for payroll, accounts, stock control, route planning and weather forecasting.
        • General purpose is software that can perform different related tasks. Word processors, spreadsheets, databases, graphics and presentation software are all examples of application software.
          • Two main types of computer software- system and application. Application is used in particular situations and can be general purpose ( same software used in different situations) or specialst (only be used in one situation)
            • Specialst software only performs one particular task. Examples include software for payroll, accounts, stock control, route planning and weather forecasting.
          • They are: relatively cheap, readily  available, can be installed quickly and easily, throughly tested and well supported with books and on-line help.
          • (see revision notes for examples of application software packages)
      • Why use computers?
        • Very fast, very accurate, can work 24 hours a day, 365 days a year, make some jobs possible.
      • Disadvantages of using computers:
        • Can replace people's jobs, hold personal information which could be missused, can fail and without them the job may not get done.
      • Processing data
        • Computers can: calculate, sort, search, store and draw.
    • Operating systems
      • An operating system is a set of programmesthat controls how the hardware and applications of a computer works. An OS is the way of communicating between the user and computer. OS loads and runs the other software application programmes and other jobs.
      • Functions of the operating system
        • Part 1: Enables communication between user and computer, loads and runs applications programmes as well as other jobs, will only run programmes written for that particular type of OS.
          • Part 2: handles input and output- taking data from input devices and sending it to RAM and taking output and sending it to correct output device.
            • Part 3: handles the transfer of data from memory to and from the backing storage devices, allocates memory space to programs and data, handles any error when software is running, manages a system security  with user ID's and passwords and provides a human-computer interface for the user.
      • Human-computer interface (HCI)
        • Part 3: handles the transfer of data from memory to and from the backing storage devices, allocates memory space to programs and data, handles any error when software is running, manages a system security  with user ID's and passwords and provides a human-computer interface for the user.
        • Method by which the user communicates with the computer, sometimes called the user interface. Two types of HCI are: command-line interface and graphical user interface.
          • Command- line interface
            • User types in instructions using command words. Main advantage is that, providing the user knows the commands, they can be quick to carry out, since they require less translation by the OS that GUI's. Can also be used in batch files to carry out repetitive administration tasks that would take a long time using a GUI.
          • Graphical user interface (GUI)
            • Most widely used type of graphical user interfaces are WIMP (Windows Icons Menu Pointer) systems. Main advantage of a GUI is it is easy to use. Main disadvantage is the large amount of memory, RAM and disk space is needed.
    • Types of computer
      • Mainframe computers
        • Process large amounts of data very quickly. Backing storage is provided on lots of disk drives.
        • A mainframe can have a large number of users connected to it at the same time.
        • Most powerful mainframes are called 'supercomputers' and are used for processing even larger and more complex amounts of data, such as in weather forecasting.
      • Personal computers
        • A typical PC system consists of: a base or tower that contains the processor, backing storage devices (hard disk drive), DVD drive, USB connections, Firewire and other connections. Input devices normally a mouse and keyboard. Output devices, typically a screen, printer and speakers.
        • PCs are single-user computers and used to be called 'microcomputers'.
      • Laptop (notebook)
        • An example of a portable computer. Screens and typically 35-47 cm and are used whilst travelling or at meetings.
      • Netbook
        • An even smaller version of a laptop, screens typically 20-25 cm.
      • Palmtop and PDA (personal digital assistant)
        • PDA'sare small hand-held devices with limited functionality (diary, contact lists, email)
          • If the PDA also has mobile phone capability, this is known as a 'smartphone'
        • Palmtops are small computers with a small number of apllications which can be synchronised with the main networks system.
      • Microprocessors
        • A microprocessor is a single integrated circuit (chip) that performs the functions of a central processing unit (CPU).
          • They are used to control devices such as washing machines, videos, burglar alarms etc.
            • Advantages
              • Reliable - no moving parts, chips are cheap, programmabble- so able to perform different functions.
            • Disadvantages
              • Wasteful to replace whole unit when it could be repaired, many of extra features may never be used, more complex- more to go wrong and break down.

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