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What is Storage
• Secondary Storage devices ensures data is stored permanently so that it can be used again at a later date.
• Storage medium is the name given to the device that actually holds the data.
• Sometimes the storage medium is fixed i.e. magnetic coated disks build into hard drive.
• Sometimes the storage medium is removable from the device i.e. CD ROM that can be taken out of the drive.
Think about what we store:
Documents, Images, Video, Music, Software, Games etc.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
File Sizes
Storage devices or files sizes are measured in:
Kilobytes (KB), Megabytes (MB), Gigabytes (GB) and Terabytes (TB)
1 KB
1 MB
1 GB 1 TB
1000 Bytes

• 1000


• 1000


• 1000
  1000 KB
  1000 MB
  1000 GB
  Diagram not to scale
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Data Storage Capacity
Floppy Disk
1.4MB
CD-ROM
700MB
DVD 4.7GB
Data storage devices have very different capacities. Over time the capacity has increased which has allowed for more data to be stored:
Blu-Ray
25 GB – 128GB
Hard Drive 8 TB
Magnetic Tape Up to 185 TB
Increase in storage capacity
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Type of Access
Serial (sequential Access)
• Files are stored one by one in a sequence
• Must search through the files one by one until you get to the one you
want.
• Example: VHS tape, Cassette Tape, Magnetic Tape
Start 1
2
3
4
5
6
7
8
9
End 10
Direct (Random Access)
• Stores files so that they can instantly be accessed
• No need to search through files to get to the one you want
• Example: DVD, CD ROM, Blu-ray, external hard drive, flash drive
Start 1
2
3
4
5
6
7
8
9
End 10
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Main Memory Vs Backing Storage
Main Memory
• Sometimes known as Internal Memory or primary memory.
• Includes RAM and ROM
• Usually used to store data temporarily (in the case of RAM).
• Usually used to store data while it is being processed by the CPU.
• Is volatile – means data will be lost if computer is turned of.
Backing Storage
• Backing storage some known as secondary storage.
• Name for all other storage devices which are part of a computer
like hard drive.
• Usually used to store data over a long time.
• Usually used to store application software, operating system
software, files etc.
• Is Non-volatile - Means data will not be lost of computer is
turned off.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
Fixed Internal
3.1 Storage devices and media
Hard Drive
Magnetic Storage Devices
Use:
Main backing storage device used by all computers to store:
• Operating Systems & System Files
• Applications
• Files (Documents, Images, videos, audio etc.)
Access Type: Direct (Random Access)
Advantages:
Disadvantages
• Less likely to break as fixed.
• High storage capacities compared to external drives.
• Fast data transfer rate.
• More moving parts compared to solid state drives.
• Incorrect shut down procedure could cause hard drive to malfunction.
• Magnetic storage media devices store data in the form of tiny magnetised dots.
• These dots are created, read and erased using magnetic fields created by very tiny electromagnets.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
Portable
3.1 Storage devices and media Magnetic Storage Devices
Hard Drive
Use:
This device connects to the computer using the USB Port. External Hard drives are used to store:
• Personal backup data.
• Transfer files between computers/devices
Access Type: Direct (Random Access)
Advantages:
Disadvantages
• Portable – transfer files between computers.
• High Storage capacity compared to optical disks.
• More prone to errors than fixed hard drive.
• Could be damaged if incorrectly ejected from computer.
• Magnetic storage media devices store data in the form of tiny magnetised dots.
• These dots are created, read and erased using magnetic fields created by very tiny electromagnets.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Magnetic
Magnetic Storage Devices
Tapes
Use:
• Large organisations make daily backups of their networks on to Magnetic Tapes
• Long-term archiving of data.
Access Type: Serial
Advantages:
Disadvantages
• Huge storage capacity compared to fixed and portable hard drives.
• Stored away in a fire proof safe.
• Robust – last for long time
• Slower Access
Tape reader has to start at the beginning of the tape and continue fast forwarding until it gets to the piece of data
that needed.
• Magnetic storage media devices store data in the form of tiny magnetised dots.
• These dots are created, read and erased using magnetic fields created by very tiny electromagnets.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
CD-ROM
Optical Media
Use:
CD-ROM disks are read-only. CD-ROMs are normally used to store:
• Audio CDs
• Software Applications
• Device Drivers
• Optical storage devices save data as patterns or dots.
• Data is read by bouncing the laser beam off the surface off the medium.
Access Type: Direct
Advantages:
Disadvantages
• Hold more data than floppy disks.
• Cheaper than hard drives and USBs.
• Compatible with audio systems.
• Data transfer rate is slower compared to other storage medium.
• Not Robust - easily be damaged or scratched.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
DVD-Rom
Optical Media
Use:
DVD-ROMs disks are read-only. DVD-ROMs are normally used to store:
• DVD Movies
• Software Applications
• Computer Games
• Optical storage devices save data as patterns or dots.
• Data is read by bouncing the laser beam off the surface off the medium.
Access Type: Direct
Advantages:
Disadvantages
• Hold more data than CD- ROMS.
• Can store larger applications.
• Videos is higher
resolutions.
• Data transfer rate is slower compared to other storage medium.
• Have to buy a separate DVD player.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Blu-Ray
Optical Media
Use:
Blu-Ray disks uses a blue laser instead of red laser used with CD/DVD ROMs. Blu-Ray disks are normally used to stored:
• HD Movies
• Large Software/Game Applications
• In camcorders in cartridge form.
• Optical storage devices save data as patterns or dots.
• Data is read by bouncing the laser beam off the surface off the medium.
Access Type: Direct
Advantages:
Disadvantages
