Nat 5 Computing - Data Representation

Nat 5 Computing
Data Representation
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Slide 1: Slide
ComputingUpper Secondary (Key Stage 4)GCSE

This lesson contains 12 slides, with interactive quizzes and text slides.

Items in this lesson

Nat 5 Computing
Data Representation
Revision

Slide 1 - Slide

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This is a mindmap.
What comes to mind when you think about:
Data representation

Slide 2 - Mind map

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Binary Numbers:
Convert from binary to denary and vice-versa.
Everything stored by a computer is stored using Binary –0 & 1's
Floating point representation:
The mantissa and exponent are stored as separate numbers. The computer recreates the number for calculations when it needs to. 
Vector graphics :
store a picture by storing each objects attribute –e.g. the instructions to draw the shape.
- Rectangle-(height, width, x, y, fill colour, line colour)
- Ellipse-(cx, cy, rx, ry, fill colour, line colour)
- Line-(x1, y1, x2, y2, line colour)
- Polygon -any shape with 3 of more sides -(x1, y1, x2, y2, x3, y3, fill colour, line colour)
Text:
Each character is given an 8-bit ASCII Code
You must also need to make file size estimations
    1 character = 8 bits or 1 byte
Bitmap Images:
Computers stores, in binary, each pixel. Number of bits per pixel depends on the number of colours in the image –more colours, more bits.
- You must be able to estimate the file size = Width X Height X Colour Depth
- You must be able to compare and contrast different types of images and when these are most suited for certain uses
Key Content

Slide 3 - Slide

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A user enters the password below: GRK_0183_J
State how many bits would be required to store the password using extended ASCII code - 2022-Q9(c)(i) 1 mark

Slide 4 - Open question

10 x 8 = 80 bits
State a standard code used to represent text characters and the number of bits used to store each character. 2019 Q13(b) 2 marks

Slide 5 - Open question

ASCII (extended)
8 bits
A graphic designer creates a business card for a taxi company
State the name of a graphical object used in this design and one attribute of that object that can be altered by the graphic designer 2022 Q7 - 2 marks

Slide 6 - Open question

One mark for any object name from
  • ellipse/circle
  • text
  • rectangle/rect
  • polygon
  • line
One mark for any attribute of object
given from
  • x coordinate
  • y coordinate
  • (x, y) coordinates
  • line thickness
  • line colour
  • fill colour
  • length
  • breadth
The line below is stored as a vector graphic

State one attribute of this object. - 2019 Q12 1 mark

Slide 7 - Open question

One of:
  • x coordinate
  • y coordinate
  • thickness/width
  • colour
  • length
  • rotation/angle
  • transparency/opacity
  • layer
Sam takes pictures of floor layouts using a tablet device.
(i) The images are stored as bit-mapped graphics.
Describe how a bit-mapped graphic would be stored 2022 -Q10(d)(i) 2 marks

Slide 8 - Open question

Answer must include

• each pixel
• is stored as a binary value (bits)
The user interface design is implemented. It contains a bit-mapped graphic and some text.
(i) Describe how a bit-mapped graphic would be stored. 2019 Q13(b)(i) 2 marks

Slide 9 - Open question

One mark each for
  • pixels
  • each pixel stored as a binary value
The cruising speed of an aeroplane is 891.6 kilometres per hour. This value would be stored in a computer system using floating-point representation as shown below.
0·8916 × 10^3
Identify the mantissa and exponent in the above floating-point representation. 2022 Q5 2 marks

Slide 10 - Open question

One mark each for
• 8916 (mantissa)
• 3 (exponent) 
Convert the decimal number 60 into 8-bit binary 2022 Q1 1 Mark

Slide 11 - Open question

00111100
Must have 8 bits
Convert the following 8-bit binary number into denary.
1011 1001
2019 Q1 1 Mark

Slide 12 - Open question

185