How does a magnetic hard disk drive store data?

A hard disk stores data on spinning platters coated in magnetic material. A read/write head magnetises tiny areas in one of two directions to represent 1s and 0s.

Why is a magnetic hard disk slower to access than a solid state drive?

A hard disk must spin its platters and move its head to the right place before reading. A solid state drive has no moving parts, so data is reached almost instantly.

What are the advantages of magnetic hard disks?

Magnetic hard disks offer very large capacities at a low cost per gigabyte. Hard disks suit servers and backups that hold large amounts of data.

Edexcel GCSE Computer Science 1CP2

Computational Thinking

Topic overview Decomposition, abstraction and subprograms Algorithms, flowcharts and pseudocode Operators and trace tables Logic errors, test data and efficiency Searching and sorting algorithms Truth tables

Data

Topic overview Binary, states and unsigned integers Two's complement Binary addition, overflow and shifts Hexadecimal ASCII and the limits of binary representation Bitmap images Sound sampling Storage units, file sizes and compression

Computers

Topic overview Von Neumann architecture and the fetch-decode-execute cycle Secondary storage: magnetic, optical and solid state Embedded systems Operating systems Utility software and robust software Low-level and high-level languages and translators

Networks

Topic overview LANs, WANs and the structure of the internet Wired and wireless connectivity and network speed Network protocols The four-layer TCP/IP model Bus, star and mesh topologies Network security and protection

Issues and Impact

Topic overview Environmental impact of digital devices Personal data: privacy, ownership and consent Artificial intelligence, machine learning and robotics Intellectual property: copyright, patents, trademarks and licences Malware, hacking and social engineering Protecting digital systems and data

Problem Solving with Programming

Topic overview Readable code, debugging and testing Selection and loops in Python Data types, conversion, variables and constants String handling Lists, two-dimensional lists and records Keyboard input, screen output and CSV files Validation and authentication in Python Operators, functions and variable scope Turtle graphics

Computers

Secondary storage: magnetic, optical and solid state

3 things to know
Paper 1

Overview

Why secondary storage is needed, how magnetic, optical and solid state devices store data, their advantages and disadvantages, and choosing storage for a given job.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is secondary storage?

Key term

Why does a computer need secondary storage as well as RAM?

Key term

How does secondary storage compare with main memory for speed and capacity?

Questions from this subtopic

Each one with the model answer underneath.

1
What is secondary storage?
Model answer
Secondary storage is non-volatile storage that keeps programs and data when the power is off. Hard disk drives, solid state drives and optical discs are examples.
2
Why does a computer need secondary storage as well as RAM?
Model answer
RAM is volatile and loses its contents when the computer is switched off. Secondary storage keeps the operating system, programs and files permanently.
3
How does secondary storage compare with main memory for speed and capacity?
Model answer
Secondary storage is much slower to access than RAM. Secondary storage holds far more data for the same cost.
4
How does a magnetic hard disk drive store data?
Model answer
A hard disk stores data on spinning platters coated in magnetic material. A read/write head magnetises tiny areas in one of two directions to represent 1s and 0s.
5
Why is a magnetic hard disk slower to access than a solid state drive?
Model answer
A hard disk must spin its platters and move its head to the right place before reading. A solid state drive has no moving parts, so data is reached almost instantly.
6
What are the advantages of magnetic hard disks?
Model answer
Magnetic hard disks offer very large capacities at a low cost per gigabyte. Hard disks suit servers and backups that hold large amounts of data.

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