GCSE Computing Data Key terms

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Units

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Bit

Nibble

Byte

Kilobyte

Megabyte

Gigabyte

Terabyte

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Binary

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Hexadecimal

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Overflow

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Binary in Characters

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Characters (A-Z…) are all represented by binary numbers so

computers can understand them.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Character Set

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

The numerical values for characters are

stored in a character set.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

ASCII

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

UNICODE

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Pixel

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

An individual ‘dot’ within an image

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Metadata

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

The details to go with an image (height,

width, colour depth, resolution…)

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Colour Depth

Learning ObjectivesREVISION

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)

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Resolution

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

The amount of pixels per square inch of an

image.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Sound in Binary

Learning ObjectivesREVISION

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

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Sample Rate

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Bit Rate

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Instructions in Binary

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Opcode

Learning ObjectivesREVISION

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.

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Operand

Learning ObjectivesREVISION

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.