Magnetic Storage

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How Magnetic Storage Works

The most common type of magnetic storage is the Hard Disk Drive (HDD).

Storing a bit

The value of each bit of data (0 or 1) is represented as a positively or negatively charged magnetic particle.
These particles are part of a magnetic disk called the platter.

Accessing data

Data could be stored anywhere on the disk, and so to read/write data we first need to find the location on the disk.
A magnetic read/write head is used to access the data while the platter spins.

Reliability

The HDD has moving parts.
Although the HDD is generally reliable, any device with moving parts will be subject to wear-and-tear.
HDDs can also be damaged by shocks. They are not robust.

Properties of Magnetic Media

To compare magnetic storage with the other types of media, it is important to understand the advantages and disadvantages of storing data magnetically.

Low cost

Magnetic media is very low cost per unit capacity.
This makes it an economical choice for storing large amounts of data.

Low speed

Magnetic media needs a high number of moving parts.
The high number of moving parts make magnetic media slow to access.

Good reliability

Magnetic media is reliable and tends to last for a long time.
Magnetic media is not robust, and tends to break on impact or during vibrations.

High capacity

Magnetic media can store a large quantity of data in a compact way.
This makes them a popular choice for archives as well as home computers.

Examples of Magnetic Storage

Magnetic storage can be used in more devices than just Hard Disk Drives (HDDs). Magnetic storage is also used for magnetic tape and more.

Hard Disk Drives (HDD)

HDDs are often used as the main form of secondary storage in a computer system.
HDDs hold the operating system, applications, and user data.

Magnetic tape

Magnetic tape used to be popular for distributing content such as:
- Audio.
- Video.
- Software.
Nowadays, tape is only used for:
- Some video cameras.
- Making backups.

Hybrid drives

Some modern devices have both magnetic and solid state storage.
The combination of magnetic and solid state storage is known as a hybrid drive, and offers the benefits of both systems.

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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