The ICT Lounge
 
Section 3.4:
Magnetic Storage Media
 
In this section you will see the 4 different types of magnetic storage media.
  • Fixed hard disk drive
  • Portable hard disk drive
  • Floppy disk
  • Magnetic tape

For each we will discuss features, uses, advantages/disadvantages.

Key Concepts of this section:
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Know the 4 different types of magnetic storage media.
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Understand the uses of each magnetic media.
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Be able to discuss advantages and disadvantages of each magnetic media.

Examples of Magnetic Storage Media
Key Words:
Fixed Hard Disk Drive , Portable Hard Disk Drive, Floppy Disk, Magnetic Tape

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The table below shows you some examples of magnetic storage media. Click each of the media to move to more information:

Fixed Hard Disk
Drive
Portable Hard Disk Drive
Floppy Disk
Magnetic Tape
 
REMEMBER!

Magnetic storage media uses a magnatised surface area in order to hold bits of information.
NOTE:
Click the images to the left to move to more information about each one.

 

 
(Direct Access)
(Direct Access)
(Direct Access)
(Serial Access)

 

 

 

 


Breakdown of each output device:
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The following sections will help summarise each of the 4 different magnetic storage media. For each one you will see:




  • Information about the media
  • Uses of the media
  • Advantages of the media
  • Disadvantages of the media
Fixed Hard Disk Drive
Information:
Examples:
A summary of a fixed hard disk drive.
(Click to zoom)
 
Fixed hard disk drives are designed to be 'fixed' into the computer and not removed.
 
Fixed hard disk drives store data on magnetically coated disks (known as platters).
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Used on all computers and are the main method of storing data. This is because they are capable of very fast direct access of files and have very large storage capacities.

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The disc surface (Platter) is coated in a magnetic film which is where the data is stored.

These have read/write heads which allow data to be written to (saved) or read (used) from the disc.

The read/write heads (along with direct data access) allow for
very fast data access speeds.

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Hard Discs are used to store operating systems, software applications and all other files.

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Typical storage spaces are 250 gigabytes up to 4 terabytes (4,096 gigabytes).

Uses of Fixed Hard Disk Drives:
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Used to store the operating system and applications software (Windows, Word, Excel etc).

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Used for storing files and documents (music and homework for example).
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Real-time systems (robots, chemical plant control systems) and online systems (booking airline tickets etc) use hard disc drives to store data.

This is because real-time / online systems require data to be processed very quickly. Fixed hard disk drives have very fast data access speeds and so can handle this.

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Used in file-servers on computer networks to store files
(Like the student: drive in your school is used to store your work).


Advantages/Disadvantages of Fixed Hard Disk Drives:
Advantages
Disadvantages
Fast read/write times (Saves data to disk and reads back from it quickly).
Can be damaged easily when computer is not shut down properly (Disc crash!).
Huge capacities (Can store thousands of movies and music files).
Not portable as they are designed to be ‘fixed’ into computer and not removed
Very easy to update/delete files
Portable Hard Disk Drive
Information:
Examples:
A summary of a portable hard disk drive.
(Click to zoom)
 
Portable hard disk drives are protected from damage by a tough outer casing.
 
Portable hard disk drives are small and light.
 
Portable hard disk drives connect to almost any other computer via usb..
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Works in a similar way to fixed hard discs but are connected to the computer externally via a Universal Serial Bus (USB) port.

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They use direct data access methods which makes reading/writing of data very fast.

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Portable Disc Drives are designed to be transportable.

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They come with a USB Cable to allow for easy attachment to other computers which allows for easy backing up / sharing of files.

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Because they are used outside of the computer they come with protective casing to avoid physical damage to the disc drive.

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Typical storage spaces are 250 gigabytes up to 3 terabytes (3,072 gigabytes).


Uses of Portable Hard Disk Drives:
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Like fixed hard drives, they are used to store large files (such as video).

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Can be used as portable back-up systems to avoid loss of data.

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Used to transfer data, files and software between computers via USB connectivity.

Their protective casing makes them harder to damage whilst in transport.


Advantages/Disadvantages of Portable Hard Disk Drives:
Advantages
Disadvantages
Fast read/write times (direct data access).
Small size makes them easy to misplace or have stolen.
Huge capacities. (Thousands of movies and music files)
More expensive than other forms of storage
Small and light with protective casing.
(Makes them very portable)
Protective casing will only protect against minor bumps. If the device is dropped it can still become damaged.

