GCSE Computing Data Key terms

Learning ObjectivesREVISION

2.1.4 Representation of data in computer systems

Units



Bit

Nibble

Byte

Kilobyte

Megabyte

Gigabyte

Terabyte



Binary



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.



Hexadecimal



Binary numbers are confusing for programmers so

hexadecimal are easier to understand and use.

You need to be able to convert numbers to

hexadecimal.



Overflow



When two 8 bit numbers are added

together and the result does not fit into an 8 bit

number.



Binary in Characters



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

computers can understand them.



Character Set



The numerical values for characters are

stored in a character set.



ASCII



American Standard Code for Information Interchange

An example of a character set. Contains 7 bits worth

of characters (127), used in English speaking countries.



UNICODE



Universal Code

An example of a character set. Contains 3 bytes worth of characters (64,000), used in all

countries.



Pixel



An individual ‘dot’ within an image



Metadata



The details to go with an image (height,

width, colour depth, resolution…)



Colour Depth



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)



Resolution



The amount of pixels per square inch of an

image.



Sound in Binary



Sound is converted into binary by

‘sampling’ the height of the sound wave at different intervals



Sample Rate



How often the sound is sampled.

The more the sound it sampled, the more the data will sound like the

original.



Bit Rate



How much data is recorded per sample.

The higher the bit rate, the better the quality, but the file size will be larger.



Instructions in Binary



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.



Opcode



ADD 34

The opcode is the first part, the instruction. This example is saying that a value needs to be added.



Operand



ADD 34

The operand is the second part, the data. This

example is saying that 34 needs to be added.

Education

GCSE Computing Data Key terms