Edexcel curriculum (2015)

Algorithms

Application sof'wr

Ascii

Binary

Cache

Client-Server

Cloud

Compression

Computational think

CPU

Cyber security

Database

Fetch-d-e cycle

Embedded system

Encryption

Environment

Ethics

File size

Flow chart

Hexadecimal

High Level language

ISP/Internet

Law & Legislation

Logic

Magnetic HDD

Networking

Open source

Operating system

Optical storage

Peer to peer

Pictures (data rep)

Protocols

Run length encoding

RAM

ROM

Simulation software

Solid state HD

Sound

Stored program

Utility Sof'wre

Compression

Answer
​Any one of:
To reduce download time/increase transfer speed
To reduce amount of storage space required

Lossy compression

Answer
​Any two of:
Not all pixels are recorded
Quality/detail reduced
Only suitable when images have lots of the same pixels
Cannot reproduce original using the lossy data

Compression

Answer
​Any two of the following:

File sizes / download times will be reduced. (1)
Some loss of image data / image quality will occur. (1)
JPEGs allow image quality to be fine-tuned / the level of compression to be adjusted. (1)

Compression - lossless

Answer
​An explanation that makes reference to the following points:
• lossless compression ensures that no data is lost (1)
• so that the desktop published file can be restored so that it is exactly the same as the original (1)

Compression - lossy

Answer
​ Any two from:
• Data is removed during the compression process (1)
• The removed data is not normally noticed by a human (sight, sound) (1)
• The original contents of the file cannot be restored exactly (1)

Compression - RLE

Answer
​• Letters in correct order (1)
• Correct number (1)
Either: 3b 1r 4g 2r
Or
b3 r1 g4 r2

Run length encoding

Answer
​​Any one of:
R4B2R1Y3
R4B2RY3
4R2BR3Y
4R2B1R3Y
With one incorrect character or digit award a maximum of 1 mark.

Run length encoding

Answer
​This sequence has very few repeated patterns (1), therefore using a RLE will not lead to a significant reduction in the file size / not compress the image very much. (1)