Block 3: Compression & Encryption and Block 4: Computers &
Assembly Language Programming
Lesson 1 activities
Activity 1.1
Fill in this table to help you see what a difference compression makes to file size.
File A
How many characters does
the file contain?
What type of content does
the file contain?
What is its file size before
compression?
What is its file size after
compression?
What is its compression ratio
(decompressed
size/compressed file size)?
Which file compresses the most? Explain why.
File B
File C
Activity 1.2
Your teacher is going to read out a series of binary numbers. The first pair of binary
numbers represents a colour code as follows:
00 = blue
01 = white
10 = yellow
11 = green
The second set of binary numbers represents the run length of the colour. So, for
example, 00, 1101 represents 13 blue pixels.
Assuming each of the squares in the grid below represents one pixel, listen to the
series of binary numbers and shade the squares. The first line of pixels has been
done for you.
Line 1: 00 0001 01 0011 00 1100
Activity 1.3 (homework)

Use four different colours to “draw” an image in the grid below.

Now encode the image using a 2-bit binary number to represent the colour depth and a 4-bit
binary number to specify the run length of the pixels to be filled with that colour.
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
Line 11
Line 12
Line 13
Line 14
Line 15
Line 16