• Large storage capacity used to store HD video content.
• Access Speeds are greater than other optical medium.
• Secure Encryption System to minimise chance of copyright.
• More expensive compared to other optical media.
• Separate player required –
more expensive.
• Not all movie titles
available on Blu-Ray.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Optical Media
R – Write once only
RW – Can be written to or read many times.
CD-R and DVD-R
CD-RW and DVD-RW)
DVD RAM
Overview
CD-R and DVD-R are only recordable once. Once the process has been finalised then the disks become Read Only.
• Backup of data
• Audio CDS
CD-RW and DVD-RW allows for data to be written, erased and rewritten many times.
• Used in CCTV
• Record television programs
DVD RAMS are used when data constantly needs to be re-written. DVD RAMS can hold up to 10GB of data and commonly used in recording equipment.
Advantages
• Cheaper than RW disks.
• Can be reused many times.
Long life, large capacity, and can be rewritten many times.
Disadvantages
• Not compatible with all players.
• If disk has a burn error it can not be used again.
• Can be expensive.
• Data could be
overwritten.
Not compatible with all playback formats.
Can be expensive.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Describe the differences between DVD-R, DVD-RW, DVD RAM and DVD ROM?
Key Words: Read only, Recordable once, Re-writable, Constantly re- written, capacity, recording equipment.
Exam Question
DVD-R are only recordable once. Once the process has been finalised then the disks become Read Only. DVD-RW allows for data to be written, erased and rewritten
. DVD-ROM are Read Only and typically contain software, movies and
many times
games. are used when data RAMS can hold up to 10GB of data ( recording equipment. DVD RAM will and the DVD-ROM as it is
-written. DVD ) and commonly used in
than the DVD-R, DVD-RW . However it will be more expensive.
DVD RAMs
constantly needs to be re
higher capacity
typically last longer
more durable
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Compare and contrast the use of optical discs and the use of fixed magnetic disks to store data.
Exam Question
Optical discs such as CDs DVDs and Blu-ray discs are
. Magnetic disks are .
Both have however more time would be taken to write to an
. Optical
discs are more portable and cheaper to buy. However they are more prone to
as they can easily be . Magnetic disks however have a
to store more information. Optical discs are used to store in contrasts magnetic disks store
.
read from and written to using
a laser beam
direct access
disc compared to a magnetic disc due to slower access and transfer rates
scratched or broken
read from and written to using read/write heads
damage
optical
higher capacity
music, software
videos,
installed applications, system and
user files
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Solid ‘state’
• Solid-state storage devices are based on electronic circuits with no moving parts.
• Solid-state storage devices store data using a special type of memory called flash
memory.
• USB/Memory Cards use Direct Access
Examples
USB Memory Stick
Memory Card
Uses:
Used to transfer files/backup (work) between computers.
Used to store files on digital cameras, mobile phones and mp3 players.
Advantages
• Portable & Small • Robust
• large capacities
• No need for additional
drivers/software
• Very small and can be removed and placed in other devices.
• Robust
Disadvantages
• Easy to loose
• USB could be damaged if not
ejected correctly.
• Smaller storage capacities.
• Quite expensive.
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Compare and contrast the use of a Fixed Hard drive, portable hard drive and a USB?
Exam Question
A fixed hard drive is the found in a computer system.
on to the fixed hard disk. It is less
because it is fixed into the computer whereas the portable hard drive and the USB drive could be damaged when ejecting. In addition the fixed hard drive will have a compared to the portable and USB storage. Files
between computers when using a portable hard drive and a USB drive. However the USB drive will me more portable than the portable hard
drive. Both the portable and the USB drive is use to back up files however the portable hard drive will be used to typically back up larger files.
primary storage device
Application and system software will be installed
prone to damage
higher capacity
can be easily transferred
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Discuss why you use a USB to backup data compared to optical disks? Key Words: larger capacity, more portable, more robust, accessibility to USB ports
Exam Question
A USB drive is more suitable to backup data compared an optical disk because it tends to have a higher storage capacity. In addition it is much quicker to copy files to a USB Drive rather than burning files onto an optical disk. Furthermore the USB drive is and . Finally not all computers would have an optical disk
however many have .
Solid state devices do not having any moving parts and can be referred to as flash memory. A are examples of solid state storage devices. They are and very . They are quite expensive to buy and can if not correctly ejected from the computer. The devices are available in different capacity and are more robust compared to optical disks.
more portable
robust
drive
accessibility to USB ports
Discuss the advantages and disadvantages of solid state storage devices?
Key Words: portable, smaller, expensive, robust, capacity, lost, damage
USB drive or memory cards
typically smaller
portable
be easily lost or damaged
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Chapter 3: Storage devices and media
ICT IGCSE Theory – Revision Presentation
3.1 Storage devices and media
Backup
Backup means making one or more copies of your data in a different storage medium.
Why?
• You could delete a file by accident
• Your computer could break down
• Your computer could get infected by a virus which could edit
data
• Your laptop is stolen or becomes damaged.
• Data could be corrupted by hackers.
• Most businesses use computers to store very important data (customer records, financial information, designs for products, etc.)
• If this data is lost, then this would cause disruption to the business. Backing