This document discusses how data is represented in computer systems. It covers basic units of data like bits and bytes and larger units like kilobytes and megabytes. It also explains binary and hexadecimal number systems. Additionally, it discusses how other data types like characters, images, sound, and computer instructions are represented and stored in binary format. Key concepts covered include character sets, pixels, metadata, sample rates, bit rates, opcodes, and operands.

1. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Units

2. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Bit
Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte

3. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Binary

4. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Computers only
communicate via electronic
signals (on or off). These
are represented to human
by 1s and 0s.
You need to be able to
convert numbers to binary.

5. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Hexadecimal

6. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Binary numbers are
confusing for programmers
so hexadecimal are easier
to understand and use.
You need to be able to
convert numbers to
hexadecimal.

7. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Overflow

8. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
When two 8 bit
numbers are added
together and the result
does not fit into an 8 bit
number.

9. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Binary in
Characters

10. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Characters (A-Z…) are
all represented by
binary numbers so
computers can
understand them.

11. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Character
Set

12. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
The numerical values
for characters are
stored in a character
set.

13. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
ASCII

14. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
American Standard Code
for Information Interchange
An example of a character
set. Contains 7 bits worth
of characters (127), used
in English speaking
countries.

15. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
UNICODE

16. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Universal Code
An example of a
character set. Contains 3
bytes worth of characters
(64,000), used in all
countries.

17. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Pixel

18. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
An individual ‘dot’
within an image

19. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Metadata

20. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
The details to go with
an image (height,
width, colour depth,
resolution…)

21. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Colour Depth

22. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
The amount of bits used in each
pixel.
The more bits, the more colours.
1 bit = 2 colours (1 or 0)
2 bit = 4 colours (00,01,10 or 11)

23. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Resolution

24. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
The amount of pixels
per square inch of an
image.

25. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Sound in
Binary

26. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Sound is converted
into binary by
‘sampling’ the height of
the sound wave at
different intervals

27. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Sample Rate

28. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
How often the sound is
sampled.
The more the sound it
sampled, the more the
data will sound like the
original.

29. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Bit Rate

30. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
How much data is
recorded per sample.
The higher the bit rate,
the better the quality, but
the file size will be larger.

31. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Instructions
in Binary

32. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
When a peripheral
device sends an
instruction to the CPU
this is sent as binary. It is
broken into two bits, the
opcode and operand.

33. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Opcode

34. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
ADD 34
The opcode is the first
part, the instruction. This
example is saying that a
value needs to be
added.

35. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
Operand

36. Learning Objectives
REVISION
2.1.4 Representation of data
in computer systems
ADD 34
The operand is the
second part, the data.
This example is saying
that 34 needs to be
added.