Nat 5 Computing Science

Data Representation
1. Binary
  2. Everything stored by a computer is stored using Binary- 0s and 1s
2. Floating Point Representation
  1. The mantissa and exponent are stored as separate numbers. The compute recreates the the number for calculations when it needs to.
  2. The greater the number of bits sued to store the mantissa, the more precise the number will be.
  3. The greater the number of bits used to store the exponent, the greater the range of numbers can be represented.
  4. The mantissa will store the precision of the number and the exponent will store the range of numbers.
3. Vector Graphics
  1. Vector graphics store a picture by storing each object's attributes eg. Instructions to draw the shapes.
  2. Rectangle
    1. Co-ordinates: x, y Height, Width, Fill Colour, Line Colour
  3. Ellipse
    1. Co-ordinates: Cx, Cy, Rx, Ry Fill Colour, Line Colour
  4. Line
    1. Co-ordinates: x1, y1, x2, y2 Line Colour
  5. Polygon (Any shape with 3 or more sides)
    1. Co-ordinates: x1, y1, x2, y2, x3, y3... Fill Colour, Line Colour
4. Bit-Mapped Graphics
  1. Computers store, in binary, each pixel in a 2d grid.
  2. Number of bits per pixel depends on the number of colours in the image- more colours, more bits.
Computer Structure
1. Components
  1. All components are part of the Processor
  2. Control Unit
    1. Controls the sequencing of fetching, decoding and executing instructions.
  3. Arithmetic & Logic Unit (ALU)
    1. Performs all calculations and logical operations.
  4. Registers
    1. Temporary memory locations within the processor.
2. Memory
  1. All memory locations within RAM (Random Access Memory) are given a unique address so that the computer can read and write data to that location correctly.
3. Buses
  1. Address Bus
    1. This identifies the memory location that is going to be read from or written to.
  2. Data Bus
    1. This transfers the data between the processor and memory, and vice versa.
4. Translators
  1. They translate high-level program code to binary.
  2. Interpreter
    1. Translates the program code into machine code one line at a time and executes each line immediately after it has translated it.
      1. Machine code is not retained so program must be translated each time. Therefore good for finding errors.
  3. Compiler
    1. Translates the whole program and then saves the translated machine code version. This means that the translated code can be run again and again.
      1. Used for programs that are ready for release.
Environmental Impact
1. Energy Use of Computer Systems
  1. It is estimated that there are two billion computer systems in use throughout the world- these all use energy.
  2. As users we need to consider how to reduce unnecessary energy use.
2. Methods to Reduce Energy Usage
  1. Power Down Settings
    1. Automatically power down after a period of inactivity.
    2. Control setting for single components.
  2. Leaving Computers on Standby
    1. Power consumption is reduced.
  3. Settings on Monitors
    1. Reduce Brightness
    2. Activate Efficiency Mode
    3. Use Energy Efficient Monitors
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Nat 5 Computing Science

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	Created by Madeline Delaney about 3 years ago