What is secondary storage?

Secondary storage is non-volatile storage that keeps programs and files long term. Data on secondary storage must be loaded into RAM before the CPU can use it.

Why do computers need secondary storage?

RAM is volatile, so files and programs would be lost when the power is switched off. RAM is also too small to hold everything a user wants to keep.

Give three examples of optical storage media.

CDs, DVDs and Blu-ray discs are all optical storage media.

OCR GCSE Computer Science J277

Systems Architecture

Topic overview CPU components and the fetch-execute cycle Factors affecting CPU performance Embedded systems

Memory and Storage

Topic overview RAM, ROM, cache and virtual memory Secondary storage: magnetic, optical and solid state Data units and storage capacity calculations Binary, denary and hexadecimal conversions Binary addition, overflow and binary shifts Character sets, ASCII and Unicode Bitmap images, colour depth and resolution Sound sampling, sample rate and bit depth Lossy and lossless compression

Computer Networks, Connections and Protocols

Topic overview LANs, WANs and network performance Client-server and peer-to-peer networks Network hardware, DNS, hosting and the cloud Star and mesh topologies Wired and wireless connections, IP and MAC addresses Protocols, standards and layers

Network Security

Topic overview Malware, social engineering and brute-force attacks Denial of service, data interception and SQL injection Identifying and preventing vulnerabilities

Systems Software

Topic overview User interfaces, memory management and multitasking Peripheral, user and file management Utility software

Ethical, Legal, Cultural and Environmental Impacts of Digital Technology

Topic overview Ethical and cultural issues in digital technology Environmental impact of digital technology Privacy and digital technology Computer Science legislation and software licences

Algorithms

Topic overview Abstraction, decomposition and algorithmic thinking Flowcharts, pseudocode and structure diagrams Trace tables and correcting algorithms Linear and binary search Bubble, merge and insertion sort

Programming Fundamentals

Topic overview Variables, constants, operators and assignment Sequence, selection and iteration Data types and casting String manipulation and file handling Arrays, records and SQL Functions, procedures and random numbers

Producing Robust Programs

Topic overview Defensive design, input validation and authentication Writing maintainable code Testing, errors and test data

Boolean Logic

Topic overview Logic gates and truth tables Combining gates in logic diagrams

Programming Languages and Integrated Development Environments

Topic overview High-level and low-level languages and translators The integrated development environment (IDE)

Memory and Storage

Secondary storage: magnetic, optical and solid state

3 things to know
J277/01

Overview

Why secondary storage is needed, magnetic, optical and solid state storage, comparing capacity, speed, portability, durability and reliability, and choosing storage for cameras, backups and consoles.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Name the three types of secondary storage, with one example of each.

Key term

How does each type of secondary storage record data?

Key term

What do capacity, speed and portability mean when comparing storage devices?

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 files long term. Data on secondary storage must be loaded into RAM before the CPU can use it.
2
Why do computers need secondary storage?
Model answer
RAM is volatile, so files and programs would be lost when the power is switched off. RAM is also too small to hold everything a user wants to keep.
3
Name the three types of secondary storage, with one example of each.
Model answer
Magnetic storage includes the hard disk drive. Optical storage includes the DVD. Solid state storage includes the USB flash drive.
4
Give three examples of optical storage media.
Model answer
CDs, DVDs and Blu-ray discs are all optical storage media.
5
How does each type of secondary storage record data?
Model answer
Magnetic storage records data as magnetised areas. Optical storage holds data that is read using a laser. Solid state storage holds data electronically and has no moving parts.
6
What do capacity, speed and portability mean when comparing storage devices?
Model answer
Capacity is how much data a device can hold. Speed is how quickly data can be read and written. Portability is how easy a device is to carry around.

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Systems Architecture

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