Nat 5 Computing - Data Representation

• Computing
• Upper Secondary (Key Stage 4)
• GCSE

Nat 5 Computing

Data Representation

Revision

This is a mindmap.

What comes to mind when you think about:

Data representation

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

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

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

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

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

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

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

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

One mark each for

• 8916 (mantissa)

• 3 (exponent) 

Convert the decimal number 60 into 8-bit binary 2022 Q1 1 Mark

00111100

Must have 8 bits

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

185