Data Compression & Backup

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Data Compression Software

Data compression software allows users to store more data onto a certain disk.

Compression

Compression utilities reduce the amount of disk space needed to store a file by applying a lossless compression algorithm.
Lossless compression means that no quality is lost from the original file, and it can be restored to the original.

Decompression

Compression utilities can also decompress the compressed files to return them to their original versions.
Files must be decompressed in order to read them.

Uses of compression

Although we cannot read compressed files without decompressing them first, they are useful in many situations. For example:
- When a file won't be accessed regularly e.g. in archives.
- When a file is to be transferred on a network (to speed up transfer).

Backup Software

We store so much vital data on computers that losing this data could have catastrophic consequences.

Purpose of backup software

Backup software creates a copy of important data, so that it can be stored in an external location.
Having multiple copies of the data means that if something happens to one of the copies, we can restore it using another.

Full backup

A full backup is where a copy is made of everything on the system onto the backup media.
Full backups are slow processes and take up a lot of space.
It is very easy to restore a system from a full backup.

Incremental backup

An incremental backup is where only the files that have changed since the last backup are copied.
Incremental backups are faster and use less space.
It is more difficult to restore a system from incremental backups because:
- The most recent full backup must be applied.
- Every incremental backup since then must then be applied in the correct order.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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