The ICT Lounge
Section 3.3:
Storage Media Introduction
In this section you will be introduced to the 3 main types of storage media:
  • Magnetic storage media
  • Optical storage media
  • Solid state storage media
We also discuss storage media capacity, including kilobytes, megabytes, gigabytes and terabytes.
Key Concepts of this section:
Know the difference between storage devices and storage media.
Be able to name the different storage capacity units (from smallest to largest).

Storage Media (a quick introduction)
Key Words:
Storage device , Storage media, Internal, External, Magnetic, Optical, Solid-State
Storage media is the term given to the devices that are used to hold data.
Storage media is NOT the same thing as a storage device.
  • Storage media = the part that holds the data
  • Storage device = the machine that reads/writes data to and from the media

The CD is the 'media' (where data is held)
The CD Drive is the 'device' (reads data on media).
There are 2 types of computer storage -
Permanent and Temporary.
All 3 types of media are covered in more detail in the next 3 sections of this unit.

Storage media is 'permanent storage' and will hold data even when the computer is powered off.

Permanent storage devices:
Devices that hold data without power and are known as 'non-volatile'

Temporary storage devices:
Devices that lose data without power and are known as 'volatile'.

Storage media can either be:
  • Internal - inside the computer
  • External - plugged into the computer from outside (e.g. usb stick)
There are 3 different types of storage media and they all store data in different ways. These are summarised below:

Storage Media
1. Magnetic media
  • Holds data magnetically
  • Surface area of the media are magnetised so that they can hold 'bits' of data
  • The device that reads the media can also read the bits held on the surface area.
2. Optical media
  • Holds data by burning 'dots' onto the surface with a high powered laser
  • The device that reads the media can read the data by shining a lower powered laser over the dots .
3. Solid-state media
  • Holds data on devices that have no moving parts.


Storage Capacity
Key Words:
Bit, Byte, Kilobyte, Megabyte, Gigabyte, Terabyte

Storage capacity is the term given to the maximum amount of data that can be stored on the media.

Storage amounts are measured in 'bytes' and there are 8 bits in 1 byte.

Bits are short for 'binary digits'. This is the smallest unit of data that can be stored. Each 'bit' is represented as a binary number, either 1 or 0.

A single letter on a keyboard takes up 1 byte of storage (8 bits).

There are 8 bits (binary digits) in 1 byte of data.
(click to zoom)
There are 16 bits in 2 bytes of data.
(click to zoom)
Floppy disks can't store very much data
(about 1.44 MB).
CD's can hold about 800 MB of data.
Hard disk drives can store terabytes of data. This is the equivalent of many libraries full of books.

Computers read and process everything in the form of binary numbers. Each binary number takes up 1 bit of storage.

For example:
The letter C looks like 01000011 to a computer. There are 8 binary numbers.... so 'C' takes up 8 bits or 1 byte of storage.

Click here for a text to binary converter to see what other keyboard characters look like in binary.

Storage Capacity Units:
We refer to the storage capacities of different media in the following units:

Smallest unit of data (either a 1 or a 0)
1 byte = 8 bits
1 KB = 1024 bytes
1 MB = 1024 Kilobytes
1 GB = 1024 Megabytes
1 TB = 1024 Gigabytes

Storage media all have different storage capacities.

For example:
Hard disk drives have capacities in the terabytes.

Floppy disk drives can only hold 1.44MB of data.

Storage Capacity Examples:
The table below gives you some real-world examples of approximately how much data we could store on storage media with different capacities:

Storage Media Capacity
How much Data could be Stored
1 kilobyte
1 thousand characters (half a page of text)
1 megabyte
1 million characters (500 pages of text)
1 Gigabyte
1 billion characters (500,000 pages of text)
1 Terabyte 1 trillion characters (1,000,000 thick books)