Note: This is always a risk when transporting data externally!
Designed to plug into almost any computer via USB ports.


Floppy Disk
Information:
Examples:
A summary of a floppy disk.
(Click to zoom)
 
The magnetic plastic disk is protected by plastic casing and a metal sleeve.
 
Floppy disks are read/written to using floppy disk drives.
 
Floppy disks are now doomed!
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Old method of portable data storage where information is held on a thin plastic disc.

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Data on a floppy disk is read/written by a floppy disk drive which rotates the disk.

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As the disc rotates, a read/write head is used to add or read data.

The data is read/written using direct data access methods.

Even though floppy disks use direct data access, their data transfer rates are very slow. Good job they can only store 1.44MB!!

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The disc of plastic is protected by a retractable metal sleeve and hard plastic casing. A small notch provides write protection (prevents accidentally copying over work).

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Maximum storage on a floppy disc is only about 1.44 MB (700 pages of text).

Floppy disks do not have high enough capacities to store large modern files. This has made them obsolete (useless) and computers no longer have floppy disk drives installed.


Uses of Floppy Disks:
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Can still be used where very small files need to be transferred/stored (e.g. small word processed documents).

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Write protect facility is useful to prevent accidental overwriting of data.


Advantages/Disadvantages of Floppy Disks:
Advantages
Disadvantages
Cost very little to buy.
Very low storage capacity when compared to other media (1.44 Mb).
Can be write protected easily which protects against accidentally copying over files.
Very few modern computers have floppy disc drives (device used to read the disk).
Very small, light and easy to carry (portable).
Floppy discs are very delicate and easy to damage (Not robust).
Slow data transfer rate (Takes a long time to save/read from the disk).
Magnetic Tape
Information:
Examples:
A summary of magnetic tape.
(Click to zoom)
 
Magnetic tape is a magnetic coated plastic
wrapped onto a reel.
 
Magnetic tape uses serial (sequential) access to read/write data. It works much like a movie film reel.
Magnetic tape is one of the oldest forms of computer data storage media and it can store vast amounts of data.
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This is one of the oldest forms of computer data storage.

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Magnetic tape is a thin strip of magnetic coated plastic which is wrapped onto a reel.

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Data is stored on the magnetic plastic in the form of 1’s and 0’s (binary numbers).

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Data is written to and read from in sequence (i.e. in order) which is also known as 'serial access'.

Remember:
Serial Access works a bit like a video tape. To access something in the middle of the tape you need to start at the beginning then fast-forward until you get to the part you need.

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This type of storage media has a very slow data access rate.

Because it is so slow, It is useless for real-time applications (where what is stored is constantly being updated).

The slow access speeds makes it useless for holding data during real-time applications (e.g. alarm systems). This is because in real-time applications, stored data needs to be constantly and quickly updated.

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Sony have developed magnetic tape capable of storing a huge 185TB of data.


Uses of Magnetic Tape:
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Used where extremely large amounts of data need to be backed up.

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Used where speed of reading/writing of data is NOT a priority.

For Example:
Magnetic tape is used to hold data in batch processing applications such as clearing bank cheques and producing payslips.

It can be used here because speed is not important. These jobs are usually left running at night when everyone has gone home.

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Used for backups of computer networks in schools and business.

For Example:
Your school files are frequently backed up on the school's network.


Advantages/Disadvantages of Magnetic Tape:
Advantages
Disadvantages
Less expensive than the equivalent capacity hard disk drive.
Very slow data access/transfer (Reading data back from the tape is slow).
Very robust (Not easily damaged).

Needs another tape to update data

For example: original tape + tape with the changes = updated tape.

Very large storage capacities (Up to 185 terabytes or 185 trillion characters).

Activity!

Click the above task and write-up the required information about magnetic storage media.

Links to Theory Units:
Section 4: Networks and the Effects of using them
Section 6: ICT Applications
Section 7: The Systems Life Cycle
Section 8: Safety and Security
Section 9: Audience
Section 10: Communication
 
Links to Practical Units:
Section 11: File Management
Section 12: Images
Section 13: layout
Section 14: Styles
Section 15: Proofing
Section 16: Graphs and Charts
Section 17: Document Production
Section 18: Data Manipulation
Section 19: Presentations
Section 20: Data Analysis
Section 21: Website Authoring